Electrochem

2024

Jump to: 2023, 2022, 2021

14 pages, 4285 KiB

Open AccessArticle

Full Tailored Metal Content NCM Regeneration from Spent Lithium-Ion Battery Mixture Under Mild Condition

by Alpha Chi Him Tsang, Shaobo Ouyang, Yang Lv, Chi Chung Lee, Chi-Wing Tsang and Xiao-Ying Lu

Electrochem 2024, 5(4), 546-559; https://doi.org/10.3390/electrochem5040035 - 2 Dec 2024

Viewed by 400

Abstract

Mild conditioned, second-life ternary nickel–cobalt–manganese (NCM) black powder regeneration from spent lithium-ion batteries’ (LIBs) black powder mixture was demonstrated after mild conditioned p-toluenesulphuric acid (PTA)-assisted wet leaching. The NCM ratio was tailored to several combinations (333, 523, 532, and 622) by adding a [...] Read more.

Mild conditioned, second-life ternary nickel–cobalt–manganese (NCM) black powder regeneration from spent lithium-ion batteries’ (LIBs) black powder mixture was demonstrated after mild conditioned p-toluenesulphuric acid (PTA)-assisted wet leaching. The NCM ratio was tailored to several combinations (333, 523, 532, and 622) by adding a suitable amount of metal (Ni, Co, Mn)-sulphate salt to the leachate. Regenerated NCM was obtained by co-precipitation with sodium hydroxide pellets and ammonia pH buffering solution, followed by lithium (Li) sintering under ambient air and size sieving. The obtained regenerated NCM powder was used for the energy storage materials (ESM) in coin cell (Li half-cell, CR2032) evaluation. Systematic characterization of regenerated NCM showed that the NCM ratio was close to the target value as assigned in the tailored process, and regenerated 622 (R622) exhibited strong activity in CR2032 coin cell testing among all four ratios with a maximum discharge capacity of 196.6 mAh/g. Full article

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30 pages, 7900 KiB

Open AccessArticle

A Carbon-Particle-Supported Palladium-Based Cobalt Composite Electrocatalyst for Ethanol Oxidation Reaction (EOR)

by Keqiang Ding, Weijia Li, Mengjiao Li, Ying Bai, Xiaoxuan Liang and Hui Wang

Electrochem 2024, 5(4), 506-529; https://doi.org/10.3390/electrochem5040033 - 15 Nov 2024

Viewed by 444

Abstract

For the first time, carbon-particle-supported palladium-based cobalt composite electrocatalysts (abbreviated as Pd_xCo_y/CPs) were prepared using a calcination–hydrothermal process–hydrothermal process (denoted as CHH). The catalysts of Pd_xCo_y/CPs prepared using CoC₂O₄·2H₂O, [...] Read more.

For the first time, carbon-particle-supported palladium-based cobalt composite electrocatalysts (abbreviated as Pd_xCo_y/CPs) were prepared using a calcination–hydrothermal process–hydrothermal process (denoted as CHH). The catalysts of Pd_xCo_y/CPs prepared using CoC₂O₄·2H₂O, (CH₃COO)₂Co·4H₂O, and metallic cobalt were named catalyst c₁, c₂, and c₃, respectively. For comparison, the catalyst prepared in the absence of a Co source (denoted as Pd/CP) was identified as catalyst c₀. All fabricated catalysts were thoroughly characterized by XRD, EDS, XPS, and FTIR, indicating that PdO, metallic Pd, carbon particles, and a very small amount of cobalt oxide were the main components of all produced catalysts. As demonstrated by the traditional electrochemical techniques of CV and CA, the electrocatalytic performances of Pd_xCo_y/CP towards the ethanol oxidation reaction (EOR) were significantly superior to that of Pd/CP. In particular, c₁ showed an unexpected electrocatalytic activity for EOR; for instance, in the CV test, the peak f current density of EOR on catalyst c₁ was 129.3 mA cm⁻², being about 10.7 times larger than that measured on Pd/CP, and in the CA test, the polarized current density of EOR recorded for c₁ after 7200 s was still about 2.1 mA cm⁻², which was larger than that recorded for Pd/CP (0.6 mA cm⁻²). In the catalyst preparation process, except for the elements of C, O, Co, and Pd, no other elements were involved, which was thought to be the main contribution of this preliminary work, being very meaningful to the further exploration of Pd-based composite EOR catalysts. Full article

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15 pages, 5515 KiB

Open AccessArticle

Electrochemical Sensing of Hydrogen Peroxide Using Composite Bismuth Oxide/Bismuth Oxyselenide Nanostructures: Antagonistic Influence of Tungsten Doping

by Pooja D. Walimbe, Rajeev Kumar, Amit Kumar Shringi, Obed Keelson, Hazel Achieng Ouma and Fei Yan

Electrochem 2024, 5(4), 455-469; https://doi.org/10.3390/electrochem5040030 - 24 Oct 2024

Viewed by 726

Abstract

This study investigates the underlying mechanisms of hydrogen peroxide (H₂O₂) sensing using a composite material of bismuth oxide and bismuth oxyselenide (Bi₂O_xSe_y). The antagonistic effect of tungsten (W)-doping on the electrochemical behavior was also examined. Undoped, 2 [...] Read more.

This study investigates the underlying mechanisms of hydrogen peroxide (H₂O₂) sensing using a composite material of bismuth oxide and bismuth oxyselenide (Bi₂O_xSe_y). The antagonistic effect of tungsten (W)-doping on the electrochemical behavior was also examined. Undoped, 2 mol%, 4 mol%, and 6 mol% W-doped Bi₂O_xSe_y nanostructures were synthesized using a one-pot solution phase method involving selenium powder and hydrazine hydrate. W-doping induced a morphological transformation from nanosheets to spherical nanoparticles and amorphization of the bismuth oxyselenide phase. Electrochemical sensing measurements were conducted using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). H₂O₂ detection was achieved over a wide concentration range of 0.02 to 410 µM. In-depth CV analysis revealed the complex interplay of oxidation-reduction processes within the bismuth oxide and Bi₂O₂Se components of the composite material. W-doping exhibited an antagonistic effect, significantly reducing sensitivity. Among the studied samples, undoped Bi₂O_xSe_γ demonstrated a high sensitivity of 83 μA μM⁻¹ cm⁻² for the CV oxidation peak at 0 V, while 6 mol% W-Bi₂O_xSe_y became completely insensitive to H₂O₂. Interestingly, DPV analysis showed a reversal of sensitivity trends with 2 and 4 mol% W-doping. The applicability of these samples for real-world analysis, including rainwater and urine, was also demonstrated. Full article

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14 pages, 3075 KiB

Open AccessArticle

Pseudospherical Bismuth Oxychloride-Modified Carbon Paste Electrode for the Determination of Quinine in Beverages

by Tijana Mutić, Vesna Stanković, Miloš Ognjanović, Vladimir B. Nikolić, Guanyue Gao, Neso Sojic and Dalibor Stanković

Electrochem 2024, 5(4), 407-420; https://doi.org/10.3390/electrochem5040027 - 15 Oct 2024

Viewed by 742

Abstract

The extensive use of the alkaloid quinine (QN) in the cosmetic and food industries has induced major concerns relating to its impact on human health, considering its potential toxicity. Therefore, developing sensitive and selective electrochemical sensors is crucial for monitoring QN in environmental, [...] Read more.

The extensive use of the alkaloid quinine (QN) in the cosmetic and food industries has induced major concerns relating to its impact on human health, considering its potential toxicity. Therefore, developing sensitive and selective electrochemical sensors is crucial for monitoring QN in environmental, food, and pharmaceutical samples. To respond to this need, a surfactant-supported green synthesis approach, based on a straightforward, organic solvent-free hydrothermal method was employed to synthesize highly crystalline pseudospherical bismuth oxychloride (BiOCl) nanoparticles. This material was used for the enrichment of carbon paste electrodes and its further utilization for the detection and quantification of quinine. They have superior electrocatalytic performance, due to their size and morphology, and facilitate the interactions of the target with the electrode surface. Under optimal operating conditions, differential pulse voltammetry demonstrated a remarkable feature: a broad linear working range of 10 to 140 μM, a detection limit of 0.14 μM, and a high sensitivity of 1.995 μA μM⁻¹ cm⁻². The suggested method’s satisfactory sensitivity, along with its good stability, repeatability, and reproducibility, strongly point to a possible use for identifying quinine in real samples. Full article

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13 pages, 1732 KiB

Open AccessArticle

Low-Volume Electrochemical Sensor Platform for Direct Detection of Paraquat in Drinking Water

by Durgasha C. Poudyal, Manish Samson, Vikram Narayanan Dhamu, Sera Mohammed, Claudia N. Tanchez, Advaita Puri, Diya Baby, Sriram Muthukumar and Shalini Prasad

Electrochem 2024, 5(3), 341-353; https://doi.org/10.3390/electrochem5030022 - 22 Aug 2024

Viewed by 1103

Abstract

Direct testing of pesticide contaminants in drinking water is a challenge. Portable and sensitive sensor platforms are desirable to test water contaminants directly at farm and consumer levels. In this study, we have demonstrated the feasibility of an electrochemical sensor for the direct [...] Read more.

Direct testing of pesticide contaminants in drinking water is a challenge. Portable and sensitive sensor platforms are desirable to test water contaminants directly at farm and consumer levels. In this study, we have demonstrated the feasibility of an electrochemical sensor for the direct detection of paraquat (PQ) in drinking water samples. An immunoassay-based sensing platform was fabricated using PQ-specific antibody immobilized on the surface of the electrochemically reduced graphene oxide (rGO) modified screen-printed carbon electrode (rGO-SPCE). Using non-faradaic electrochemical impedance spectroscopy (EIS) as a detection tool, the sensor platform demonstrated a dynamic response for PQ concentration in drinking water ranging from 0.05 ng/mL to 72.9 ng/mL (0.19 to 243.8 nM), with a coefficient of determination (r²) of 0.997 and a limit of detection of 0.05 ng/mL (0.19 nM). Percentage recovery within ±20% error was obtained, and the sensor cross-reactivity test showed a selective response against glyphosate antigen. With the flexibility to use single-frequency EIS and low sample volume, the developed sensor demonstrated testing in water samples directly without any sample pre-processing. This low-volume electroanalytical sensor platforms can be translated into portable testing tools for the detection of various water contaminants. Full article

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11 pages, 5575 KiB

Open AccessArticle

Nanowire Electrode Structures Enhanced Direct Extracellular Electron Transport via Cell-Surface Multi-Heme Cytochromes in Desulfovibrio ferrophilus IS5

by Xiao Deng, Wipakorn Jevasuwan, Naoki Fukata and Akihiro Okamoto

Electrochem 2024, 5(3), 330-340; https://doi.org/10.3390/electrochem5030021 - 13 Aug 2024

Viewed by 1019

Abstract

Extracellular electron transfer (EET) by sulfate-reducing bacteria (SRB), such as Desulfovibrio ferrophilus IS5, enables bacterial interactions with minerals, which are vital for biogeochemical cycling and environmental chemistry. Here, we explore the direct EET mechanisms through outer-membrane cytochromes (OMCs) using IS5 as a model [...] Read more.

Extracellular electron transfer (EET) by sulfate-reducing bacteria (SRB), such as Desulfovibrio ferrophilus IS5, enables bacterial interactions with minerals, which are vital for biogeochemical cycling and environmental chemistry. Here, we explore the direct EET mechanisms through outer-membrane cytochromes (OMCs) using IS5 as a model SRB. We employed nanostructured electrodes arrayed with 0, 50, 200, and 500 nm long nanowires (NWs) coated with indium–tin–doped oxide to examine the impact of electrode morphology on the direct EET efficacy. Compared to flat electrodes, NW electrodes significantly enhanced current production in IS5 with OMCs. However, this enhancement was diminished when OMC expression was reduced. Differential pulse voltammetry revealed that NW electrodes specifically augmented redox peaks associated with OMCs without affecting those related to redox mediators, suggesting that NWs foster direct EET through OMCs. Scanning electron microscopy observations following electrochemical analyses revealed a novel vertical cell attachment and aggregation on NW electrodes, contrasting with the horizontal monolayer cell attachment on flat electrodes. This study presents the first evidence of the critical role of electrode nanoscale topography in modulating SRB cell orientation and aggregation behavior. The findings underscore the significant influence of electrode morphology on the direct EET kinetics, highlighting the potential impact of mineral morphology on mineral reduction and biogeochemical processes. Full article

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16 pages, 10346 KiB

Open AccessArticle

Hierarchical Two-Dimensional Layered Nickel Disulfide (NiS₂)@PEDOT:PSS Nanocomposites as Battery-Type Electrodes for Battery-Type Supercapacitors with High Energy Density

by Susmi Anna Thomas, Jayesh Cherusseri and Deepthi N. Rajendran

Electrochem 2024, 5(3), 298-313; https://doi.org/10.3390/electrochem5030019 - 17 Jul 2024

Cited by 3 | Viewed by 1048

Abstract

Battery-type hybrid supercapacitors (HSCs) (otherwise known as supercapatteries) are novel electrochemical energy storage devices bridge the gap between rechargeable batteries and traditional SCs. Herein, we report the synthesis of layered two-dimensional (2D) nickel disulfide (NiS₂) nanosheets (NSNs) modified with poly(3,4-ethylenedioxythiophene:polystyrene sulfonate [...] Read more.

Battery-type hybrid supercapacitors (HSCs) (otherwise known as supercapatteries) are novel electrochemical energy storage devices bridge the gap between rechargeable batteries and traditional SCs. Herein, we report the synthesis of layered two-dimensional (2D) nickel disulfide (NiS₂) nanosheets (NSNs) modified with poly(3,4-ethylenedioxythiophene:polystyrene sulfonate (PEDOT:PSS) and their successful implementation in battery-type SCs. Initially, a layered 2D NSN is synthesized via a microwave-assisted hydrothermal method and further used as a template to coat PEDOT:PSS in order to prepare NiS₂@PEDOT:PSS nanocomposite electrodes by a facile drop-casting method. This is the first-time report on the synthesis of a hierarchical NiS₂@PEDOT:PSS nanocomposite electrode for battery-type HSC applications. An asymmetric battery-type HSC fabricated with NSN@PEDOT:PSS nanocomposite as positrode and activated carbon as negatrode delivers a maximum energy density of 52.1 Wh/kg at a current density of 1.6 A/g with a corresponding power density of 2500 W/kg. Full article

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13 pages, 1108 KiB

Open AccessArticle

Reduced Graphene Oxide Decorated Titanium Nitride Nanorod Array Electrodes for Electrochemical Applications

by Md Shafiul Islam, Alan Branigan, Dexian Ye and Maryanne M. Collinson

Electrochem 2024, 5(3), 274-286; https://doi.org/10.3390/electrochem5030017 - 3 Jul 2024

Cited by 1 | Viewed by 1601

Abstract

This work describes the fabrication and characterization of a new high surface area nanocomposite electrode containing reduced graphene oxide (rGO) and titanium nitride (TiN) for electrochemical applications. This approach involves electrochemically depositing rGO on a high surface area TiN nanorod array electrode to [...] Read more.

This work describes the fabrication and characterization of a new high surface area nanocomposite electrode containing reduced graphene oxide (rGO) and titanium nitride (TiN) for electrochemical applications. This approach involves electrochemically depositing rGO on a high surface area TiN nanorod array electrode to form a new nanocomposite electrode. The TiN nanorod array was first formed by the glancing angle deposition technique in a DC (Direct Current) sputtering system. GO flakes of ~1.5 μm in diameter, as confirmed by Dynamic Light Scattering (DLS), were electrodeposited on the nanostructured TiN electrode via the application of a fixed potential for one hour. The surface morphology of the as-prepared rGO/TiN electrode was evaluated by scanning electron microscopy (SEM) and the presence of rGO on TiN was confirmed by Raman Microscopy. The CV shows an increase in the capacitive current at rGO/TiN as compared to TiN. The rGO decorated TiN electrode was then used for analyzing the electrocatalytic oxidation of ascorbic acid and dopamine, and the reduction of nitrate by CV and linear sweep voltammetry (LSV), respectively. CV or LSV show that the electrochemical kinetics of these three analytes are significantly faster on rGO/TiN than TiN itself. Overall, the rGO/TiN electrode showed better electrochemical behavior for biomolecules like ascorbic acid and dopamine as well as another target analyte, nitrate ions, compared to TiN by itself. Full article

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15 pages, 2501 KiB

Open AccessArticle

Detection of Ovarian Cancer Biomarker Lysophosphatidic Acid Using a Label-Free Electrochemical Biosensor

by Nataliia Ivanova, Soha Ahmadi, Edmund Chan, Léa Fournier, Sandro Spagnolo and Michael Thompson

Electrochem 2024, 5(2), 243-257; https://doi.org/10.3390/electrochem5020015 - 18 Jun 2024

Viewed by 1365

Abstract

Electrochemical biosensors are valued for their sensitivity and selectivity in detecting biological molecules. Having the advantage of generating signals that can be directly or indirectly proportional to the concentration of the target analyte, these biosensors can achieve specificity by utilizing a specific biorecognition [...] Read more.

Electrochemical biosensors are valued for their sensitivity and selectivity in detecting biological molecules. Having the advantage of generating signals that can be directly or indirectly proportional to the concentration of the target analyte, these biosensors can achieve specificity by utilizing a specific biorecognition surface designed to recognize the target molecule. Electrochemical biosensors have garnered substantial attention, as they can be used to fabricate compact, cost-effective devices, making them promising candidates for point-of-care testing (POCT) devices. This study introduces a label-free electrochemical biosensor employing a gold screen-printed electrode (SPE) to detect lysophosphatidic acid (LPA), a potential early ovarian cancer biomarker. We employed the gelsolin–actin system, previously introduced by our group, in combination with fluorescence spectrometry, as a biorecognition element to detect LPA. By immobilizing a gelsolin–actin complex on an SPE, we were able to quantify changes in current intensity using cyclic voltammetry and differential pulse voltammetry, which was directly proportional to the LPA concentration in the solution. Our results demonstrate the high sensitivity of the developed biosensor for detecting LPA in goat serum, with a limit of detection (LOD) and a limit of quantification (LOQ) of 0.9 µM and 2.76 µM, respectively, highlighting its potential as a promising tool for early-stage diagnosis of ovarian cancer. Full article

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20 pages, 12050 KiB

Open AccessArticle

High C-Rate Performant Electrospun LiFePO₄/Carbon Nanofiber Self-Standing Cathodes for Lithium-Ion Batteries

by Debora Maria Conti, Claudia Urru, Giovanna Bruni, Pietro Galinetto, Benedetta Albini, Vittorio Berbenni and Doretta Capsoni

Electrochem 2024, 5(2), 223-242; https://doi.org/10.3390/electrochem5020014 - 5 Jun 2024

Cited by 1 | Viewed by 1626

Abstract

In the present study, LiFePO₄/CNF self-standing cathodes for LIBs are synthesized by electrospinning. A lower active material amount (12.3 and 34.5 wt%) is used, compared to the conventional tape-casted cathodes (70–85 wt%). The characterization techniques (XRPD, SEM, TEM, EDS, Raman spectroscopy, [...] Read more.

In the present study, LiFePO₄/CNF self-standing cathodes for LIBs are synthesized by electrospinning. A lower active material amount (12.3 and 34.5 wt%) is used, compared to the conventional tape-casted cathodes (70–85 wt%). The characterization techniques (XRPD, SEM, TEM, EDS, Raman spectroscopy, and thermogravimetry) confirm that the olivine-type structure of LiFePO₄ is maintained in the binder-free electrodes, and the active material is homogeneously dispersed into and within the carbon nanofibers. The electrochemical investigation demonstrates that higher Li⁺ diffusion coefficients (1.36 × 10⁻¹¹ cm²/s) and improved reversibility are reached for free-standing electrodes, compared to the LiFePO₄ tape-casted cathode (80 wt% of active material) appositely prepared for comparison. The 34.5 wt% LiFePO₄ self-standing cathode displays a lower capacity fading, good reversibility and stability, enhanced capacity values at C-rates higher than 5C, and a good lifespan when cycled 1000 cycles at 1C and further cycled up to 20C, compared to the tape-casted counterpart. Notably, the improved electrochemical performances are obtained by only the 34.5 wt% of active material. The results evidence the relevant role of the CNF matrix suitable to host LiFePO₄, to promote electrolyte permeation and contact with the active material, and to increase the electronic conductivity. Full article

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35 pages, 3837 KiB

Open AccessReview

Ion-Selective Electrodes in the Food Industry: Development Trends in the Potentiometric Determination of Ionic Pollutants

by Antonio Ruiz-Gonzalez

Electrochem 2024, 5(2), 178-212; https://doi.org/10.3390/electrochem5020012 - 21 May 2024

Viewed by 2116

Abstract

Food quality assessment is becoming a global priority due to population growth and the rise of ionic pollutants derived from anthropogenic sources. However, the current methods used to quantify toxic ions are expensive and their operation is complex. Consequently, there is a need [...] Read more.

Food quality assessment is becoming a global priority due to population growth and the rise of ionic pollutants derived from anthropogenic sources. However, the current methods used to quantify toxic ions are expensive and their operation is complex. Consequently, there is a need for affordable and accessible methods for the accurate determination of ion concentrations in food. Electrochemical sensors based on potentiometry represent a promising approach in this field, with the potential to overcome limitations of the currently available systems. This review summarizes the current advances in the electrochemical quantification of heavy metals and toxic anions in the food industry using potentiometric sensors. The healthcare impact of common heavy metal contaminants (Cd²⁺, Hg²⁺, Pb²⁺, As³⁺) and anions (ClO₄⁻, F⁻, HPO₄⁻, SO₄²⁻, NO₃⁻, NO₂⁻) is discussed, alongside current regulations, and gold standard methods for analysis. Sensor performances are compared to current benchmarks in terms of selectivity and the limit of detection. Given the complexity of food samples, the percentage recovery values (%) and the methodologies employed for ion extraction are also described. Finally, a summary of the challenges and future directions of the field is provided. An overview of technologies that can overcome the limitations of current electrochemical sensors is shown, including new extraction methods for ions in food. Full article

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13 pages, 2708 KiB

Open AccessArticle

High-Rate Performance of a Designed Si Nanoparticle–Graphite Nanosheet Composite as the Anode for Lithium-Ion Batteries

by Vahide Ghanooni Ahmadabadi, Md Mokhlesur Rahman and Ying Chen

Electrochem 2024, 5(2), 133-145; https://doi.org/10.3390/electrochem5020009 - 9 Apr 2024

Viewed by 1868

Abstract

A silicon nanoparticle–graphite nanosheet composite was prepared via a facile ball milling process for use as the anode for high-rate lithium-ion batteries. The size effect of Si nanoparticles on the structure and on the lithium-ion battery performance of the composite is evaluated. SEM [...] Read more.

A silicon nanoparticle–graphite nanosheet composite was prepared via a facile ball milling process for use as the anode for high-rate lithium-ion batteries. The size effect of Si nanoparticles on the structure and on the lithium-ion battery performance of the composite is evaluated. SEM and TEM analyses show a structural alteration of the composites from Si nanoparticle-surrounded graphite nanosheets to Si nanoparticle-embedded graphite nanosheets by decreasing the size of Si nanoparticles from 250 nm to 40 nm. The composites with finer Si nanoparticles provide an effective nanostructure containing encapsulated Si and free space. This structure facilitates the indirect exposure of Si to electrolyte and Si expansion during cycling, which leads to a stable solid–electrolyte interphase and elevated conductivity. An enhanced rate capability was obtained for the 40 nm Si nanoparticle–graphite nanosheet composite, delivering a specific capacity of 276 mAh g⁻¹ at a current density of 1 C after 1000 cycles and a rate capacity of 205 mAh g⁻¹ at 8 C. Full article

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14 pages, 5415 KiB

Open AccessArticle

The Electrocatalytic Oxygen Evolution Reaction Activity of Rationally Designed NiFe-Based Glycerates

by Vivek Kumar Singh, Bibhudatta Malik, Rajashree Konar, Efrat Shawat Avraham and Gilbert Daniel Nessim

Electrochem 2024, 5(1), 70-83; https://doi.org/10.3390/electrochem5010005 - 4 Feb 2024

Viewed by 1897

Abstract

The electrocatalytic oxygen evolution reaction (OER) is an arduous step in water splitting due to its slow reaction rate and large overpotential. Herein, we synthesized glycerate-anion-intercalated nickel–iron glycerates (NiFeGs) using a one-step solvothermal reaction. We designed various NiFeGs by tuning the molar ratio [...] Read more.

The electrocatalytic oxygen evolution reaction (OER) is an arduous step in water splitting due to its slow reaction rate and large overpotential. Herein, we synthesized glycerate-anion-intercalated nickel–iron glycerates (NiFeGs) using a one-step solvothermal reaction. We designed various NiFeGs by tuning the molar ratio between Ni and Fe to obtain Ni₄Fe₁G, Ni₃Fe₁G, Ni₃Fe₂G, and Ni₁Fe₁G, which we tested for their OER performance. We initially analyzed the catalytic performance of powder samples immobilized on glassy carbon electrodes using a binder. Ni₃Fe₂G outperformed the other NiFeG compositions, including NiFe layered double hydroxide (LDH). It exhibited an overpotential of 320 mV at a current density of 10 mA cm^–2 in an electrolytic solution of pH 14. We then synthesized carbon paper (CP)-modified Ni₃Fe₂G as a self-supported electrode (Ni₃Fe₂G/CP), and it exhibited a high current density (100 mA cm⁻²) at a low overpotential of 300 mV. The redox peak analysis for the NiFeGs revealed that the initial step of the OER is the formation of γ-NiOOH, which was further confirmed by a post-Raman analysis. We extensively analyzed the catalyst’s stability and lifetime, the nature of the active sites, and the role of the Fe content to enhance the OER performance. This work may provide the motivation to study metal-alkoxide-based efficient OER electrocatalysts that can be used for alkaline water electrolyzer applications. Full article

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2023

Jump to: 2024, 2022, 2021

28 pages, 12368 KiB

Open AccessArticle

Identification of the Safe Variation Limits for the Optimization of the Measurements in Low-Cost Electrochemical Air Quality Sensors

by Ioannis Christakis, Elena Sarri, Odysseas Tsakiridis and Ilias Stavrakas

Electrochem 2024, 5(1), 1-28; https://doi.org/10.3390/electrochem5010001 - 21 Dec 2023

Cited by 5 | Viewed by 1686

Abstract

Nowadays, the study of air quality has become an increasingly prominent field of research, particularly in large urban centers, given its significant impact on human health. In many countries, government departments and research centers use official high-cost scientific instruments to monitor air quality [...] Read more.

Nowadays, the study of air quality has become an increasingly prominent field of research, particularly in large urban centers, given its significant impact on human health. In many countries, government departments and research centers use official high-cost scientific instruments to monitor air quality in their regions. Meanwhile, concerned citizens interested in studying the air quality of their local areas often employ low-cost air quality sensors for monitoring purposes. The optimization and evaluation of low-cost sensors have been a field of research by many research groups. This paper presents an extensive study to identify the safe percentage change limits that low-cost electrochemical air quality sensors can have, in order to optimize their measurements. For this work, three low-cost air quality monitoring stations were used, which include an electrochemical sensor for nitrogen dioxide (NO₂) (Alphasense NO2-B43F) and an electrochemical sensor for ozone (O₃) (Alphasense OX-B431). The aim of this work is to explore the variance of the aforementioned sensors and how this variability can be used to optimize the measurements of low-cost electrochemical sensors, closer to real ones. The analysis is conducted by employing diagrams, boxplot and violin curves of the groups of sensors used, with satisfactory results. Full article

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15 pages, 2250 KiB

Open AccessReview

Relevant Aspects in the Development of Electrochemical Aptasensors for the Determination of Antibiotics—A Review

by Daniela Nunes da Silva and Arnaldo César Pereira

Electrochem 2023, 4(4), 553-567; https://doi.org/10.3390/electrochem4040035 - 12 Dec 2023

Cited by 1 | Viewed by 1838

Abstract

Aptamers are three-dimensional structures of DNA or RNA that present high affinity and selectivity to specific targets, obtained through in vitro screening. Aptamers are used as biological recognizers in electrochemical biosensors, the so-called aptasensors, providing greater specificity in recognizing the most diverse analytes. [...] Read more.

Aptamers are three-dimensional structures of DNA or RNA that present high affinity and selectivity to specific targets, obtained through in vitro screening. Aptamers are used as biological recognizers in electrochemical biosensors, the so-called aptasensors, providing greater specificity in recognizing the most diverse analytes. Electrochemical aptasensors have extremely relevant characteristics, such as high sensitivity, low cost compared to other biorecognizers such as antibodies, and excellent compatibility, being considered one of the most promising alternative methods in several areas, such as biomedical diagnosis and monitoring environmental contaminants. In this sense, the present work reviews the relevant aspects of methodologies based on electrochemical aptasensors and their applications in determining antibiotics, seeking to foster innovation in electrochemical biosensors. Full article

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12 pages, 2243 KiB

Open AccessArticle

Graphene-Oxide-Coated CoP₂@C Anode Enables High Capacity of Lithium-Ion Batteries

by Wei Zhang, Hangxuan Xie, Zirui Dou, Zhentao Hao, Qianhui Huang, Ziqi Guo, Chao Wang, Kanghua Miao and Xiongwu Kang

Electrochem 2023, 4(4), 473-484; https://doi.org/10.3390/electrochem4040031 - 26 Oct 2023

Cited by 2 | Viewed by 1946

Abstract

Cobalt diphosphides (CoP₂) show a high theoretical capacity and hold great promise as anode materials for lithium-ion batteries (LIBs). However, the large variation in the volume and structure of CoP₂ caused during lithium-ion insertion and extraction results in electrode fragmentation [...] Read more.

Cobalt diphosphides (CoP₂) show a high theoretical capacity and hold great promise as anode materials for lithium-ion batteries (LIBs). However, the large variation in the volume and structure of CoP₂ caused during lithium-ion insertion and extraction results in electrode fragmentation and a compromised solid electrolyte interface, ultimately leading to poor cycling performance. Herein, a composite of CoP₂ nanoparticles encapsulated in carbon matrix has been successfully synthesized by carbonization of Co-MOF-based zeolitic imidazolate frameworks (ZIF-67) and sequential phosphorization and further wrapped in graphene oxide (CoP₂@C@GO). The formation of CoP₂ was confirmed by X-ray diffraction, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The morphology of CoP₂@C with and without GO wrapping was examined by scanning electron microscopy and transmission electron spectroscopy. It was demonstrated that the decoration of GO significantly reduces the polarization of CoP₂@C electrodes, enhancing their charge capacity and cycling stability as an anode material for LIBs. After 200 cycles, they deliver a capacity of 450 mAh·g⁻¹. Full article

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13 pages, 2273 KiB

Open AccessReview

Design and Development of Food Waste Inspired Electrochemical Platform for Various Applications

by Mansi Gandhi

Electrochem 2023, 4(3), 411-423; https://doi.org/10.3390/electrochem4030026 - 14 Aug 2023

Cited by 2 | Viewed by 2682

Abstract

Plants have a remarkable position among renewable materials because of their abundance, and nearly thousands of tons are consumed worldwide every day. Most unexploited plants and agricultural waste can be a real potential resource system. With increasing environmental awareness and the growing importance [...] Read more.

Plants have a remarkable position among renewable materials because of their abundance, and nearly thousands of tons are consumed worldwide every day. Most unexploited plants and agricultural waste can be a real potential resource system. With increasing environmental awareness and the growing importance of friendly agricultural waste, crops and fruit waste can be used for efficient conversion into bio-fertilizers, biocarbons, bio-polymers, biosensors and bio-fibers. Global challenges based on limited natural resources and fossil energy reserves simulated keen interest in the development of various electrochemical systems inspired by food and plant scraps, which aid in curbing pollution. The successful adoption of a renewable energy roadmap is dependent on the availability of a cheaper means of storage. In order to cut down the cost of storage units, an improvement on energy storage devices having better stability, power, and energy density with low post-maintenance cost is the vital key. Although food and plant scraps have a huge need for energy storage, it has been extended to various sensing platform fabrications, which are eco-friendly and comparable to organic molecule-based sensors. Current research proclivity has witnessed a huge surge in the development of phyto-chemical-based sensors. The state-of-the-art progresses on the subsequent use of plant-waste systems as nano-engineered electrochemical platforms for numerous environmental science and renewable energy applications. Moreover, the relevant rationale behind the use of waste in a well-developed, sustainable future device is also presented in this review. Full article

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15 pages, 3517 KiB

Open AccessArticle

Electrochemical Properties of Sputtered Ruthenium Oxide Neural Stimulation and Recording Electrodes

by Bitan Chakraborty

Electrochem 2023, 4(3), 350-364; https://doi.org/10.3390/electrochem4030023 - 24 Jul 2023

Viewed by 1979

Abstract

A chronically stable electrode material with a low impedance for recording neural activity, and a high charge-injection capacity for functional electro-stimulation is desirable for the fabrication of implantable microelectrode arrays that aim to restore impaired or lost neurological functions in humans. For this [...] Read more.

A chronically stable electrode material with a low impedance for recording neural activity, and a high charge-injection capacity for functional electro-stimulation is desirable for the fabrication of implantable microelectrode arrays that aim to restore impaired or lost neurological functions in humans. For this purpose, we have investigated the electrochemical properties of sputtered ruthenium oxide (RuOx) electrode coatings deposited on planar microelectrode arrays, using an inorganic model of interstitial fluid (model-ISF) at 37 °C as the electrolyte. Through a combination of cyclic voltammetry (CV) and an electrochemical impedance spectroscopy (EIS) modelling study, we have established the contribution of the faradaic reaction as the major charge-injection contributor within the safe neural stimulation potential window of ±0.6 V vs. Ag|AgCl. We have also established the reversibility of the charge-injection process for sputtered RuOx film, by applying constant charge-per-phase current stimulations at different pulse widths, and by comparing the magnitudes of the leading and trailing access voltages during voltage transient measurements. Finally, the impedance of the sputtered RuOx film was found to be reasonably comparable in both its oxidized and reduced states, although the electronic contribution from the capacitive double-layer was found to be slightly higher for the completely oxidized film around 0.6 V than for its reduced counterpart around −0.6 V. Full article

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9 pages, 2957 KiB

Open AccessCommunication

Electrochemical Oxidation Profile of Anthocyanin Keracyanin on Glassy and Screen-Printed Carbon Electrodes

by Emad F. Newair, Aboelhasan G. Shehata and Menna Essam

Electrochem 2023, 4(2), 273-281; https://doi.org/10.3390/electrochem4020018 - 6 May 2023

Cited by 3 | Viewed by 2908

Abstract

A study of keracyanin chloride (KC) electrochemical behavior in an aqueous buffer solution using screen-printed carbon electrodes (SPCEs) and glassy carbon electrodes (GCEs) was performed. Cyclic voltammetry (CV) and square-wave voltammetry (SWV) were used to analyze the electrochemical response of KC under studied [...] Read more.

A study of keracyanin chloride (KC) electrochemical behavior in an aqueous buffer solution using screen-printed carbon electrodes (SPCEs) and glassy carbon electrodes (GCEs) was performed. Cyclic voltammetry (CV) and square-wave voltammetry (SWV) were used to analyze the electrochemical response of KC under studied conditions. A clear redox wave was observed for KC, primarily due to the oxidation of the catechol 3′,4′-dihydroxyl group of its ring B, with a minor redox wave from oxidation of the hydroxyl groups in ring A. Compared to GCEs, using modified SPCEs resulted in two-fold amplification in the electrochemical oxidation signal of KC. Using SPCEs as a working electrode could provide high sensitivity in the quantification of KC and the ability to gauge KC quantification to significantly lower detection limits. Full article

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27 pages, 3974 KiB

Open AccessReview

Recent Progression and Opportunities of Polysaccharide Assisted Bio-Electrolyte Membranes for Rechargeable Charge Storage and Conversion Devices

by Perumal Pandurangan

Electrochem 2023, 4(2), 212-238; https://doi.org/10.3390/electrochem4020015 - 10 Apr 2023

Cited by 2 | Viewed by 3006

Abstract

Polysaccharide-based natural polymer electrolyte membranes have had tremendous consideration for the various energy storage operations including wearable electronic and hybrid vehicle industries, due to their unique and predominant qualities. Furthermore, they have fascinating oxygen functionality results of a higher flexible nature and help [...] Read more.

Polysaccharide-based natural polymer electrolyte membranes have had tremendous consideration for the various energy storage operations including wearable electronic and hybrid vehicle industries, due to their unique and predominant qualities. Furthermore, they have fascinating oxygen functionality results of a higher flexible nature and help to form easier coordination of metal ions thus improving the conducting profiles of polymer electrolytes. Mixed operations of the various alkali and alkaline metal–salt-incorporated biopolymer electrolytes based on different polysaccharide materials and their charge transportation mechanisms are detailly explained in the review. Furthermore, recent developments in polysaccharide electrolyte separators and their important electrochemical findings are discussed and highlighted. Notably, the characteristics and ion-conducting mechanisms of different biopolymer electrolytes are reviewed in depth here. Finally, the overall conclusion and mandatory conditions that are required to implement biopolymer electrolytes as a potential candidate for the next generation of clean/green flexible bio-energy devices with enhanced safety; several future perspectives are also discussed and suggested. Full article

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31 pages, 5994 KiB

Open AccessArticle

Trends and Opportunities in Enzyme Biosensors Coupled to Metal-Organic Frameworks (MOFs): An Advanced Bibliometric Analysis

by Misael Bessa Sales, José Gadelha Lima Neto, Ana Kátia De Sousa Braz, Paulo Gonçalves De Sousa Junior, Rafael Leandro Fernandes Melo, Roberta Bussons Rodrigues Valério, Juliana de França Serpa, Ana Michele Da Silva Lima, Rita Karolinny Chaves De Lima, Artemis Pessoa Guimarães, Maria Cristiane Martins de Souza, Ada Amélia Sanders Lopes, Maria Alexsandra de Sousa Rios, Leonardo Farias Serafim and José Cleiton Sousa dos Santos

Electrochem 2023, 4(2), 181-211; https://doi.org/10.3390/electrochem4020014 - 7 Apr 2023

Cited by 19 | Viewed by 2986

Abstract

The unique properties of metal-organic frameworks (MOFs) such as their large surface area and high porosity have attracted considerable attention in recent decades. The MOFs are a promising class of materials for developing highly efficient biosensors due to these same properties. This bibliometric [...] Read more.

The unique properties of metal-organic frameworks (MOFs) such as their large surface area and high porosity have attracted considerable attention in recent decades. The MOFs are a promising class of materials for developing highly efficient biosensors due to these same properties. This bibliometric analysis focused on the use of MOFs as enzyme-coupled materials in biosensor construction and aimed to provide a comprehensive overview of the research field by analyzing a collected database. The analysis included identifying the countries that have published the most, the most prominent applications, and trends for future directions in the field. The study used three databases with different numbers of documents, differentiated by research areas, with refinements made to the search as needed. The results suggest that MOF-derived biosensors are a growing field, with the Republic of China emerging as a significant contributor to research in this area. The study also used computational processing of trend analysis and geocoding to reveal these findings. Full article

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25 pages, 6787 KiB

Open AccessReview

Review on Electrode Degradation at Fast Charging of Li-Ion and Li Metal Batteries from a Kinetic Perspective

by Jinghui Miao

Electrochem 2023, 4(2), 156-180; https://doi.org/10.3390/electrochem4020013 - 23 Mar 2023

Cited by 5 | Viewed by 5330

Abstract

With the surge of electric vehicles, fast charging has become one of the major challenges for the development of Li-ion and Li metal batteries. The degradation of battery electrodes at fast charging has been identified as among the gating factors. While there have [...] Read more.

With the surge of electric vehicles, fast charging has become one of the major challenges for the development of Li-ion and Li metal batteries. The degradation of battery electrodes at fast charging has been identified as among the gating factors. While there have been extensive studies on anode and cathode degradation modes, not sufficient efforts have been made to dive deep into the kinetics of battery charging and its influence on electrode degradation, especially during fast charging. This review presents a comprehensive yet concentrated perspective into such issues. By tracing back to the kinetic origins of battery charging, it is revealed that the intrinsic properties of electrode active materials and the microstructures of electrode are of great importance in determining electrode kinetics. Most of the electrode degradation modes are closely related to the high overpotentials and the spatial inhomogeneity in Li concentration and pertinent characteristics, which are results of the sluggish electrode kinetics during fast charging. Approaches to mitigate electrode degradation are summarized from the aspect of improving electrode kinetics and circumventing detrimental side reactions. Full article

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10 pages, 6797 KiB

Open AccessArticle

Impact of Ni Content on the Electrochemical Performance of the Co-Free, Li and Mn-Rich Layered Cathode Materials

by Gongshin Qi, Jiazhi Hu, Michael Balogh, Lei Wang, Devendrasinh Darbar and Wei Li

Electrochem 2023, 4(1), 21-30; https://doi.org/10.3390/electrochem4010002 - 12 Jan 2023

Cited by 4 | Viewed by 3052

Abstract

Li and Mn-rich layered cathode (LLC) materials show great potential as the next generation cathode materials because of their high, practical and achievable specific capacity of ~250 mAh/g, thermal stability and lower raw material cost. However, LLC materials suffer from degradation of specific [...] Read more.

Li and Mn-rich layered cathode (LLC) materials show great potential as the next generation cathode materials because of their high, practical and achievable specific capacity of ~250 mAh/g, thermal stability and lower raw material cost. However, LLC materials suffer from degradation of specific capacity, voltage fading due to phase transformation upon cycling and transition-metal dissolution, which presents a significant barrier for commercialization. Here, we report the effects of Ni content on the electrochemical performance, structural and thermal stability of a series of Co-free, LLC materials (Li_1.2Ni_xMn_0.8-xO₂, x = 0.12, 0.18, 0.24, 0.30 and 0.36) synthesized via a sol-gel method. Our study shows that the structure of the material as well as the electrochemical and thermal stability properties of the LLC materials are strongly dependent on the Ni or Mn content. An increase in the Ni to Mn ratio results in an increase in the average discharge voltage and capacity, as well as improved structural stability but decreased thermal stability. Full article

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2022

Jump to: 2024, 2023, 2021

11 pages, 3120 KiB

Open AccessArticle

Development of a Chemically Modified Electrode with Magnetic Molecularly Imprinted Polymer (MagMIP) for 17-β-Estradiol Determination in Water Samples

by Daniela Nunes da Silva and Arnaldo César Pereira

Electrochem 2022, 3(4), 809-819; https://doi.org/10.3390/electrochem3040053 - 2 Dec 2022

Cited by 2 | Viewed by 2102

Abstract

The present work consisted of the development of an electrode based on carbon paste modified with magnetic molecularly imprinted polymer (CPE-MagMIP) for 17-β-estradiol (E2) detection. The incorporation of magnetic material (MagMIP) improved sensor performance, an increase of over 317%. The proposed method resulted [...] Read more.

The present work consisted of the development of an electrode based on carbon paste modified with magnetic molecularly imprinted polymer (CPE-MagMIP) for 17-β-estradiol (E2) detection. The incorporation of magnetic material (MagMIP) improved sensor performance, an increase of over 317%. The proposed method resulted in a linear response range from 0.5 to 14.0 μM, and the detection limit (LOD) and quantification limit (LOQ) were equal to 0.13 and 0.44 μM, respectively. Under optimized conditions, the developed sensor obtained satisfactory parameters in E2 determination in water samples, demonstrating selectivity, accuracy, and precision, making it a promising method for monitoring E2 in environmental samples. Full article

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20 pages, 3005 KiB

Open AccessReview

Electric Double Layer: The Good, the Bad, and the Beauty

by André H. B. Dourado

Electrochem 2022, 3(4), 789-808; https://doi.org/10.3390/electrochem3040052 - 2 Dec 2022

Cited by 18 | Viewed by 11331

Abstract

The electric double layer (EDL) is the most important region for electrochemical and heterogeneous catalysis. Because of it, its modeling and investigation are something that can be found in the literature for a long time. However, nowadays, it is still a hot topic [...] Read more.

The electric double layer (EDL) is the most important region for electrochemical and heterogeneous catalysis. Because of it, its modeling and investigation are something that can be found in the literature for a long time. However, nowadays, it is still a hot topic of investigation, mainly because of the improvement in simulation and experimental techniques. The present review aims to present the classical models for the EDL, as well as presenting how this region affects electrochemical data in everyday experimentation, how to obtain and interpret information about EDL, and, finally, how to obtain some molecular point of view insights on it. Full article

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14 pages, 1453 KiB

Open AccessArticle

Application of Phanerochaete chrysopsorium-Based Carbon Paste Electrode as an Electrochemical Sensor for Voltammetric Detection of Hg (II) in Chlor-Alkali Industrial Effluent

by Maria Zaib, Umar Farooq and Muhammad Makshoof Athar

Electrochem 2022, 3(4), 746-759; https://doi.org/10.3390/electrochem3040049 - 7 Nov 2022

Cited by 1 | Viewed by 1887

Abstract

In this study, an electrochemical sensor for the monitoring of Hg (II) at trace levels by using differential pulse anodic stripping voltammetry has been reported. Basically the electrochemical sensor is a Phanerochaete chrysosporium-based carbon paste electrode. Here, Phanerochaete chrysosporium has played a [...] Read more.

In this study, an electrochemical sensor for the monitoring of Hg (II) at trace levels by using differential pulse anodic stripping voltammetry has been reported. Basically the electrochemical sensor is a Phanerochaete chrysosporium-based carbon paste electrode. Here, Phanerochaete chrysosporium has played a new vital role in electrochemical detection of heavy metal apart from its known contribution in their removal. Optimal voltammetric response was observed at −0.7 V deposition potential l, 5% biomass concentration ratio (w/w), and neutral pH conditions with 12 min as the accumulation time. Selectivity was evaluated in the presence of different interfering cations. Linear range was observed for 5–50 µgL⁻¹ of metal concentration with a detection limit of 4.4 µgL⁻¹. The equivalence of new and reference analytical methods was statistically assessed in mercury samples collected from chlor-alkali industrial effluent by correlation of results (Pearson’s product-moment correlation), weighted Deming regression analysis, paired comparison test, relative standard deviation (RSD), median relative error (MRE), root mean square error (RMSE), and predicted residual sum of square (PRESS). This work presented a simple, efficient, and promising analytical tool in trace level detection of Hg (II), as compared to previously reported carbon paste electrodes based on biological material. Full article

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18 pages, 23949 KiB

Open AccessArticle

Validation of Voltammetric Methods for Online Analysis of Platinum Dissolution in a Hydrogen PEM Fuel Cell Stack

by Lena Birkner and Maik Eichelbaum

Electrochem 2022, 3(4), 728-745; https://doi.org/10.3390/electrochem3040048 - 7 Nov 2022

Cited by 1 | Viewed by 2976

Abstract

Platinum dissolution in PEM fuel cells is an increasingly important indicator for the state-of-health and lifetime prediction of fuel cells in real applications. For this reason, portable online analysis tools are needed that can detect and quantify platinum with high sensitivity, selectivity, and [...] Read more.

Platinum dissolution in PEM fuel cells is an increasingly important indicator for the state-of-health and lifetime prediction of fuel cells in real applications. For this reason, portable online analysis tools are needed that can detect and quantify platinum with high sensitivity, selectivity, and accuracy in the product water of fuel cells. We validated the hanging mercury drop electrode (HMDE) and non-toxic bismuth film electrodes for the voltammetric determination of platinum for this purpose. Bismuth films were prepared by reductive deposition on both a glassy carbon solid state electrode and on a screen-printed electrode (film on-chip electrode). Both bismuth film electrodes could be successfully validated for the determination of platinum by adsorptive stripping voltammetry. An LOD of 7.9 μg/L and an LOQ of 29.1 μg/L were determined for the bismuth film solid state electrode, values of 22.5 μg/L for the LOD and of 79.0 μg/L for the LOQ were obtained for the bismuth film on-chip electrode. These numbers are still much higher than the results measured with the HMDE (LOD: 0.76 ng/L; LOQ: 2.8 ng/L) and are not sufficient to detect platinum in the product water of a fuel cell run in different load tests. The amount of dissolved platinum produced by a 100 W fuel cell stack upon dynamic and continuous high load cycling, respectively, was in the range of 2.9–4.1 ng/L, which could only be detected by the HMDE. Full article

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15 pages, 4829 KiB

Open AccessArticle

Coriaria nepalensis Stem Alkaloid as a Green Inhibitor for Mild Steel Corrosion in 1 M H₂SO₄ Solution

by Hari Bhakta Oli, Jamuna Thapa Magar, Nawaraj Khadka, Anup Subedee, Deval Prasad Bhattarai and Bishweshwar Pant

Electrochem 2022, 3(4), 713-727; https://doi.org/10.3390/electrochem3040047 - 1 Nov 2022

Cited by 7 | Viewed by 3081

Abstract

Using natural plant extracts on metallic substances is the most frequently studied green corrosion inhibition approach in corrosion science. In this work, Coriaria nepalensis Stem Alkaloid (CNSA) has been successfully extracted and characterized by qualitative chemical (Mayer’s and Dragendroff’s) test and spectroscopic (UV [...] Read more.

Using natural plant extracts on metallic substances is the most frequently studied green corrosion inhibition approach in corrosion science. In this work, Coriaria nepalensis Stem Alkaloid (CNSA) has been successfully extracted and characterized by qualitative chemical (Mayer’s and Dragendroff’s) test and spectroscopic (UV and FTIR) measurement. CNSA has been employed as a green inhibitor for Mild Steel (MS) corrosion subjected to 1 M H₂SO₄ solution. The corrosion inhibition efficacy has been assessed by weight loss and polarization measurement methods. The effect of inhibitor concentration, immersion period, and temperature on the inhibition efficiency for the MS immersed in both acid and inhibitor solutions of different concentrations have been investigated. The maximum inhibition effect observed for CNSA is 96.4% for MS immersed in 1000 ppm inhibitor solution for 6 h at 18 °C by the weight loss measurement method. Similarly, the polarization measurement method observed a 97.03% inhibition efficiency for MS immersed for 3 h. The adsorption of inhibitor molecules on the MS surface aligns with the Langmuir model. The free energy of adsorption obtained is −28.75 kJ/mol indicating physical adsorption dominance over chemical adsorption. These findings suggested that CNSA has greater potential as an efficient green inhibitor. Full article

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14 pages, 1199 KiB

Open AccessArticle

Theoretical Analysis of Mass Transfer Behavior in Fixed-Bed Electrochemical Reactors: Akbari-Ganji’s Method

by Ponraj Jeyabarathi, Lakshmanan Rajendran, Michael E. G. Lyons and Marwan Abukhaled

Electrochem 2022, 3(4), 699-712; https://doi.org/10.3390/electrochem3040046 - 17 Oct 2022

Cited by 13 | Viewed by 2385

Abstract

The theoretical model for a packed porous catalytic particle of the slab, cylindrical, and spherical geometries shape in fixed-bed electrochemical reactors is discussed. These particles have internal mass concentration and temperature gradients in endothermic or exothermic reactions. The model is based on a [...] Read more.

The theoretical model for a packed porous catalytic particle of the slab, cylindrical, and spherical geometries shape in fixed-bed electrochemical reactors is discussed. These particles have internal mass concentration and temperature gradients in endothermic or exothermic reactions. The model is based on a nonlinear reaction–diffusion equation containing a nonlinear term with an exponential relationship between intrinsic reaction rate and temperature. The porous catalyst particle’s concentration is obtained by solving the nonlinear equation using Akbari-Ganji’s method. A simple and closed-form analytical expression of the effectiveness factor for slab, cylindrical, and spherical geometries was also reported for all values of Thiele modulus, activation energy, and heat reaction. The accordance with results of a reliable numerical method shows the good accuracy that their approximate solution yields. Full article

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20 pages, 50286 KiB

Open AccessArticle

Acacia catechu Bark Alkaloids as Novel Green Inhibitors for Mild Steel Corrosion in a One Molar Sulphuric Acid Solution

by Rajaram Karki, Ajay Kumar Bajgai, Nawaraj Khadka, Onisha Thapa, Tanka Mukhiya, Hari Bhakta Oli and Deval Prasad Bhattarai

Electrochem 2022, 3(4), 668-687; https://doi.org/10.3390/electrochem3040044 - 11 Oct 2022

Cited by 9 | Viewed by 2909

Abstract

In situ corrosion inhibition in acid cleaning processes by using green inhibitors is at the forefront of corrosion chemistry. Plant extracts, especially alkaloids, are known to be good corrosion inhibitors against mild steel corrosion. In this research, alkaloids extracted from Acacia catechu have [...] Read more.

In situ corrosion inhibition in acid cleaning processes by using green inhibitors is at the forefront of corrosion chemistry. Plant extracts, especially alkaloids, are known to be good corrosion inhibitors against mild steel corrosion. In this research, alkaloids extracted from Acacia catechu have been used as green corrosion inhibitors for mild steel corrosion in a 1 M H₂SO₄ solution. Qualitative chemical tests and FTIR measurements have been performed to confirm the alkaloids in the extract. The inhibition efficiency of the extract has been studied by using weight-loss and potentiodynamic polarization methods. A weight-loss measurement has been adopted for the study of inhibitor’s concentration effect, with a variation employed to measure the inhibition efficiency for time and temperature. The weight-loss measurement revealed a maximum efficiency of 93.96% after 3 h at 28 °C for a 1000 ppm alkaloid solution. The 1000 ppm inhibitor is effective up to a temperature of 48 °C, with 84.39% efficiency. The electrochemical measurement results revealed that the alkaloids act as a mixed type of inhibitor. Inhibition efficiencies of 98.91% and 98.54% in the 1000 ppm inhibitor concentration solution for the as-immersed and immersed conditions, respectively, have been achieved. The adsorption isotherm has indicated the physical adsorption of alkaloids. Further, the spontaneous and endothermic adsorption processes have been indicated by the thermodynamic parameters. The results show that alkaloids extracted from the bark of Acacia catechu can be a promising green inhibitors for mild steel corrosion. Full article

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20 pages, 3278 KiB

Open AccessArticle

Experimental Validation of an Active Fault Tolerant Control Strategy Applied to a Proton Exchange Membrane Fuel Cell

by Etienne Dijoux, Nadia Yousfi Steiner, Michel Benne, Marie-Cécile Péra and Brigitte Grondin-Perez

Electrochem 2022, 3(4), 633-652; https://doi.org/10.3390/electrochem3040042 - 8 Oct 2022

Cited by 4 | Viewed by 2260

Abstract

Reliability of proton exchange membrane fuel cells (PEMFCs) is a major issue for large industrialization and commercialization. Indeed, performance can be degraded due to abnormal operating conditions, namely, faults, which lead either to a transient decay of the fuel cell performance or to [...] Read more.

Reliability of proton exchange membrane fuel cells (PEMFCs) is a major issue for large industrialization and commercialization. Indeed, performance can be degraded due to abnormal operating conditions, namely, faults, which lead either to a transient decay of the fuel cell performance or to permanent damage that cannot be recovered. The literature shows that long-time exposure to faults leads to fuel cell degradation. Therefore, it is necessary to use tools that can not only diagnose these faulty conditions, but also modify the fuel cell operations to recover a healthy operating point. For that purpose, one approach is the Active Fault Tolerant Control (AFTC) strategy which is composed of three functions. First, a diagnosis part allows fault detection and identification. Then a decision part, which is an algorithm aiming at finding a new operating point that mitigates the occurring fault. Finally, a control part applies the mitigation strategy established by the decision algorithm. The present work focuses on the decision part. and aims to bring a new contribution to PEMFCs reliability improvement and address water management issues, namely, the cell flooding and membrane drying out with the developed AFTC tool. The strategy is tested and validated on a single PEMFC cell and results are presented, analyzed, and discussed. Full article

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20 pages, 2176 KiB

Open AccessReview

Recent Advances in the Electro-Active Therapeutic Phytochemical-Based Sensors

by Mansi Gandhi, Khairunnisa Amreen and Brahm Kumar Tiwari

Electrochem 2022, 3(4), 613-632; https://doi.org/10.3390/electrochem3040041 - 8 Oct 2022

Cited by 2 | Viewed by 2427

Abstract

Naturally occurring phytonutrients/phyto-components are likely to have therapeutic values. These phyto-derived naturally occurring components, such as polyphenols, phenolics, flavonoids and phenolic acids have a hydrocarbon background with a polyphenolic ring, an ester bond with a polyphenolic ring, etc. Their structures play a critical [...] Read more.

Naturally occurring phytonutrients/phyto-components are likely to have therapeutic values. These phyto-derived naturally occurring components, such as polyphenols, phenolics, flavonoids and phenolic acids have a hydrocarbon background with a polyphenolic ring, an ester bond with a polyphenolic ring, etc. Their structures play a critical role in determining the chemical and physical attributes that define their activity/functions and roles. Owing to their chemical structure, most of them are electroactive. Thus, these phytochemicals can be used in the preparation of electrochemical sensors. Gaining an understanding of functional genotypical units using electrochemistry is a unique study. The feasibility of incorporating an array of biosensors into a fully-automated micro-electrochemical system is further explored. This review is intended to provide in-depth knowledge of biosensors’ applications based on/for Plantae kingdom and varieties. The discussion focuses primarily on the fields associated with the fully-automated micro-electrochemical system and appropriate methods for its advancement. The intended approach is to provide a selective outlook including the setbacks/shortcomings and usefulness of opting for the concerned technique. Full article

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32 pages, 5177 KiB

Open AccessReview

Effect of Components and Operating Conditions on the Performance of PEM Electrolyzers: A Review

by Khaja Wahab Ahmed, Myeong Je Jang, Moon Gyu Park, Zhongwei Chen and Michael Fowler

Electrochem 2022, 3(4), 581-612; https://doi.org/10.3390/electrochem3040040 - 23 Sep 2022

Cited by 27 | Viewed by 13170

Abstract

Hydrogen is considered to be the fuel of the future and with the advancement of fuel cell technology, there is a renewed interest in hydrogen production by the electrolysis of water. Among low-temperature water electrolysis options, polymer electrolyte membrane (PEM) electrolyzer is the [...] Read more.

Hydrogen is considered to be the fuel of the future and with the advancement of fuel cell technology, there is a renewed interest in hydrogen production by the electrolysis of water. Among low-temperature water electrolysis options, polymer electrolyte membrane (PEM) electrolyzer is the preferred choice due to its compact size, intermittent use, and connectivity with renewable energy. In addition, it is possible to generate compressed hydrogen directly in the PEM electrolyzer, thereby reducing the additional pressurization cost for hydrogen storage. The development of electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is a major focus of electrolysis research. Other components, such as PEMs, gas diffusion layers (GDL), and bipolar plates (BPs) have also received significant attention to enhance the overall efficiency of PEM electrolyzers. Improvements in each component or process of the PEM electrolyzer have a significant impact on increasing the energy efficiency of the electrolyzer. This work discusses various synthesis techniques to improve the dispersion of OER electrocatalyst and reducing catalyst loading for the PEM electrolyzer. Various techniques are discussed for the development of electrocatalysts, including nanostructured, core shell, and electrodeposition to deposit catalysts on GDL. The design and methodology of new and improved GDL are discussed along with the fabrication of gas diffusion electrodes and passivation techniques to reduce the oxidation of GDL. The passivation technique of BPs using Au and Pt is summarized for its effect on electrolysis efficiency. Finally, the optimization of various operating conditions for PEM electrolyzer are reviewed to improve the efficiency of the electrolyzer. Full article

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11 pages, 3197 KiB

Open AccessArticle

Lab-on-a-Chip Electrochemical Immunosensor Array Integrated with Microfluidics: Development and Characterisation

by Shifa Felemban, Patricia Vazquez, Thanih Balbaied and Eric Moore

Electrochem 2022, 3(4), 570-580; https://doi.org/10.3390/electrochem3040039 - 23 Sep 2022

Cited by 3 | Viewed by 2603

Abstract

Lab-on-a-chip has recently become an alternative for in situ monitoring for its portability and simple integration with an electrochemical immunoassay. Here, we present an electrochemical cell-on-a-chip configured in a three-electrode system to detect benzo(a)pyrene (BaP) in water. 11-Mercaptoundecanoic acid (MUA), a self-assembled monolayer [...] Read more.

Lab-on-a-chip has recently become an alternative for in situ monitoring for its portability and simple integration with an electrochemical immunoassay. Here, we present an electrochemical cell-on-a-chip configured in a three-electrode system to detect benzo(a)pyrene (BaP) in water. 11-Mercaptoundecanoic acid (MUA), a self-assembled monolayer (SAM), was used to modify a gold chip surface to reduce the randomness of antibody binding. A carboxylic acid group was activated with -ethyl-3-(3-dimethylaminopropyl) (EDC) in combination with N-hyrodsuccinimide (NHS) before antibody immobilisation. The mechanism of the electrochemical reactions on a gold surface and SAM formation were investigated by cyclic voltammetry and contact angle measurements. The data revealed a lower contact angle in the modified chip and a scan rate of 50 mV/s. Through the addition of modification layers and thiol end groups to the SAM, our design allowed the chip surface to became more insulated. All were tested by amperometric detection using the developed Q-sense system. This novel technique detected multiple samples, and completed the analysis reasonably quickly. While the integrated system proved successful in a lab setting, the aim of the research is to use this system for in situ analysis, which can be brought into a water environment to carry out tests with existing processes. In this way, any issues that may arise from an environmental setting can be rectified in an efficient manner. Full article

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21 pages, 3416 KiB

Open AccessArticle

Mass Transport Limitations in Electrochemical Conversion of CO₂ to Formic Acid at High Pressure

by Selvaraj Chinnathambi, Mahinder Ramdin and Thijs J. H. Vlugt

Electrochem 2022, 3(3), 549-569; https://doi.org/10.3390/electrochem3030038 - 2 Sep 2022

Cited by 7 | Viewed by 3667

Abstract

Mass transport of different species plays a crucial role in electrochemical conversion of CO

_{2}

due to the solubility limit of CO

_{2}

in aqueous electrolytes. In this study, we investigate the transport of CO

_{2}

and other ionic species through the electrolyte [...] Read more.

Mass transport of different species plays a crucial role in electrochemical conversion of CO

_{2}

due to the solubility limit of CO

_{2}

in aqueous electrolytes. In this study, we investigate the transport of CO

_{2}

and other ionic species through the electrolyte and the membrane, and its impact on the scale-up process of HCOO

^{-}

/HCOOH formation. The mass transport of ions to the electrode and the membrane is modelled at constant current density. The mass transport limitations of CO

_{2}

on the formation of HCOO

^{-}

/HCOOH is investigated at different pressures ranges from 5–40 bar. The maximum achievable partial current density of formate/formic acid is increased with increasing CO

_{2}

pressure. We use an ion exchange membrane model to understand the ion transport behaviour for both the monopolar and bipolar membranes. The cation exchange (CEM) and anion exchange membrane (AEM) model show that ion transport is limited by the electrolyte salt concentrations. For 0.1 M KHCO

_{3}

, the AEM reaches the limiting current density more quickly than the CEM. For the BPM model, ion transport across the diffusion layer on either side of the BPM is also included to understand the concentration polarization across the BPM. The model revealed that the polarization losses across the bipolar membrane depend on the pH of the electrolyte used for the CO

_{2}

reduction reaction (CO₂RR). The polarization loss on the anolyte side decreases with an increasing pH, while, on the cathode side, it increases with increasing catholyte pH. With this combined model for the electrode reactions and the membrane transport, we are able to account for the various factors influencing the polarization losses in the CO

_{2}

electrolyzer. To complete the analysis, we simulated the full cell polarization curve and fitted with the experimental data. Full article

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11 pages, 2116 KiB

Open AccessArticle

Effect of Recombinant Antibodies and MIP Nanoparticles on the Electrical Behavior of Impedimetric Biorecognition Surfaces for SARS-CoV-2 Spike Glycoprotein: A Short Report

by Douglas Vieira Thomaz, Riccardo Goldoni, Gianluca Martino Tartaglia, Cosimino Malitesta and Elisabetta Mazzotta

Electrochem 2022, 3(3), 538-548; https://doi.org/10.3390/electrochem3030037 - 2 Sep 2022

Cited by 6 | Viewed by 2905

Abstract

Electrochemical immunosensors are often described as innovative strategies to tackle urgent epidemiological needs, such as the detection of SARS-CoV-2 main biomarker, the spike glycoprotein. Nevertheless, there is a great variety of receptors, especially recombinant antibodies, that can be used to develop these biosensing [...] Read more.

Electrochemical immunosensors are often described as innovative strategies to tackle urgent epidemiological needs, such as the detection of SARS-CoV-2 main biomarker, the spike glycoprotein. Nevertheless, there is a great variety of receptors, especially recombinant antibodies, that can be used to develop these biosensing platforms, and very few reports compare their suitability in analytical device design and their sensing performances. Therefore, this short report targeted a brief and straightforward investigation of the performance of different impedimetric biorecognition surfaces (BioS) for SARS-CoV-2, which were crafted from three commonly reported recombinant antibodies and molecularly-imprinted polymer (MIP) nanoparticles (nanoMIP). The selected NanoMIP were chosen due to their reported selectivity to the receptor binding domain (RBD) of SARS-CoV-2 spike glycoprotein. Results showed that the surface modification protocol based on MUDA and crosslinking with EDC/NHS was successful for the anchoring of each tested receptor, as the semicircle diameter of the Nyquist plots of EIS increased upon each modification, which suggests the increase of R_ct due to the binding of dielectric materials on the conductive surface. Furthermore, the type of monoclonal antibody used to craft the BioS and the artificial receptors led to very distinct responses, being the RBD5305 and the NanoMIP-based BioS the ones that showcased the highest increment of signal in the conditions herein reported, which suggests their adequacy in the development of impedimetric immunosensors for SARS-CoV-2 spike glycoprotein. Full article

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18 pages, 3986 KiB

Open AccessReview

Recent Insight in Transition Metal Anchored on Nitrogen-Doped Carbon Catalysts: Preparation and Catalysis Application

by Boyang Li, Lihua Zhang, Jianrui Zhang and Yaqiong Su

Electrochem 2022, 3(3), 520-537; https://doi.org/10.3390/electrochem3030036 - 1 Sep 2022

Cited by 9 | Viewed by 2934

Abstract

The design and preparation of novel, high-efficiency, and low-cost heterogeneous catalysts are important topics in academic and industry research. In the past, inorganic materials, metal oxide, and carbon materials were used as supports for the development of heterogeneous catalysts due to their excellent [...] Read more.

The design and preparation of novel, high-efficiency, and low-cost heterogeneous catalysts are important topics in academic and industry research. In the past, inorganic materials, metal oxide, and carbon materials were used as supports for the development of heterogeneous catalysts due to their excellent properties, such as high specific surface areas and tunable porous structures. However, the properties of traditional pristine carbon materials cannot keep up with the sustained growth and requirements of industry and scientific research, since the introduction of nitrogen atoms into carbon materials may significantly enhance a variety of their physicochemical characteristics, which gradually become appropriate support for synthesizing supported transition metal catalysts. In the past several decades, the transition metal anchored on nitrogen-doped carbon catalysts has attracted a tremendous amount of interest as potentially useful catalysts for diverse chemical reactions. Compared with original carbon support, the doping of nitrogen atoms can significantly regulate the physicochemical properties of carbon materials and allow active metal species uniformly dispersed on the support. The various N species in support also play a critical role in accelerating the catalytic performance in some reactions. Besides, the interaction between support and transition metal active sites can offer an anchor site to stabilize metal species during the preparation process and then improve reaction performance, atomic utilization, and stability. In this review, we highlight the recent advances and the remaining challenges in the preparation and application of transition metal anchored on nitrogen-doped carbon catalysts. Full article

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13 pages, 5738 KiB

Open AccessArticle

Three-Dimensional Hybrid Nanostructures of Fe₃O₄ Nanoparticles/Vertically-Aligned Carbon Nanotubes for High-Performance Supercapacitors

by Bin Zhao

Electrochem 2022, 3(3), 507-519; https://doi.org/10.3390/electrochem3030035 - 26 Aug 2022

Cited by 2 | Viewed by 1946

Abstract

A three-dimensional (3D) hybrid nanostructure of Fe₃O₄ nanoparticles uniformly anchored on vertically-aligned carbon nanotubes (VACNTs) was fabricated by a facile two-step method. Assisted by supercritical carbon dioxide (SCCO₂), the Fe precursor was firstly absorbed on CNT surface and [...] Read more.

A three-dimensional (3D) hybrid nanostructure of Fe₃O₄ nanoparticles uniformly anchored on vertically-aligned carbon nanotubes (VACNTs) was fabricated by a facile two-step method. Assisted by supercritical carbon dioxide (SCCO₂), the Fe precursor was firstly absorbed on CNT surface and then transformed into Fe₃O₄ nanoparticles by vacuum thermal annealing. Owing to the synergetic effects of well-distributed Fe₃O₄ nanoparticles (~7 nm) and highly conductive VACNTs, the hybrid electrode exhibits a high specific capacitance of 364.2 F g⁻¹ at 0.5 A g⁻¹ within the potential range from −0.9 to +0.1 V in Na₂SO₃ electrolyte and an excellent cycling stability of 84.8% capacitance retention after 2000 cycles at a current density of 4 A/g. This 3D hybrid architecture consisting of aligned CNTs and pseudocapacitive metal oxide may be a promising electrode for high-performance supercapacitors. Full article

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13 pages, 1345 KiB

Open AccessArticle

Modelling of Irreversible Homogeneous Reaction on Finite Diffusion Layers

by Singaravel Anandhar Salai Sivasundari, Rathinam Senthamarai, Mohan Chitra Devi, Lakshmanan Rajendran and Michael E. G. Lyons

Electrochem 2022, 3(3), 479-491; https://doi.org/10.3390/electrochem3030033 - 26 Aug 2022

Cited by 4 | Viewed by 2085

Abstract

The mathematical model proposed by Chapman and Antano (Electrochimica Acta, 56 (2010), 128–132) for the catalytic electrochemical–chemical (EC’) processes in an irreversible second-order homogeneous reaction in a microelectrode is discussed. The mass-transfer boundary layer neighbouring an electrode can contribute to the electrode’s measured [...] Read more.

The mathematical model proposed by Chapman and Antano (Electrochimica Acta, 56 (2010), 128–132) for the catalytic electrochemical–chemical (EC’) processes in an irreversible second-order homogeneous reaction in a microelectrode is discussed. The mass-transfer boundary layer neighbouring an electrode can contribute to the electrode’s measured AC impedance. This model can be used to analyse membrane-transport studies and other instances of ionic transport in semiconductors and other materials. Two efficient and easily accessible analytical techniques, AGM and DTM, were used to solve the steady-state non-linear diffusion equation’s infinite layers. Herein, we present the generalized approximate analytical solution for the solute, product, and reactant concentrations and current for the small experimental values of kinetic and diffusion parameters. Using the Matlab/Scilab program, we also derive the numerical solution to this problem. The comparison of the analytical and numerical/computational results reveals a satisfactory level of agreement. Full article

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16 pages, 2461 KiB

Open AccessArticle

Carbon-α-Fe₂O₃ Composite Active Material for High-Capacity Electrodes with High Mass Loading and Flat Current Collector for Quasi-Symmetric Supercapacitors

by Maedeh Najafi, Sebastiano Bellani, Valerio Galli, Marilena Isabella Zappia, Ahmad Bagheri, Milad Safarpour, Hossein Beydaghi, Matilde Eredia, Lea Pasquale, Riccardo Carzino, Simone Lauciello, Jaya-Kumar Panda, Rosaria Brescia, Luca Gabatel, Vittorio Pellegrini and Francesco Bonaccorso

Electrochem 2022, 3(3), 463-478; https://doi.org/10.3390/electrochem3030032 - 23 Aug 2022

Cited by 12 | Viewed by 3019

Abstract

In this work, we report the synthesis of an active material for supercapacitors (SCs), namely α-Fe₂O₃/carbon composite (C-Fe₂O₃) made of elongated nanoparticles linearly connected into a worm-like morphology, by means of electrospinning followed by a [...] Read more.

In this work, we report the synthesis of an active material for supercapacitors (SCs), namely α-Fe₂O₃/carbon composite (C-Fe₂O₃) made of elongated nanoparticles linearly connected into a worm-like morphology, by means of electrospinning followed by a calcination/carbonization process. The resulting active material powder can be directly processed in the form of slurry to produce SC electrodes with mass loadings higher than 1 mg cm⁻² on practical flat current collectors, avoiding the need for bulky porous substrate, as often reported in the literature. In aqueous electrolyte (6 M KOH), the so-produced C-Fe₂O₃ electrodes display capacity as high as ~140 mAh g⁻¹ at a scan rate of 2 mV s⁻¹, while showing an optimal rate capability (capacity of 32.4 mAh g⁻¹ at a scan rate of 400 mV s⁻¹). Thanks to their poor catalytic activity towards water splitting reactions, the electrode can operate in a wide potential range (−1.6 V–0.3 V vs. Hg/HgO), enabling the realization of performant quasi-symmetric SCs based on electrodes with the same chemical composition (but different active material mass loadings), achieving energy density approaching 10 Wh kg⁻¹ in aqueous electrolytes. Full article

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12 pages, 1682 KiB

Open AccessArticle

A Novel Label-Free Electrochemical Immunosensor Based on a Self-Assembled Monolayer-Modified Electrode for Polychlorinated Biphenyl (PCB) in Environmental Analysis

by Samia Alsefri, Thanih Balbaied, Ibtihaj Albalawi, Hanan Alatawi and Eric Moore

Electrochem 2022, 3(3), 451-462; https://doi.org/10.3390/electrochem3030031 - 22 Aug 2022

Cited by 1 | Viewed by 2678

Abstract

PCBs (polychlorinated biphenyls) are a very large group of organic compounds that have between two and ten chlorine atoms attached to the biphenyl. These compounds have an acute impact as environmental pollutants, causing cancer and other adverse health effects in humans. It is [...] Read more.

PCBs (polychlorinated biphenyls) are a very large group of organic compounds that have between two and ten chlorine atoms attached to the biphenyl. These compounds have an acute impact as environmental pollutants, causing cancer and other adverse health effects in humans. It is therefore imperative to develop techniques for the cost-effective detection of PCBs at very low concentrations in ecosystems. In this paper, a novel label-free, indirect, competitive electrochemical immunosensor was first developed with a PCB-BSA conjugate. It is shown herein to compete with free PCBs for binding to the anti-PCB polyclonal primary antibody (IgY). Then, we used a secondary antibody to enhance the sensitivity of the sensor for the detection of PCB in a sample. It has been successfully immobilized on an 11-mercaptoundecanoic acid (11-MUA)-modified gold electrode via a carbodiimide-coupling reaction using cross-linking 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) on the electrode surface. The immunosensor was investigated by cyclic voltammetry and differential pulse voltammetry in a standard solution of [Fe(CN)₆]^3−/4−. A linear range of 0.011–220 ng/mL⁻¹ and a limit of detection (LOD) of 0.11 ng/mL⁻¹ for PCBs detection were achieved by the developed immunosensor, showing advantages over conventional assays. The novel label-free electrochemical immunosensor discussed in this paper is a solution for simple, rapid, cost-effective sample screening in a portable, disposable format. The proposed immunosensor has good sensitivity, and it can prove to be an adequate real-time monitoring solution for PCBs in soil samples or other samples. Full article

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17 pages, 1916 KiB

Open AccessReview

Electrochemical Profiling of Plants

by Mansi Gandhi and Khairunnisa Amreen

Electrochem 2022, 3(3), 434-450; https://doi.org/10.3390/electrochem3030030 - 4 Aug 2022

Cited by 10 | Viewed by 3591

Abstract

The profiling, or fingerprinting, of distinct varieties of the Plantae kingdom is based on the bioactive ingredients, which are systematically segregated to perform their detailed analysis. The secondary products portray a pivotal role in defining the ecophysiology of distinct plant species. There is [...] Read more.

The profiling, or fingerprinting, of distinct varieties of the Plantae kingdom is based on the bioactive ingredients, which are systematically segregated to perform their detailed analysis. The secondary products portray a pivotal role in defining the ecophysiology of distinct plant species. There is a crucial role of the profiling domain in understanding the various features, characteristics, and conditions related to plants. Advancements in variable technologies have contributed to the development of highly specific sensors for the non-invasive detection of molecules. Furthermore, many hyphenated techniques have led to the development of highly specific integrated systems that allow multiplexed detection, such as high-performance liquid chromatography, gas chromatography, etc., which are quite cumbersome and un-economical. In contrast, electrochemical sensors are a promising alternative which are capable of performing the precise recognition of compounds due to efficient signal transduction. However, due to a few bottlenecks in understanding the principles and non-redox features of minimal metabolites, the area has not been explored. This review article provides an insight to the electrochemical basis of plants in comparison with other traditional approaches and with necessary positive and negative outlooks. Studies consisting of the idea of merging the fields are limited; hence, relevant non-phytochemical reports are included for a better comparison of reports to broaden the scope of this work. Full article

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18 pages, 3466 KiB

Open AccessArticle

A Biodegradable Polymer-Based Plastic Chip Electrode as a Current Collector in Supercapacitor Application

by Kirti, Rajeev Gupta and Divesh N. Srivastava

Electrochem 2022, 3(3), 379-396; https://doi.org/10.3390/electrochem3030026 - 7 Jul 2022

Cited by 6 | Viewed by 3266

Abstract

Here, we report the performance of a biodegradable polymer-based Plastic chip Electrode (PCE) as a current collector in supercapacitor applications. Its production was evaluated using two redox materials (conducting polymers polyaniline and poly(3,4-ethylene dioxythiophene)) and a layered material, rGO. The conducting polymers were [...] Read more.

Here, we report the performance of a biodegradable polymer-based Plastic chip Electrode (PCE) as a current collector in supercapacitor applications. Its production was evaluated using two redox materials (conducting polymers polyaniline and poly(3,4-ethylene dioxythiophene)) and a layered material, rGO. The conducting polymers were directly deposited over the Eco-friendly PCE (EPCE) using the galvanostatic method. The rGO was prepared in the conventional way and loaded over the EPCE using a binder. Both conducting polymers and rGO showed proper specific capacitance compared to previous studies with regular current collectors. Electrodes were found highly stable during experiments in high acidic medium. The supercapacitive performance was evaluated with cyclic voltammetry, charge–discharge measurements, and impedance spectroscopy. The supercapacitive materials were also characterized for their electrical and microscopic properties. Polyaniline and PEDOT were deposited over EPCEs showing >150 Fg⁻¹ and >120 Fg⁻¹ specific capacitance, respectively, at 0.5 Ag⁻¹. rGO continued to show higher particular capacitance of >250 Fg⁻¹ with excellent charge–discharge cyclic stability. The study concludes that EPCs can be used as promising electrodes for electrical energy storage applications. Full article

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18 pages, 1471 KiB

Open AccessArticle

Modelling of Biotrickling Filters for Treatment of NO_x Analytical Expressions for the NO_x Concentration in Both Gas and Biofilm Phases

by Ramasamy Umadevi, Ponraj Jeyabarathi, Kothandapani Venugopal, Michael E. G. Lyons and Lakshmanan Rajendran

Electrochem 2022, 3(3), 361-378; https://doi.org/10.3390/electrochem3030025 - 5 Jul 2022

Cited by 1 | Viewed by 2078

Abstract

A mathematical model of an ideal biotrickling filter (BF) system that inoculates a recently identified strain of Chelatococcus daeguensis TAD1 and brings about efficient nitrogen oxide treatment is discussed. The proposed model is based on nonlinear mass transport equations at the gas–biofilm interface. [...] Read more.

A mathematical model of an ideal biotrickling filter (BF) system that inoculates a recently identified strain of Chelatococcus daeguensis TAD1 and brings about efficient nitrogen oxide treatment is discussed. The proposed model is based on nonlinear mass transport equations at the gas–biofilm interface. Using Akbari–Ganji’s technique, approximate analytical expressions for the nitric oxide concentration in the gaseous and biofilm phases were developed for all feasible system parameters. In addition, to investigate the dynamic behaviour of the system, a numerical analysis of the problem is provided using MATLAB tools. To demonstrate this new approach, graphical data are provided and quantitatively discussed. This theoretical result has good agreement with the numerical simulation (MATLAB) results for the experimental values of parameters. Full article

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14 pages, 2667 KiB

Open AccessArticle

Reactivities of Hydroxycinnamic Acid Derivatives Involving Caffeic Acid toward Electrogenerated Superoxide in N,N-Dimethylformamide

by Tatsushi Nakayama and Bunji Uno

Electrochem 2022, 3(3), 347-360; https://doi.org/10.3390/electrochem3030024 - 5 Jul 2022

Cited by 5 | Viewed by 2865

Abstract

Reactivity of (2E)-3-(3,4-dihydroxyphenyl)prop-2-enoic acid (caffeic acid), classified as a hydroxycinnamic acid (HCA) derivative, toward electrogenerated superoxide radical anion (O₂^•−) was investigated through cyclic voltammetry, in situ electrolytic electron spin resonance spectrometry, and in situ electrolytic ultraviolet–visible spectrometry in [...] Read more.

Reactivity of (2E)-3-(3,4-dihydroxyphenyl)prop-2-enoic acid (caffeic acid), classified as a hydroxycinnamic acid (HCA) derivative, toward electrogenerated superoxide radical anion (O₂^•−) was investigated through cyclic voltammetry, in situ electrolytic electron spin resonance spectrometry, and in situ electrolytic ultraviolet–visible spectrometry in N,N-dimethylformamide (DMF), aided by density functional theory (DFT) calculations. The quasi-reversible redox of dioxygen/O₂^•− is modified in the presence of caffeic acid, suggesting that O₂^•− is scavenged by caffeic acid through proton-coupled electron transfer. The reactivities of caffeic acid toward O₂^•− are mediated by the ortho-diphenol (catechol) moiety rather than by the acryloyl group, as experimentally confirmed in comparative analyses with other HCAs. The electrochemical and DFT results in DMF suggested that a concerted two-proton-coupled electron transfer mechanism proceeds via the catechol moiety. This mechanism embodies the superior kinetics of O₂^•− scavenging by caffeic acid. Full article

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13 pages, 1627 KiB

Open AccessArticle

Modelling the Current Response and Sensitivity of Oxidase Enzyme Electrodes, Monitored Amperometrically by the Consumption of Oxygen

by Pandy Pirabaharan, M. Chitra Devi, Rajagopal Swaminathan, Lakshmanan Rajendran and Michael E. G. Lyons

Electrochem 2022, 3(2), 309-321; https://doi.org/10.3390/electrochem3020021 - 2 Jun 2022

Cited by 3 | Viewed by 2329

Abstract

Biosensor behaviour is characterised by non-linear differential equations that describe well-defined physical, chemical, and biological processes. Mathematical modelling of these biosensors is highly desirable since they have many applications. These models enable the prediction of a variety of their properties. In this study, [...] Read more.

Biosensor behaviour is characterised by non-linear differential equations that describe well-defined physical, chemical, and biological processes. Mathematical modelling of these biosensors is highly desirable since they have many applications. These models enable the prediction of a variety of their properties. In this study, the cyclic conversion of the substrate in an amperometric biosensor with an oxidase enzyme membrane electrode is studied using a mathematical model. The governing parameters for the Michaelis–Menten kinetics of enzymatic reactions are the enzyme kinetic and diffusion rates across the enzymatic layer. In this paper, we solved the non-linear equations analytically and numerically for all experimental values of parameters. This problem is simulated in MATLAB^® v2016b software using the PDE solver. Our analytical solutions are compared to simulation results to validate the proposed model. Full article

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9 pages, 1870 KiB

Open AccessCommunication

Efficacy of the PlasmaShield^®, a Non-Thermal, Plasma-Based Air Purification Device, in Removing Airborne Microorganisms

by Harriet Whiley, Thilini P. Keerthirathne, Emma J. Kuhn, Muhammad Atif Nisar, Alex Sibley, Peter Speck and Kirstin E. Ross

Electrochem 2022, 3(2), 276-284; https://doi.org/10.3390/electrochem3020019 - 1 Jun 2022

Cited by 3 | Viewed by 3305

Abstract

Airborne microorganisms play a significant role in the transmission of infectious diseases. As such, improving indoor microbial air quality can enhance infection control in numerous settings. This study examined the efficacy of the PlasmaShield^® air purification device to remove airborne microorganisms under [...] Read more.

Airborne microorganisms play a significant role in the transmission of infectious diseases. As such, improving indoor microbial air quality can enhance infection control in numerous settings. This study examined the efficacy of the PlasmaShield^® air purification device to remove airborne microorganisms under laboratory conditions. Pure cultures of model microorganisms at varying concentrations were aerosolized using a 1-jet Collison nebulizer through stainless-steel removable piping prior to reaching the PlasmaShield^® device. The surviving microorganisms were captured using the Staplex^® MBS-6 Six Stage Microbial Air Sampler and enumerated via culture on agar plates. The positive-hole-corrected colony/plaque-forming units were compared with the negative control (microorganisms aerosolized through an empty PlasmaShield^® casing). The PlasmaShield^® statistically significantly (p < 0.05) reduced airborne Escherichia coli, Staphylococcus epidermidis, Bacteriophage MS2 and Cladosporium sp. compared with the negative control. The maximum removal achieved was estimated to be 4 × log₁₀E. coli (99.99% removal), 4 × log₁₀S. epidermidis (99.97% removal), 7 × log₁₀ MS2 (99.99998% removal) and 5 × log₁₀Cladosporium sp. (99.999% removal). Scanning electron microscope images of the surviving microorganisms showed that the PlasmaShield^® damaged the cell membrane of these model microorganisms. This study provides proof-of-concept evidence to support the use of this technology to improve indoor microbial air quality. Full article

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17 pages, 6275 KiB

Open AccessArticle

Performance Study on the Effect of Coolant Inlet Conditions for a 20 Ah LiFePO₄ Prismatic Battery with Commercial Mini Channel Cold Plates

by Jeevan Jaidi, Sandeep Dattu Chitta, Chaithanya Akkaldevi, Satyam Panchal, Michael Fowler and Roydon Fraser

Electrochem 2022, 3(2), 259-275; https://doi.org/10.3390/electrochem3020018 - 25 May 2022

Cited by 42 | Viewed by 3246

Abstract

Rechargeable Li-ion batteries are widely used in renewable energy storage and automotive powertrain systems, and therefore, an efficient thermal management system is imperative for maximum battery life and safety. Battery heat generation and dissipation rates primarily depend on the battery surface temperatures, which [...] Read more.

Rechargeable Li-ion batteries are widely used in renewable energy storage and automotive powertrain systems, and therefore, an efficient thermal management system is imperative for maximum battery life and safety. Battery heat generation and dissipation rates primarily depend on the battery surface temperatures, which are affected by the coolant system design and coolant inlet conditions. In this paper, a two-way coupled electrochemical-thermal simulation with selected experimental validation has been performed and analyzed the effect of water coolant inlet conditions on the effectiveness of commercial mini-channel cold-plates for 20 Ah LiFePO₄ prismatic batteries. Three coolant inlet temperatures (25–45 °C) and four flow rates (150–600 mL/min) are tested at three different discharge rates (2–4 C) and the performance of coolant system design has been analyzed in terms of battery peak (maximum) temperature and temperature difference (i.e., non-uniformity) across the battery. The predicted results indicate that the coolant flow rate has a profound effect on the battery temperature non-uniformity, while the coolant inlet temperature has a significant effect on the battery peak temperature. At high coolant flow rates, the battery surface temperature difference is within the acceptable range (ΔT < 5 °C), but the maximum temperatures are high at all discharge rates. Further, at the low coolant inlet temperature of 25 °C and the high coolant flow rate of 600 mL/min, the battery temperature rise at the top and bottom locations during the constant current discharge process is high, indicating that the battery heat generation rate is high at a low coolant inlet temperature. Full article

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11 pages, 2224 KiB

Open AccessReview

Electrochemical Reduction and Voltammetric Sensing of Lindane at the Carbon (Glassy and Pencil) Electrodes

by Nibedita Swain, Isha Soni, Pankaj Kumar and Gururaj Kudur Jayaprakash

Electrochem 2022, 3(2), 248-258; https://doi.org/10.3390/electrochem3020017 - 13 May 2022

Cited by 3 | Viewed by 2947

Abstract

In the agricultural field, pesticides are used tremendously to shield our crops from insects, weeds, and diseases. Only a small percentage of pesticides employed reach their intended target, and the remainder passes through the soil, contaminating ground and surface-water supplies, damaging the crop [...] Read more.

In the agricultural field, pesticides are used tremendously to shield our crops from insects, weeds, and diseases. Only a small percentage of pesticides employed reach their intended target, and the remainder passes through the soil, contaminating ground and surface-water supplies, damaging the crop fields, and ultimately harming the crop, including humans and other creatures. Alternative approaches for pesticide measurement have recently received a lot of attention, thanks to the growing interest in the on-site detection of analytes using electrochemical techniques that can replace standard chromatographic procedures. Among all organochlorine pesticides such as gamma-lindane are hazardous, toxic, and omnipresent contaminants in the environment. Here, in this review, we summarize the different ways of the gamma-lindane detection, performing the electrochemical techniques viz cyclic, differential, square wave voltammetry, and amperometry using various bare and surface-modified glassy carbon and pencil carbon electrodes. The analytical performances are reported as the limit of detection 18.8 nM (GCE–AONP–PANI–SWCNT), 37,000 nM (GCE), 38.1 nM (Bare HBPE), 21.3 nM (Nyl-MHBPE); percentage recovery is 103%. Full article

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9 pages, 2492 KiB

Open AccessArticle

Chitosan/Gold Nanoparticles Nanocomposite Film for Bisphenol A Electrochemical Sensing

by Leandro A. Almeida, Bruno V. M. Rodrigues, Debora T. Balogh, Rafaela C. Sanfelice, Luiza A. Mercante, Amanda F. Frade-Barros and Adriana Pavinatto

Electrochem 2022, 3(2), 239-247; https://doi.org/10.3390/electrochem3020016 - 4 May 2022

Cited by 6 | Viewed by 2891

Abstract

Bisphenol A (BPA) is considered an endocrine-disrupting compound and can cause toxicological effects, even at low doses. The development of sensitive and reliable sensors that would allow the detection of such contaminant is highly pursued. Herein, we report an electrochemical sensing strategy based [...] Read more.

Bisphenol A (BPA) is considered an endocrine-disrupting compound and can cause toxicological effects, even at low doses. The development of sensitive and reliable sensors that would allow the detection of such contaminant is highly pursued. Herein, we report an electrochemical sensing strategy based on a simple and low-cost nanocomposite film sensor platform for BPA detection. The platform was developed by modifying a fluorine-doped tin oxide (FTO) electrode with layer-by-layer (LbL) films of chitosan (Chi) and gold nanoparticles functionalized with a polythiophene derivative (AuNPs:PTS). The growth of the Chi/AuNPs:PTS LbL films was monitored by UV–Vis spectroscopy. Electrochemical characterization revealed that the three-bilayer film exhibited the highest electrocatalytic performance and differential-pulse voltammetry (DPV) measurements demonstrated that the modified electrode was suitable for BPA detection through a quasi-reversible and adsorption-controlled electrochemical oxidation and reduction process. The developed sensor exhibited a linear response range from 0.4 to 20 μmol L⁻¹, with a detection limit of 0.32 μmol L⁻¹. The sensor showed good reproducibility with relative standard deviations of 2.12% and 3.73% to intra- and inter-electrode, respectively. Furthermore, the platform demonstrated to be suitable to detect BPA in real water samples, as well as selective for BPA detection in solutions with 100-fold excess of common interfering compounds. Full article

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10 pages, 4965 KiB

Open AccessArticle

N-Graphene Sheet Stacks/Cu Electrocatalyst for CO₂ Reduction to Ethylene

by Peteris Lesnicenoks, Ainars Knoks, Sergei Piskunov, Laimonis Jekabsons and Janis Kleperis

Electrochem 2022, 3(2), 229-238; https://doi.org/10.3390/electrochem3020015 - 1 May 2022

Cited by 3 | Viewed by 3149

Abstract

Renewable energy resources (wind, solar) are unpredictable, so it is wise to store the electricity they generate in an energy carrier X. Various PtX (power to useful energy-intensive raw material such as hydrogen, synthetic natural gas, fuel) applications have been proposed. At the [...] Read more.

Renewable energy resources (wind, solar) are unpredictable, so it is wise to store the electricity they generate in an energy carrier X. Various PtX (power to useful energy-intensive raw material such as hydrogen, synthetic natural gas, fuel) applications have been proposed. At the heart of our work is widely used idea to convert residual CO₂ from biogas plant into higher hydrocarbons using electricity from renewables (e.g., sun, wind, hydro). The specific goal is to produce ethylene-highly demanded hydrocarbon in plastics industry. The process itself is realised on electrocatalytic carbon/copper cathode which must be selective to reaction: 2CO₂ + 12e⁻ + 12H⁺→C₂H₄ + 4H₂O. We propose a bottom-up approach to build catalyst from the smallest particles-graphene sheet stacks (GSS) coated with metallic copper nanocrystals. Composite GSS-Cu structure functions as a CO₂ and proton absorber, facilitating hydrogenation and carbon–carbon coupling reactions on Cu-nanocluster/GSS for the formation of C₂H₄. In our design electrocatalytic electrode is made from nitrogen-doped graphene sheet stacks coated with copper nanostructures. The N-GSSitself can be drop-casted or electrophoretically incorporated onto the carbon paper and gas diffusion electrode. Electrochemical deposition method was recognized as successful and most promising to grow Cu nanocrystals on N-GSS incorporated in conducting carbon substrate. Gaseous products from CO₂ electro-catalytic reformation on the cathode were investigated by mass-spectrometer but the electrode surface was analysed by SEM/EDS and XRD methods. Full article

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14 pages, 10292 KiB

Open AccessArticle

Alkaloid of Rhynchostylis retusa as Green Inhibitor for Mild Steel Corrosion in 1 M H₂SO₄ Solution

by Amrita Chapagain, Debendra Acharya, Anju Kumari Das, Kisan Chhetri, Hari Bhakta Oli and Amar Prasad Yadav

Electrochem 2022, 3(2), 211-224; https://doi.org/10.3390/electrochem3020013 - 18 Apr 2022

Cited by 20 | Viewed by 3442

Abstract

Alkaloids are aromatic hydrocarbons with nitrogen as heteroelements in the ring structure that are responsible for bonding with the metal surface and help to reduce corrosion of metals such as mild steel (MS) in an acidic medium. In this study, the alkaloid of [...] Read more.

Alkaloids are aromatic hydrocarbons with nitrogen as heteroelements in the ring structure that are responsible for bonding with the metal surface and help to reduce corrosion of metals such as mild steel (MS) in an acidic medium. In this study, the alkaloid of Rhynchostylis retusa (RR) was extracted by solvent extraction method and confirmed by chemical test as well as FTIR spectroscopic test. Extracted alkaloids were tested as green inhibitors for the MS corrosion in a 1.0 M H₂SO₄ solution. The inhibition efficiency (IE) of alkaloid extracts of RR was studied by the weight loss measurement method and electrochemical polarization method. Results showed that the maximum IE in the gravimetric method was 87.51% in 1000 ppm solution at 6 h immersion time. Open circuit potential (OCP) and potentiodynamic polarization results indicated that the extracted alkaloids acted as a mixed type of inhibitor. IE by polarization method was found to be 93.24% for the sample immersed for 6 h. The temperature effect study reveals that inhibitors can work only below 35 °C. Alkaloids of RR can be successfully extracted and used as corrosion inhibitors for MS in an acidic medium below 35 °C. Full article

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13 pages, 11118 KiB

Open AccessArticle

Electrodeposition and Micro-Mechanical Property Characterization of Nickel–Cobalt Alloys toward Design of MEMS Components

by Yiming Jiang, Chun-Yi Chen, Xun Luo, Daisuke Yamane, Masanori Mizoguchi, Osamu Kudo, Ryu Maeda, Masato Sone and Tso-Fu Mark Chang

Electrochem 2022, 3(2), 198-210; https://doi.org/10.3390/electrochem3020012 - 13 Apr 2022

Cited by 3 | Viewed by 2660

Abstract

Nickel–cobalt alloys were prepared by alloy electrodeposition with a sulfamate bath, and the mechanical properties on the micro-scale were evaluated for the application as micro-components in miniaturized electronic devices. Nickel bromide and a commercially available surface brightener were used as the additives. The [...] Read more.

Nickel–cobalt alloys were prepared by alloy electrodeposition with a sulfamate bath, and the mechanical properties on the micro-scale were evaluated for the application as micro-components in miniaturized electronic devices. Nickel bromide and a commercially available surface brightener were used as the additives. The cobalt content increased from 21.5 to 60.1 at.% after addition of nickel bromide into the bath, and the grain size refined from 21.1 to 13.2 nm when the surface brightener was used. The mechanical properties on the micro-scale were evaluated by micro-compression test using micro-pillar type specimens fabricated by a focused ion beam system to take the sample size effect into consideration. The yield strength of the nickel–cobalt alloy having an average grain size at 13.9 nm and cobalt content of 66.6 at.% reached 2.37 GPa, revealing influences from the sample size, grain boundary strengthening, and solid solution strengthening effects. Full article

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14 pages, 3056 KiB

Open AccessArticle

Ferrocene-Based Porous Organic Polymer (FPOP): Synthesis, Characterization and an Electrochemical Study

by Željko Petrovski, Mateus P. Moreira, Andreia F. M. Santos, Sunny K. S. Freitas, Noémi Jordão, Renata A. Maia, Ana V. M. Nunes, Luis C. Branco, Hugo Cruz and Pierre M. Esteves

Electrochem 2022, 3(1), 184-197; https://doi.org/10.3390/electrochem3010011 - 27 Feb 2022

Cited by 1 | Viewed by 3893

Abstract

Ferrocene-based porous organic polymers (FPOPs) were prepared from phenol-formaldehyde polymer (Bakelite) and phenol as starting materials; and two possible mechanisms for polymerization were discussed. Solid-state ¹³C CP-MAS NMR, FTIR, powder XRD, elemental analysis and ICP (Fe, Na, B) were performed to characterize [...] Read more.

Ferrocene-based porous organic polymers (FPOPs) were prepared from phenol-formaldehyde polymer (Bakelite) and phenol as starting materials; and two possible mechanisms for polymerization were discussed. Solid-state ¹³C CP-MAS NMR, FTIR, powder XRD, elemental analysis and ICP (Fe, Na, B) were performed to characterize the prepared materials. The two synthetic approaches produced polymers with different pore sizes: the FPOP synthesized through Bakelite presented a higher surface area (52 m² g⁻¹) when compared to the one obtained by the bottom-up polymerization from phenol (only 5 m² g⁻¹). Thermogravimetric analysis confirmed the thermal stability of the material, which decomposed at 350 °C. Furthermore, cyclic voltammetry (CV) of the new FPOP on modified electrodes, in ACN and 0.1 M TBAP as an electrolyte, showed fully reversible electron transfer, which is similar to that observed for the ferrocene probe dissolved in the same electrolyte. As a proof-of-concept for an electrochromic device, this novel material was also tested, with a color change detected between yellow/brownish coloration (reduced form) and green/blue coloration (oxidized form). The new hybrid FPOP seems very promising for material science, energy storage and electrochromic applications, as well as for plastic degradation. Full article

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41 pages, 187530 KiB

Open AccessReview

Graphene: Chemistry and Applications for Lithium-Ion Batteries

by Roshny Joy, Neethu T. M Balakrishnan, Akhila Das, Shimna Shafeek, Vijay Kumar Thakur, Karim Zaghib, Jabeen Fatima Manamkeri Jaffarali, Mogalahalli Venkatesh Venkatashamy Reddy and Prasanth Raghavan

Electrochem 2022, 3(1), 143-183; https://doi.org/10.3390/electrochem3010010 - 25 Feb 2022

Cited by 27 | Viewed by 9460

Abstract

In the present era, different allotropes of carbon have been discovered, and graphene is the one among them that has contributed to many breakthroughs in research. It has been considered a promising candidate in the research and academic fields, as well as in [...] Read more.

In the present era, different allotropes of carbon have been discovered, and graphene is the one among them that has contributed to many breakthroughs in research. It has been considered a promising candidate in the research and academic fields, as well as in industries, over the last decade. It has many properties to be explored, such as an enhanced specific surface area and beneficial thermal and electrical conductivities. Graphene is arranged as a 2D structure by organizing sp² hybridized C with alternative single and double bonds, providing an extended conjugation combining hexagonal ring structures to form a honeycomb structure. The precious structure and outstanding characteristics are the major reason that modern industry relies heavily on graphene, and it is predominantly applied in electronic devices. Nowadays, lithium-ion batteries (LIBs) foremostly utilize graphene as an anode or a cathode, and are combined with polymers to use them as polymer electrolytes. After three decades of commercialization of the lithium-ion battery, it still leads in consumer electronic society due to its higher energy density, wider operating voltages, low self-discharge, noble high-temperature performance, and fewer maintenance requirements. In this review, we aim to give a brief review of the domination of graphene and its applications in LIBs. Full article

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14 pages, 2304 KiB

Open AccessArticle

Hydrogen Bond Donors Influence on the Electrochemical Performance of Composite Graphene Electrodes/Deep Eutectic Solvents Interface

by Ana T. S. C. Brandão, Renata Costa, A. Fernando Silva and Carlos M. Pereira

Electrochem 2022, 3(1), 129-142; https://doi.org/10.3390/electrochem3010009 - 10 Feb 2022

Cited by 3 | Viewed by 3197

Abstract

The development of energy storage devices with better performance relies on the use of innovative materials and electrolytes, aiming to reduce the carbon footprint through the screening of low toxicity electrolytes and solvent-free electrode design protocols. The application of nanostructured carbon materials with [...] Read more.

The development of energy storage devices with better performance relies on the use of innovative materials and electrolytes, aiming to reduce the carbon footprint through the screening of low toxicity electrolytes and solvent-free electrode design protocols. The application of nanostructured carbon materials with high specific surface area, to prepare composite electrodes, is being considered as a promising starting point towards improving the power and energy efficiency of energy storage devices. Non-aqueous electrolytes synthesized using greener approaches with lower environmental impact make deep eutectic solvents (DES) promising alternatives for electrochemical energy storage and conversion applications. Accordingly, this work proposes a systematic study on the effect of the composition of DES containing a diol and an amide as HBD (hydrogen bond donor: 1,2-propylene glycol and urea), on the electrochemical performance of graphene and graphite composite electrodes/DES electrolyte interface. Glassy carbon (GC) was selected as the bare electrode material substrate to prepare the composite formulations since it provides an electrochemically reproducible surface. Gravimetric capacitance was measured for commercial graphene and commercial graphite/GC composite electrodes in contact with choline chloride, complexed with 1,2-propylene glycol, and urea as the HBD in 1:2 molar ratio. The electrochemical stability was followed by assessing the charge/discharge curves at 1, 2, and 4 A g⁻¹. For comparison purposes, a parallel study was performed using commercial graphite. A four-fold increase in gravimetric capacitance was obtained when replacing commercial graphite (1.70 F g⁻¹) by commercial graphene (6.19 F g⁻¹) in contact with 1,2-propylene glycol-based DES. When using urea based DES no significant change in gravimetric capacitance was observed when commercial graphite is replaced by commercial graphene. Full article

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25 pages, 4389 KiB

Open AccessReview

A Comprehensive Review on the Use of Metal–Organic Frameworks (MOFs) Coupled with Enzymes as Biosensors

by José E. da S. Souza, Gabriel P. de Oliveira, Jeferson Y. N. H. Alexandre, José G. L. Neto, Misael B. Sales, Paulo G. de S. Junior, André L. B. de Oliveira, Maria C. M. de Souza and José C. S. dos Santos

Electrochem 2022, 3(1), 89-113; https://doi.org/10.3390/electrochem3010006 - 1 Feb 2022

Cited by 39 | Viewed by 5964

Abstract

Several studies have shown the development of electrochemical biosensors based on enzymes immobilized in metal–organic frameworks (MOFs). Although enzymes have unique properties, such as efficiency, selectivity, and environmental sustainability, when immobilized, these properties are improved, presenting significant potential for several biotechnological applications. Using [...] Read more.

Several studies have shown the development of electrochemical biosensors based on enzymes immobilized in metal–organic frameworks (MOFs). Although enzymes have unique properties, such as efficiency, selectivity, and environmental sustainability, when immobilized, these properties are improved, presenting significant potential for several biotechnological applications. Using MOFs as matrices for enzyme immobilization has been considered a promising strategy due to their many advantages compared to other supporting materials, such as larger surface areas, higher porosity rates, and better stability. Biosensors are analytical tools that use a bioactive element and a transducer for the detection/quantification of biochemical substances in the most varied applications and areas, in particular, food, agriculture, pharmaceutical, and medical. This review will present novel insights on the construction of biosensors with materials based on MOFs. Herein, we have been highlighted the use of MOF for biosensing for biomedical, food safety, and environmental monitoring areas. Additionally, different methods by which immobilizations are performed in MOFs and their main advantages and disadvantages are presented. Full article

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19 pages, 4288 KiB

Open AccessArticle

Theoretical and Numerical Analysis of Nonlinear Processes in Amperometric Enzyme Electrodes with Cyclic Substrate Conversion

by Vinolyn Sylvia, Rajendran Joy Salomi, Lakshmanan Rajendran and Michael E. G. Lyons

Electrochem 2022, 3(1), 70-88; https://doi.org/10.3390/electrochem3010005 - 25 Jan 2022

Cited by 6 | Viewed by 3700

Abstract

A theoretical model of amperometric enzyme electrodes has been developed in which chemical amplification occurs in a single enzyme membrane via cyclic substrate conversion. The system is based on non-stationary diffusion equations with a nonlinear factor related to the Michaelis–Menten kinetics of the [...] Read more.

A theoretical model of amperometric enzyme electrodes has been developed in which chemical amplification occurs in a single enzyme membrane via cyclic substrate conversion. The system is based on non-stationary diffusion equations with a nonlinear factor related to the Michaelis–Menten kinetics of the enzymatic reaction. By solving the nonlinear equations using the AGM technique, simple analytical expressions of concentration substrate, product, and amperometric current response are derived. Further, biosensor sensitivity, resistance, and gain are obtained from the current. MATLAB programming was used to carry out the digital simulation. The analytical results are validated with the numerical results. The effect of substrate concentration, maximum enzymatic rate, and membrane thickness on biosensor response was evaluated. Full article

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12 pages, 7817 KiB

Open AccessArticle

Modification of Cu(111) Surface with Alkylphosphonic Acids in Aqueous and Ethanol Solution—An Experimental and Theoretical Study

by Valbonë Mehmeti and Fetah Podvorica

Electrochem 2022, 3(1), 58-69; https://doi.org/10.3390/electrochem3010004 - 16 Jan 2022

Cited by 1 | Viewed by 2904

Abstract

Alkylphosphonic acids are well known for their ability to form self-assembled monolayers on hydroxide surfaces. A crucial step to understanding fundamentally how these surfaces are created is the elucidation of the interaction process that leads to such interface creation. In this study, we [...] Read more.

Alkylphosphonic acids are well known for their ability to form self-assembled monolayers on hydroxide surfaces. A crucial step to understanding fundamentally how these surfaces are created is the elucidation of the interaction process that leads to such interface creation. In this study, we employed electrochemical impedance spectroscopy (EIS), Monte Carlo and molecular dynamics to understand this process. The interaction with the Cu(111) surface of three different alkylphosphonic acids (hexyl-, octyl- and decylphosphonic acids) is evaluated in an aqueous acidic and in an ethanol solution by Monte Carlo and molecular dynamics simulations, while EIS measurements are used to put in evidence the impact of the layer made in ethanol on copper protection. Nyquist diagrams of copper samples modified with an alkylphosphonic monolayer showed a higher polarization resistance that mitigates the copper corrosion in an aqueous acid medium. The phase–frequency Bode plots had higher and broader phase maxima for a modified copper surface with phosphonic moieties, which confirmed the ability of this organic layer to prevent copper corrosion. Full article

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16 pages, 3697 KiB

Open AccessArticle

Application of Machine Learning in Battery: State of Charge Estimation Using Feed Forward Neural Network for Sodium-Ion Battery

by Devendrasinh Darbar and Indranil Bhattacharya

Electrochem 2022, 3(1), 42-57; https://doi.org/10.3390/electrochem3010003 - 11 Jan 2022

Cited by 19 | Viewed by 4916

Abstract

Estimating the accurate State of Charge (SOC) of a battery is important to avoid the over/undercharging and protect the battery pack from low cycle life. Current methods of SOC estimation use complex equations in the Extended Kalman Filter (EKF) and the equivalent circuit [...] Read more.

Estimating the accurate State of Charge (SOC) of a battery is important to avoid the over/undercharging and protect the battery pack from low cycle life. Current methods of SOC estimation use complex equations in the Extended Kalman Filter (EKF) and the equivalent circuit model. In this paper, we used a Feed Forward Neural Network (FNN) to estimate the SOC value accurately where battery parameters such as current, voltage, and charge are mapped directly to the SOC value at the output. A FNN could self-learn the weights with each training data point and update the model parameters such as weights and bias using a combination of two gradient descents (Adam). This model comprises the Dropout technique, which can have many neural network architectures by dropping the neuron/mode at each epoch/training cycle using the same weights and biases. Our FNN model was trained with data comprising different current rates and tested for different cycling data, for example, 5th, 10th, 20th, and 50th cycles and at a different cutoff voltage (4.5 V). The battery used for estimating the SOC value was a Na-ion based battery, which is highly non-linear, and it was fabricated in a house using Na_0.67Fe_0.5Mn_0.5O₂ (NFM) as a cathode and Na metal as a reference electrode. The FNN successfully estimated the SOC value for the highly non-linear nature of the Na-ion battery at different current rates (0.05 C, 0.1 C, 0.5 C, 1 C, 2 C), for different cycling data, and at higher cut-off voltage of –4.5 V Na^+, reaching the R² value of ~0.97–~0.99, ~0.99, and ~0.98, respectively. Full article

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14 pages, 5423 KiB

Open AccessArticle

An Experimental and Theoretical Investigation of the Efficacy of Pantoprazole as a Corrosion Inhibitor for Mild Steel in an Acidic Medium

by Avni Berisha

Electrochem 2022, 3(1), 28-41; https://doi.org/10.3390/electrochem3010002 - 6 Jan 2022

Cited by 9 | Viewed by 3343

Abstract

The corrosion behavior of mild steel in a 1 M aqueous sulfuric acid medium in the presence and absence of the drug Pantoprazole was investigated using potentiodynamic polarization and quantum chemical calculations as well as Monte Carlo and molecular dynamic simulations. The potentiodynamic [...] Read more.

The corrosion behavior of mild steel in a 1 M aqueous sulfuric acid medium in the presence and absence of the drug Pantoprazole was investigated using potentiodynamic polarization and quantum chemical calculations as well as Monte Carlo and molecular dynamic simulations. The potentiodynamic experiments indicated that this molecule, as a result of its adsorption on a mild steel surface, functioned as a mixed inhibitor. The goal of the study was to use theoretical calculations to acquire a better understanding of how inhibition works. The adsorption behavior of the examined compounds on the Fe (1 1 0) surface was calculated using a Monte Carlo simulation. Furthermore, the molecules were studied using density functional theory (DFT), especially the PBE functional, to determine the relationship between the molecular structure and the corrosion inhibition behavior of the chemical under research. The adsorption energies of Pantoprazole (in its three different protonation states) iron were calculated more precisely using molecular mechanics with periodic boundary conditions (PBC). The predicted theoretical parameters were found to be in agreement with the experimental data, which was a considerable help in understanding the corrosion inhibition mechanism displayed by this chemical. Full article

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2021

Jump to: 2024, 2023, 2022

27 pages, 3111 KiB

Open AccessReview

Recent Advancements in the Synthesis and Application of Carbon-Based Catalysts in the ORR

by Samantha Macchi, Iris Denmark, Thuy Le, Mavis Forson, Mujeebat Bashiru, Amanda Jalihal and Noureen Siraj

Electrochem 2022, 3(1), 1-27; https://doi.org/10.3390/electrochem3010001 - 27 Dec 2021

Cited by 18 | Viewed by 5275

Abstract

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells [...] Read more.

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes. Full article

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13 pages, 2177 KiB

Open AccessReview

Recent Applications of Molecular Structures at Silicon Anode Interfaces

by Chen Fang and Gao Liu

Electrochem 2021, 2(4), 664-676; https://doi.org/10.3390/electrochem2040041 - 18 Dec 2021

Viewed by 3720

Abstract

Silicon (Si) is a promising anode material to realize many-fold higher anode capacity in next-generation lithium-ion batteries (LIBs). Si electrochemistry has strong dependence on the property of the Si interface, and therefore, Si surface engineering has attracted considerable research interest to address the [...] Read more.

Silicon (Si) is a promising anode material to realize many-fold higher anode capacity in next-generation lithium-ion batteries (LIBs). Si electrochemistry has strong dependence on the property of the Si interface, and therefore, Si surface engineering has attracted considerable research interest to address the challenges of Si electrodes such as dramatic volume changes and the high reactivity of Si surface. Molecular nanostructures, including metal–organic frameworks (MOFs), covalent–organic frameworks (COFs) and monolayers, have been employed in recent years to decorate or functionalize Si anode surfaces to improve their electrochemical performance. These materials have the advantages of facile preparation, nanoscale controllability and structural diversity, and thus could be utilized as versatile platforms for Si surface modification. This review aims to summarize the recent applications of MOFs, COFs and monolayers for Si anode development. The functionalities and common design strategies of these molecular structures are demonstrated. Full article

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21 pages, 8855 KiB

Open AccessArticle

Coupled Electrochemical-Thermal Simulations and Validation of Minichannel Cold-Plate Water-Cooled Prismatic 20 Ah LiFePO₄ Battery

by Chaithanya Akkaldevi, Sandeep Dattu Chitta, Jeevan Jaidi, Satyam Panchal, Michael Fowler and Roydon Fraser

Electrochem 2021, 2(4), 643-663; https://doi.org/10.3390/electrochem2040040 - 22 Nov 2021

Cited by 88 | Viewed by 5214

Abstract

This paper discusses the quantitative validation carried out on a prismatic 20 Ah LiFePO₄ battery sandwiched between two minichannel cold-plates with distributed flow having a single U-turn. A two-way coupled electrochemical-thermal simulations are performed at different discharge rates (1–4 C) and coolant [...] Read more.

This paper discusses the quantitative validation carried out on a prismatic 20 Ah LiFePO₄ battery sandwiched between two minichannel cold-plates with distributed flow having a single U-turn. A two-way coupled electrochemical-thermal simulations are performed at different discharge rates (1–4 C) and coolant inlet temperatures (15–35 °C). The predicted battery voltage response at room temperature (22 °C) and the performance of the Battery Thermal Management System (BTMS) in terms of the battery surface temperatures (maximum temperature,

T_{m a x}

and temperature difference,

Δ T

) have been analyzed. Additionally, temperature variation at ten different locations on the battery surface is studied during the discharge process. The predicted temperatures are compared with the measured data and found to be in close agreement. Differences between the predicted and measured temperatures are attributed to the assumption of uniform heat generation by the Li-ion model (P2D), the accuracy of electrochemical property input data, and the accuracy of the measuring tools used. Overall, it is suggested that the Li-ion model can be used to design the efficient BTMS at the cell level. Full article

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12 pages, 2474 KiB

Open AccessArticle

Double-Layer Capacitances Caused by Ion–Solvent Interaction in the Form of Langmuir-Typed Concentration Dependence

by Koichi Jeremiah Aoki, Ridong He and Jingyuan Chen

Electrochem 2021, 2(4), 631-642; https://doi.org/10.3390/electrochem2040039 - 18 Nov 2021

Cited by 3 | Viewed by 3042

Abstract

Variations of the double layer capacitances (DLCs) at a platinum electrode with concentrations and kinds of salts in aqueous solutions were examined in the context of facilitating orientation of solvent dipoles. With an increase in ionic concentrations, the DLCs increased by ca. a [...] Read more.

Variations of the double layer capacitances (DLCs) at a platinum electrode with concentrations and kinds of salts in aqueous solutions were examined in the context of facilitating orientation of solvent dipoles. With an increase in ionic concentrations, the DLCs increased by ca. a half and then kept constant at concentrations over 1 mol dm⁻³. This increase was classically explained in terms of the Gouy–Chapman (GC) equation combined with the Stern model. Unfortunately, measured DLCs were neither satisfied with the Stern model nor the GC theory. Our model suggests that salts destroy hydrogen bonds at the electrode–solution interface to orient water dipoles toward the external electric field. A degree of the orientation depends on the interaction energy between the salt ion and a water dipole. The statistical mechanic calculation allowed us to derive an equation for the DLC as a function of salt concentration and the interaction energy. The equation took the Langmuir-type in the relation with the concentration. The interaction energy was obtained for eight kinds of salts. The energy showed a linear relation with the interaction energy of ion–solvent for viscosity, called the B-coefficient. Full article

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14 pages, 6855 KiB

Open AccessReview

Catalysts for Oxygen Reduction Reaction in the Polymer Electrolyte Membrane Fuel Cells: A Brief Review

by Martin Tomas, Fatemeh Gholami, Zahra Gholami and Jan Sedlacek

Electrochem 2021, 2(4), 590-603; https://doi.org/10.3390/electrochem2040037 - 22 Oct 2021

Cited by 4 | Viewed by 4158

Abstract

This mini-review presents a short account of materials with exceptional activity towards oxygen reduction reaction. Two main classes of catalytic materials are described, namely platinum group metal (PGM) catalyst and Non-precious metal catalyst. The classes are discussed in terms of possible application in [...] Read more.

This mini-review presents a short account of materials with exceptional activity towards oxygen reduction reaction. Two main classes of catalytic materials are described, namely platinum group metal (PGM) catalyst and Non-precious metal catalyst. The classes are discussed in terms of possible application in low-temperature hydrogen fuel cells with proton exchange membrane and further commercialization of these devices. A short description of perspective approaches is provided and challenging issues associated with developed catalytic materials are discussed. Full article

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27 pages, 6941 KiB

Open AccessReview

Fabrication of Metal/Carbon Nanotube Composites by Electrochemical Deposition

by Susumu Arai

Electrochem 2021, 2(4), 563-589; https://doi.org/10.3390/electrochem2040036 - 21 Oct 2021

Cited by 11 | Viewed by 5360

Abstract

Metal/carbon nanotube (CNT) composites are promising functional materials due to the various superior properties of CNTs in addition to the characteristics of metals, and consequently, many fabrication processes of these composites have been vigorously researched. In this paper, the fabrication process of metal/CNT [...] Read more.

Metal/carbon nanotube (CNT) composites are promising functional materials due to the various superior properties of CNTs in addition to the characteristics of metals, and consequently, many fabrication processes of these composites have been vigorously researched. In this paper, the fabrication process of metal/CNT composites by electrochemical deposition, including electrodeposition and electroless deposition, are comprehensively reviewed. A general introduction for fabrication of metal/CNT composites using the electrochemical deposition is carried out. The fabrication methods can be classified into three types: (1) composite plating by electrodeposition or electroless deposition, (2) metal coating on CNT by electroless deposition, and (3) electrodeposition using CNT templates, such as CNT sheets and CNT yarns. The performances of each type have been compared and explained especially from the view point of preparation methods. In the cases of (1) composite plating and (2) metal coating on CNTs, homogeneous dispersion of CNTs in electrochemical deposition baths is essential for the formation of metal/CNT composites with homogeneous distribution of CNTs, which leads to high performance composites. In the case of (3) electrodeposition using CNT templates, the electrodeposition of metals not only on the surfaces but also interior of the CNT templates is the key process to fabricate high performance metal/CNT composites. Full article

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17 pages, 4943 KiB

Open AccessArticle

Effect of Cr Content on Corrosion Resistance of Low-Cr Alloy Steels Studied by Surface and Electrochemical Techniques

by Alicja Łukaszczyk, Jacek Banaś, Marcin Pisarek, Antoine Seyeux, Philippe Marcus and Jolanta Światowska

Electrochem 2021, 2(4), 546-562; https://doi.org/10.3390/electrochem2040035 - 18 Oct 2021

Cited by 8 | Viewed by 3522

Abstract

The electrochemical behavior of low alloyed Fe-Cr steels with 3 and 5% wt. of Cr in neutral Na₂SO₄ electrolyte combined with a detailed chemical and morphological characterization of these alloys performed by Auger electron spectroscopy, X-ray photoelectron spectroscopy, time-of-flight secondary [...] Read more.

The electrochemical behavior of low alloyed Fe-Cr steels with 3 and 5% wt. of Cr in neutral Na₂SO₄ electrolyte combined with a detailed chemical and morphological characterization of these alloys performed by Auger electron spectroscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry and scanning electron microscopy are presented here. The corrosion of low alloyed Fe-Cr steels proceeds in the prepassive range, with the formation of corrosion surface films having a duplex structure with outer iron oxide/hydroxide layer and inner Cr oxide-rich layer. The thickness, composition, and the morphology of the surface films vary as a function of chromium content in the alloy as well as conditions of electrochemical tests (temperature). Even a low chromium content shows a beneficial effect on the corrosion performances of the Fe-Cr steels. The chromium as a more active component than iron of ferrite increases the anodic activity of this phase, which results in a rapid saturation of the surface with the anodic reaction products forming a fine crystalline-like and compact layer of corrosion products. In this way, the chromium acts as a modifier of formation/crystallization of the iron-rich surface film (mainly magnetite) in the prepassive range. Full article

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12 pages, 9609 KiB

Open AccessArticle

Synthesis and Characterization of Supercapacitor Materials from Soy

by Iris Denmark, Amna Khan, Taylor Scifres, Tito Viswanathan, Fumiya Watanabe and Noureen Siraj

Electrochem 2021, 2(4), 534-545; https://doi.org/10.3390/electrochem2040034 - 14 Oct 2021

Cited by 4 | Viewed by 3407

Abstract

Renewable resources and their byproducts are becoming of growing interest for alternative energy. Here, we have demonstrated the use of Arkansas’ most important crop, soy, as a carbon precursor for the synthesis of carbonized activated materials for supercapacitor applications. Different soy products (soymeal, [...] Read more.

Renewable resources and their byproducts are becoming of growing interest for alternative energy. Here, we have demonstrated the use of Arkansas’ most important crop, soy, as a carbon precursor for the synthesis of carbonized activated materials for supercapacitor applications. Different soy products (soymeal, defatted soymeal, soy flour and soy protein isolate) were converted into carbonized carbon and co-doped with phosphorus and nitrogen simultaneously, using a facile and time-effective microwave synthesis method. Ammonium polyphosphate was used as a doping agent which also absorbs microwave radiation. The surface morphology of the resulting carbonized materials was characterized in detail using scanning electron microscopy. X-ray photoelectron spectroscopy was also performed, which revealed the presence of a heteroelemental composition, along with different functional groups at the surface of the carbonized materials. Raman spectroscopy results depicted the presence of both a graphitic and defect carbon peak, with defect ratios of over one. The electrochemical performance of the materials was recorded using cyclic voltammetry in various electrolytes including acids, bases and salts. Among all the other materials, soymeal exhibited the highest specific capacitance value of 127 F/g in acidic electrolytes. These economic materials can be further tuned by changing the doping elements and their mole ratios to attain exceptional surface characteristics with improved specific capacitance values, in order to boost the economy of Arkansas, USA. Full article

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15 pages, 8710 KiB

Open AccessArticle

Electrodeposition of Cu-Mn Films as Precursor Alloys for the Synthesis of Nanoporous Cu

by Ezer Castillo and Nikolay Dimitrov

Electrochem 2021, 2(3), 520-533; https://doi.org/10.3390/electrochem2030033 - 13 Sep 2021

Cited by 4 | Viewed by 3625

Abstract

Cu-Mn alloy films are electrodeposited on Au substrates as precursor alloys for the synthesis of fine-structured nanoporous Cu structures. The alloys are deposited galvanostatically in a solution containing ammonium sulfate, (NH₄)₂SO₄, which serves as a source of [...] Read more.

Cu-Mn alloy films are electrodeposited on Au substrates as precursor alloys for the synthesis of fine-structured nanoporous Cu structures. The alloys are deposited galvanostatically in a solution containing ammonium sulfate, (NH₄)₂SO₄, which serves as a source of the ammine ligand that complexes with Cu, thereby decreasing the inherent standard reduction potential difference between Cu and Mn. The formation of the [Cu(NH₃)_n]²⁺ complex was confirmed by UV-Vis spectroscopic and voltammetric studies. Galvanostatic deposition at current densities ranging from 100 to 200 mA⋅cm⁻² generally resulted in the formation of type I, crystalline coatings as revealed by scanning electron microscopy. Although the deposition current efficiency is (<30%) generally low, the atomic composition (determined by energy dispersive X-ray spectroscopy) of the deposited alloys range from 70–85 at% Mn, which is controlled by simply adjusting the ratio of the metal ion concentrations in the deposition bath. Anodic stripping characterization revealed a three-stage dissolution of the deposited alloys, which suggests control over the selective removal of Mn. The composition of the alloys obtained in the studies are ideal for electrochemical dealloying to form nanoporous Cu. Full article

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31 pages, 8393 KiB

Open AccessReview

Graphene Quantum Dots-Based Nanocomposites Applied in Electrochemical Sensors: A Recent Survey

by Murilo H. M. Facure, Rodrigo Schneider, Jessica B. S. Lima, Luiza A. Mercante and Daniel S. Correa

Electrochem 2021, 2(3), 490-519; https://doi.org/10.3390/electrochem2030032 - 6 Sep 2021

Cited by 40 | Viewed by 7619

Abstract

Graphene quantum dots (GQDs) have been widely investigated in recent years due to their outstanding physicochemical properties. Their remarkable characteristics allied to their capability of being easily synthesized and combined with other materials have allowed their use as electrochemical sensing platforms. In this [...] Read more.

Graphene quantum dots (GQDs) have been widely investigated in recent years due to their outstanding physicochemical properties. Their remarkable characteristics allied to their capability of being easily synthesized and combined with other materials have allowed their use as electrochemical sensing platforms. In this work, we survey recent applications of GQDs-based nanocomposites in electrochemical sensors and biosensors. Firstly, the main characteristics and synthesis methods of GQDs are addressed. Next, the strategies generally used to obtain the GQDs nanocomposites are discussed. Emphasis is given on the applications of GQDs combined with distinct 0D, 1D, 2D nanomaterials, metal-organic frameworks (MOFs), molecularly imprinted polymers (MIPs), ionic liquids, as well as other types of materials, in varied electrochemical sensors and biosensors for detecting analytes of environmental, medical, and agricultural interest. We also discuss the current trends and challenges towards real applications of GQDs in electrochemical sensors. Full article

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18 pages, 6596 KiB

Open AccessArticle

Light in Electrochemistry

by Hiroya Abe, Tomoki Iwama and Yuanyuan Guo

Electrochem 2021, 2(3), 472-489; https://doi.org/10.3390/electrochem2030031 - 26 Aug 2021

Cited by 6 | Viewed by 4317

Abstract

Electrochemistry represents an important analytical technique used to acquire and assess chemical information in detail, which can aid fundamental investigations in various fields, such as biological studies. For example, electrochemistry can be used as simple and cost-effective means for bio-marker tracing in applications, [...] Read more.

Electrochemistry represents an important analytical technique used to acquire and assess chemical information in detail, which can aid fundamental investigations in various fields, such as biological studies. For example, electrochemistry can be used as simple and cost-effective means for bio-marker tracing in applications, such as health monitoring and food security screening. In combination with light, powerful spatially-resolved applications in both the investigation and manipulation of biochemical reactions begin to unfold. In this article, we focus primarily on light-addressable electrochemistry based on semiconductor materials and light-readable electrochemistry enabled by electrochemiluminescence (ECL). In addition, the emergence of multiplexed and imaging applications will also be introduced. Full article

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20 pages, 6968 KiB

Open AccessReview

Review on Interface and Interphase Issues in Sulfide Solid-State Electrolytes for All-Solid-State Li-Metal Batteries

by Young-Woon Byeon and Haegyeom Kim

Electrochem 2021, 2(3), 452-471; https://doi.org/10.3390/electrochem2030030 - 2 Aug 2021

Cited by 42 | Viewed by 10819

Abstract

All-solid-state batteries have emerged as promising alternatives to conventional Li-ion batteries owing to their higher energy density and safety, which stem from their use of inorganic solid-state electrolytes instead of flammable organic liquid electrolytes. Among various candidates, sulfide solid-state electrolytes are particularly promising [...] Read more.

All-solid-state batteries have emerged as promising alternatives to conventional Li-ion batteries owing to their higher energy density and safety, which stem from their use of inorganic solid-state electrolytes instead of flammable organic liquid electrolytes. Among various candidates, sulfide solid-state electrolytes are particularly promising for the development of high-energy all-solid-state Li metal batteries because of their high ionic conductivity and deformability. However, a significant challenge remains as their inherent instability in contact with electrodes forms unstable interfaces and interphases, leading to degradation of the battery performance. In this review article, we provide an overview of the key issues for the interfaces and interphases of sulfide solid-state electrolyte systems as well as recent progress in understanding such interface and interphase formation and potential solutions to stabilize them. In addition, we provide perspectives on future research directions in this field. Full article

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13 pages, 19717 KiB

Open AccessArticle

Synthesis of Nickel Fumarate and Its Electrochemical Properties for Li-Ion Batteries

by Shahul A. Hameed, Shaikshavali Petnikota, Nusyba S. Hassan, Siham Y. Al-Qaradawi, Zaghib Karim and M. V. Reddy

Electrochem 2021, 2(3), 439-451; https://doi.org/10.3390/electrochem2030029 - 27 Jul 2021

Cited by 4 | Viewed by 3790

Abstract

Metal–organic frameworks (MOFs) have found a potential application in various domains such as gas storage/separation, drug delivery, catalysis, etc. Recently, they have found considerable attention for energy storage applications such as Li- and Na-ion batteries. However, the development of MOFs is plagued by [...] Read more.

Metal–organic frameworks (MOFs) have found a potential application in various domains such as gas storage/separation, drug delivery, catalysis, etc. Recently, they have found considerable attention for energy storage applications such as Li- and Na-ion batteries. However, the development of MOFs is plagued by their limited energy density that arises from high molecular weight and low volumetric density. The choice of ligand plays a crucial role in determining the performance of the MOFs. Here, we report a nickel-based one-dimensional metal-organic framework, NiC₄H₂O₄, built from bidentate fumarate ligands for anode application in Li-ion batteries. The material was obtained by a simple chimie douce precipitation method using nickel acetate and fumaric acid. Moreover, a composite material of the MOF with reduced graphene oxide (rGO) was prepared to enhance the lithium storage performance as the rGO can enhance the electronic conductivity. Electrochemical lithium storage in the framework and the effect of rGO on the performance have been investigated by cyclic voltammetry, galvanostatic charge–discharge measurements, and EIS studies. The pristine nickel formate encounters serious capacity fading while the rGO composite offers good cycling stability with high reversible capacities of over 800 mAh g⁻¹. Full article

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12 pages, 2479 KiB

Open AccessArticle

A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications

by Tânia S. C. R. Rebelo, Inês M. Miranda, Ana T. S. C. Brandão, Laura I. G. Sousa, José A. Ribeiro, António F. Silva and Carlos M. Pereira

Electrochem 2021, 2(3), 427-438; https://doi.org/10.3390/electrochem2030028 - 26 Jul 2021

Cited by 29 | Viewed by 6055

Abstract

The design and synthesis of artificial receptors based on molecular imprinting (MI) technology for the development of a new MIP-based biosensor for detection of the stress biomarker α-amylase in human saliva in point-of-care (PoC) applications is described in this work. The portable electrochemical [...] Read more.

The design and synthesis of artificial receptors based on molecular imprinting (MI) technology for the development of a new MIP-based biosensor for detection of the stress biomarker α-amylase in human saliva in point-of-care (PoC) applications is described in this work. The portable electrochemical devices for monitoring α-amylase consists of cost-effective and disposable gold screen-printed electrodes (AuSPEs). To build the electrochemical device, the template biomolecule was firstly immobilized directly over the working area of the gold chip previously activated with a self-assembled monolayer (SAM) of cysteamine (CA). Then, pyrrole (Py) monomer was selected as building block of a polymeric network prepared by CV electropolymerization. After the electropolymerization process, the enzyme was removed from the polymer film in order to build the specific recognition sites for the target enzyme. The MIP biosensor showed a very wide linear concentration range (between 3.0 × 10⁻⁴ to 0.60 mg mL⁻¹ in buffer solution and between 3.0 × 10⁻⁴ to 3.0 × 10⁻² mg mL⁻¹ in human saliva) and low detection levels were achieved (LOD < 3.0 × 10⁻⁴ mg mL⁻¹) using square wave voltammetry (SWV) as the electroanalytical technique. Full article

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12 pages, 17466 KiB

Open AccessArticle

Reduction of Cd(II) Ions in the Presence of Tetraethylammonium Cations. Adsorption Effect on the Electrode Process

by Juan Torrent-Burgués

Electrochem 2021, 2(3), 415-426; https://doi.org/10.3390/electrochem2030027 - 23 Jul 2021

Viewed by 2902

Abstract

The effect of the adsorption of tetraethylammonium (TEA) cations, which present both ionic and organic characteristics, on the reduction of Cd(II) ions have been studied from dc and ac measurements at the dropping mercury electrode. The resistance to the charge transfer (Rct) and [...] Read more.

The effect of the adsorption of tetraethylammonium (TEA) cations, which present both ionic and organic characteristics, on the reduction of Cd(II) ions have been studied from dc and ac measurements at the dropping mercury electrode. The resistance to the charge transfer (Rct) and Warburg coefficient (σ) parameters have been determined through impedance measurements. Thus, the global velocity constant has been obtained. The reduction process of Cd(II) in perchloric media is reversible and is affected by the adsorption of TEA cations, especially at high TEA concentrations. Values of E_1/2, half wave potential, and D_O, diffusion coefficient, obtained from both dc and ac measurements agree. The velocity constants show a decrease as TEA concentration increases, with values ranging from 0.6 to 0.01 cm·s⁻¹. The inhibitory effect of TEA adsorption on the electrode process and the relationship between electrode coverage, θ, and velocity constants, K, using several isotherm equations, have been discussed. The best fit was obtained with the equation K = ₀K(1 − θ)^a with an a value close to three, indicating a blocking effect and electrostatic repulsion due to TEA. Full article

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25 pages, 4655 KiB

Open AccessReview

Crystal Structure and Preparation of Li₇La₃Zr₂O₁₂ (LLZO) Solid-State Electrolyte and Doping Impacts on the Conductivity: An Overview

by Md Mozammal Raju, Fadhilah Altayran, Michael Johnson, Danling Wang and Qifeng Zhang

Electrochem 2021, 2(3), 390-414; https://doi.org/10.3390/electrochem2030026 - 19 Jul 2021

Cited by 54 | Viewed by 25012

Abstract

As an essential part of solid-state lithium-ion batteries, solid electrolytes are receiving increasing interest. Among all solid electrolytes, garnet-type Li₇La₃Zr₂O₁₂ (LLZO) has proven to be one of the most promising electrolytes because of its high ionic [...] Read more.

As an essential part of solid-state lithium-ion batteries, solid electrolytes are receiving increasing interest. Among all solid electrolytes, garnet-type Li₇La₃Zr₂O₁₂ (LLZO) has proven to be one of the most promising electrolytes because of its high ionic conductivity at room temperature, low activation energy, good chemical and electrochemical stability, and wide potential window. Since the first report of LLZO, extensive research has been done in both experimental investigations and theoretical simulations aiming to improve its performance and make LLZO a feasible solid electrolyte. These include developing different methods for the synthesis of LLZO, using different crucibles and different sintering temperatures to stabilize the crystal structure, and adopting different methods of cation doping to achieve more stable LLZO with a higher ionic conductivity and lower activation energy. It also includes intensive efforts made to reveal the mechanism of Li ion movement and understand its determination of the ionic conductivity of the material through molecular dynamic simulations. Nonetheless, more insightful study is expected in order to obtain LLZO with a higher ionic conductivity at room temperature and further improve chemical and electrochemical stability, while optimal multiple doping is thought to be a feasible and promising route. This review summarizes recent progress in the investigations of crystal structure and preparation of LLZO, and the impacts of doping on the lithium ionic conductivity of LLZO. Full article

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43 pages, 9695 KiB

Open AccessReview

Developments of the Electroactive Materials for Non-Enzymatic Glucose Sensing and Their Mechanisms

by Wan-Ting Chiu, Tso-Fu Mark Chang, Masato Sone, Hideki Hosoda, Agnès Tixier-Mita and Hiroshi Toshiyoshi

Electrochem 2021, 2(2), 347-389; https://doi.org/10.3390/electrochem2020025 - 21 Jun 2021

Cited by 10 | Viewed by 5034

Abstract

A comprehensive review of the electroactive materials for non-enzymatic glucose sensing and sensing devices has been performed in this work. A general introduction for glucose sensing, a facile electrochemical technique for glucose detection, and explanations of fundamental mechanisms for the electro-oxidation of glucose [...] Read more.

A comprehensive review of the electroactive materials for non-enzymatic glucose sensing and sensing devices has been performed in this work. A general introduction for glucose sensing, a facile electrochemical technique for glucose detection, and explanations of fundamental mechanisms for the electro-oxidation of glucose via the electrochemical technique are conducted. The glucose sensing materials are classified into five major systems: (1) mono-metallic materials, (2) bi-metallic materials, (3) metallic-oxide compounds, (4) metallic-hydroxide materials, and (5) metal-metal derivatives. The performances of various systems within this decade have been compared and explained in terms of sensitivity, linear regime, the limit of detection (LOD), and detection potentials. Some promising materials and practicable methodologies for the further developments of glucose sensors have been proposed. Firstly, the atomic deposition of alloys is expected to enhance the selectivity, which is considered to be lacking in non-enzymatic glucose sensing. Secondly, by using the modification of the hydrophilicity of the metallic-oxides, a promoted current response from the electro-oxidation of glucose is expected. Lastly, by taking the advantage of the redistribution phenomenon of the oxide particles, the usage of the noble metals is foreseen to be reduced. Full article

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12 pages, 3085 KiB

Open AccessArticle

Synergistic Effect of Polymorphs in Doped NaNi_0.5Mn_0.5O₂ Cathode Material for Improving Electrochemical Performances in Na-Batteries

by Francesco Leccardi, Davide Nodari, Daniele Spada, Marco Ambrosetti and Marcella Bini

Electrochem 2021, 2(2), 335-346; https://doi.org/10.3390/electrochem2020024 - 4 Jun 2021

Cited by 7 | Viewed by 3942

Abstract

Layered NaNi_0.5Mn_0.5O₂, employed as cathode materials in sodium ion batteries, is attracting interest due to its high working potential and high-capacity values, thanks to the big sodium amount hosted in the lattice. Many issues are, however, related [...] Read more.

Layered NaNi_0.5Mn_0.5O₂, employed as cathode materials in sodium ion batteries, is attracting interest due to its high working potential and high-capacity values, thanks to the big sodium amount hosted in the lattice. Many issues are, however, related to their use, particularly, the complex phase transitions occurring during sodium intercalation/deintercalation, detrimental for the structure stability, and the possible Mn dissolution into the electrolyte. In this paper, the doping with Ti, V, and Cu ions (10% atoms with respect to Ni/Mn amount) was used to stabilize different polymorphs or mixtures of them with the aim to improve the capacity values and cells cyclability. The phases were identified and quantified by means of X-ray powder diffraction with Rietveld structural refinements. Complex voltammograms with broad peaks, due to multiple structural transitions, were disclosed for most of the samples. Ti-doped sample has, in general, the best performances with the highest capacity values (120 mAh/g at C/10), however, at higher currents (1C), Cu-substituted sample also has stable and comparable capacity values. Full article

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12 pages, 4355 KiB

Open AccessArticle

Understanding the Effect of Zn Doping on Stability of Cobalt-Free P2-Na_0.60Fe_0.5Mn_0.5O₂ Cathode for Sodium Ion Batteries

by Devendrasinh Darbar, M. V. Reddy and Indranil Bhattacharya

Electrochem 2021, 2(2), 323-334; https://doi.org/10.3390/electrochem2020023 - 2 Jun 2021

Cited by 8 | Viewed by 5219

Abstract

In this work, we report a sol-gel synthesis-based Zn-doped Na_0.6Fe_0.5Mn_0.5O₂ (NFM) cathode and understand the effect of Zn doping on the crystal structure and electrochemical performances such as discharge capacity and rate capability. Detailed X-Ray diffraction [...] Read more.

In this work, we report a sol-gel synthesis-based Zn-doped Na_0.6Fe_0.5Mn_0.5O₂ (NFM) cathode and understand the effect of Zn doping on the crystal structure and electrochemical performances such as discharge capacity and rate capability. Detailed X-Ray diffraction (XRD) pattern analysis indicated a decrease in the Na-layer thickness with Zn doping. Small amount of Zn²⁺ dopant (i.e., 2 at.%) slightly improved cycling stability, reversibility, and rate performances at higher discharge current rates. For example, at 1 C-rate (1 C = 260 mAh/g), the Zn²⁺-doped cathode retained a stable reversible capacity of 72 mAh/g, which was ~16% greater than that of NFM (62 mAh/g) and showed a minor improvement in the capacity retention of 60% compared to 55% for the pristine NFM after 65 cycles. Slight improvement in the electrochemical performance for the Zn-doped cathode can be attributed to a better structural stability, which prevented the initial phase transition and showed the presence of electrochemical active Fe^3+/4+ even after 10 cycles compared to NFM. Full article

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12 pages, 2861 KiB

Open AccessArticle

Characterization and Electrocatalytic Performance of Molasses Derived Co-Doped (P, N) and Tri-Doped (Si, P, N) Carbon for the ORR

by Samantha Macchi, Fumiya Watanabe, Tito Viswanathan and Noureen Siraj

Electrochem 2021, 2(2), 311-322; https://doi.org/10.3390/electrochem2020022 - 2 Jun 2021

Cited by 4 | Viewed by 4136

Abstract

There is a growing need to develop sustainable electrocatalysts to facilitate the reduction of molecular oxygen that occurs at the cathode in fuel cells, due to the excessive cost and limited availability of precious metal-based catalysts. This study reports the synthesis and characterization [...] Read more.

There is a growing need to develop sustainable electrocatalysts to facilitate the reduction of molecular oxygen that occurs at the cathode in fuel cells, due to the excessive cost and limited availability of precious metal-based catalysts. This study reports the synthesis and characterization of phosphorus and nitrogen co-doped carbon (PNDC) and silicon, phosphorus, and nitrogen tri-doped carbon (SiPNDC) electrocatalysts derived from molasses. This robust microwave-assisted synthesis approach is used to develop a low cost and environmentally friendly carbon with high surface area for application in fuel cells. Co-doped PNDC as well as tri-doped SiPNDC showed Brunauer–Emmet–Teller (BET) surface areas of 437 and 426 m² g⁻¹, respectively, with well-developed porosity. However, examination of X-ray photoelectron spectroscopy (XPS) data revealed significant alteration in the doping elemental composition among both samples. The results obtained using rotating disk electrode (RDE) measurements show that tri-doped SiPNDC achieves much closer to a 4-electron process than co-doped PNDC. Detailed analysis of experimental results acquired from rotating ring disk electrode (RRDE) studies indicates that there is a negligible amount of peroxide formation during ORR, further confirming the direct-electron transfer pathway results obtained from RDE. Furthermore, SiPNDC shows stable oxygen reduction reaction (ORR) performance over 2500 cycles, making this material a promising electrocatalyst for fuel cell applications. Full article

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16 pages, 4250 KiB

Open AccessArticle

Efficient Electrocatalytic Approach to Spiro[Furo[3,2-b]pyran-2,5′-pyrimidine] Scaffold as Inhibitor of Aldose Reductase

by Michail N. Elinson, Anatoly N. Vereshchagin, Yuliya E. Ryzhkova, Fedor V. Ryzhkov, Artem N. Fakhrutdinov and Mikhail P. Egorov

Electrochem 2021, 2(2), 295-310; https://doi.org/10.3390/electrochem2020021 - 25 May 2021

Viewed by 3900

Abstract

A continuously growing interest in convenient and ‘green’ reaction techniques encourages organic chemists to elaborate on new synthetic methodologies. Nowadays, organic electrochemistry is a new useful method with important synthetic and ecological advantages. The employment of an electrocatalytic methodology in cascade reactions is [...] Read more.

A continuously growing interest in convenient and ‘green’ reaction techniques encourages organic chemists to elaborate on new synthetic methodologies. Nowadays, organic electrochemistry is a new useful method with important synthetic and ecological advantages. The employment of an electrocatalytic methodology in cascade reactions is very promising because it provides the combination of the synthetic virtues of the cascade strategy with the ecological benefits and convenience of electrocatalytic procedures. In this research, a new type of the electrocatalytic cascade transformation was found: the electrochemical cyclization of 1,3-dimethyl-5-[[3-hydroxy-6-(hydroxymethyl)-4-oxo-4H-pyran-2-yl](aryl)methyl]pyrimidine-2,4,6(1H,3H,5H)-triones was carried out in alcohols in an undivided cell in the presence of sodium halides with the selective formation of spiro[furo[3,2-b]pyran-2,5′-pyrimidines] in 59-95% yields. This new electrocatalytic process is a selective, facile, and efficient way to create spiro[furo[3,2-b]pyran-2,5′-pyrimidines], which are pharmacologically active heterocyclic systems with different biomedical applications. Spiro[furo[3,2-b]pyran-2,5′-pyrimidines] were found to occupy the binding pocket of aldose reductase and inhibit it. The values of the binding energy and Lead Finder’s Virtual Screening scoring function showed that the formation of protein–ligand complexes was favorable. The synthesized compounds are promising for the inhibition of aldose reductase. This makes them interesting for study in the treatment of diabetes or similar diseases. Full article

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21 pages, 4021 KiB

Open AccessReview

A Short Review on Electrochemical Sensing of Commercial Dyes in Real Samples Using Carbon Paste Electrodes

by Isha Soni, Pankaj Kumar, Shruti Sharma and Gururaj Kudur Jayaprakash

Electrochem 2021, 2(2), 274-294; https://doi.org/10.3390/electrochem2020020 - 25 May 2021

Cited by 30 | Viewed by 5558

Abstract

Synthetic dyes are commonly used in food products like soft drinks, vegetable sauces, jellies, etc. Most artificial dyes can cause cancer, therefore it is very important to develop sensors to detect them in food samples. Voltammetric methods with carbon paste electrodes (CPEs) are [...] Read more.

Synthetic dyes are commonly used in food products like soft drinks, vegetable sauces, jellies, etc. Most artificial dyes can cause cancer, therefore it is very important to develop sensors to detect them in food samples. Voltammetric methods with carbon paste electrodes (CPEs) are promising for this purpose. However, modification of CPEs is necessary to detect the commercial dyes in food samples in the presence of interferents. In the current review, we have discussed the different previous research in which detection of dyes is performed in real samples with good detection limits. The current review will be helpful for readers who are interested in developing low-cost electrodes for the effective determination of dyes in commercial products like soft drinks and vegetable sauces. Full article

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10 pages, 2157 KiB

Open AccessArticle

Solid-State Electrochemical Energy Storage Based on Soluble Melanin

by João V. Paulin, Silvia L. Fernandes and Carlos F. O. Graeff

Electrochem 2021, 2(2), 264-273; https://doi.org/10.3390/electrochem2020019 - 25 May 2021

Cited by 19 | Viewed by 3394

Abstract

Biocompatible and biodegradable powering materials are appealing systems for biomedical and electronic devices. Melanin is a natural and multifunctional material with redox capability, which is of great interest in electrochemical energy storage functionalities. In our work, we explored the use of soluble melanin [...] Read more.

Biocompatible and biodegradable powering materials are appealing systems for biomedical and electronic devices. Melanin is a natural and multifunctional material with redox capability, which is of great interest in electrochemical energy storage functionalities. In our work, we explored the use of soluble melanin derivatives as active materials for symmetric solid-state supercapacitors operating in the dark and under illumination. We observed that our devices were photo-pseudocapacitive. Additionally, under illumination, our best device showed a specific capacitance of 57.7 mFg⁻¹ at a scan rate of 0.01 Vs⁻¹, with a decrease of 53% in resistance compared to that in the dark. Our outcome suggests that soluble melanin is a promising material for solid-state powering elements in wearable and environmentally friendly devices. Full article

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13 pages, 3317 KiB

Open AccessArticle

Development of an Electrochemical Sensor Based on Nanocomposite of Fe₃O₄@SiO₂ and Multiwalled Carbon Nanotubes for Determination of Tetracycline in Real Samples

by Edna Ferreira Amaral, Daniela Nunes da Silva, Maria Cristina Silva and Arnaldo César Pereira

Electrochem 2021, 2(2), 251-263; https://doi.org/10.3390/electrochem2020018 - 18 May 2021

Cited by 10 | Viewed by 3341

Abstract

In this work, an electrochemical sensor (GCE/MWCNT/Fe₃O₄@SiO₂) based on a composite of multiwalled carbon nanotubes (MWCNT) and an Fe₃O₄@SiO₂ (MMN) nanocomposite on a glassy carbon electrode (GCE) was developed for the detection [...] Read more.

In this work, an electrochemical sensor (GCE/MWCNT/Fe₃O₄@SiO₂) based on a composite of multiwalled carbon nanotubes (MWCNT) and an Fe₃O₄@SiO₂ (MMN) nanocomposite on a glassy carbon electrode (GCE) was developed for the detection of tetracycline (TC). The composite formed promoted an increased electrochemical signal and the stability of the sensor, combining its individual characteristics such as high electrical conductivity and large surface area. The composite material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Mössbauer spectroscopy, and scanning electron microscope (SEM). The adsorptive stripping differential pulse voltammetry (AdSDPV) promoted better performance for the electrochemical sensor and greater sensitivity for TC detection. Under optimized conditions, the currents increased linearly with TC concentrations from 4.0 to 36 µmol L⁻¹ (0.997) and from 40 to 64 µmol L⁻¹ (0.994) with detection and quantification limits of 1.67 µmol L⁻¹ and 4.0 µmol L⁻¹, respectively. The sensor was applied in the analysis of milk and river water samples, obtaining recovery values ranging from 91–117%. Full article

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12 pages, 1339 KiB

Open AccessArticle

Electrolytic Reduction of Titanium Dioxide in Molten LiCl–Li₂O

by Meng Shi, Bin Liu, Shelly Li and Haiyan Zhao

Electrochem 2021, 2(2), 224-235; https://doi.org/10.3390/electrochem2020016 - 27 Apr 2021

Cited by 3 | Viewed by 3392

Abstract

The electrolytic reduction of TiO₂ in LiCl–Li₂O (1 wt.%) at 650 °C was investigated under a series of cathodic reduction potentials and applied charges to provide a mechanistic understanding of the electrochemical characteristics of the system. The optimal cathodic reduction [...] Read more.

The electrolytic reduction of TiO₂ in LiCl–Li₂O (1 wt.%) at 650 °C was investigated under a series of cathodic reduction potentials and applied charges to provide a mechanistic understanding of the electrochemical characteristics of the system. The optimal cathodic reduction potential was determined as being −0.3 V vs. Li/Li⁺. Li₂TiO₃ and LiTiO₂ were structurally identified as intermediate and partial reduction products of the TiO₂ electrolytic reduction. The reduction of LiTiO₂ was extremely slow and reversible due to its high stability and the detrimental effect of Li₂O accumulation within the solid particles. The most reduced product obtained in this study was LiTiO₂, which was achieved when using 150% of the theoretical charge under the optimal reduction potential. The highest reduction extent obtained in this study was 25%. Based on theoretical DFT modeling, a detailed multistep reduction mechanism and scheme were proposed for TiO₂ electrolytic reduction in LiCl–Li₂O (1 wt.%) at 650 °C. Full article

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12 pages, 2843 KiB

Open AccessArticle

Electrodeposition of Aluminum in the 1-Ethyl-3-Methylimidazolium Tetrachloroaluminate Ionic Liquid

by Meng Shi, Junhua Jiang and Haiyan Zhao

Electrochem 2021, 2(2), 185-196; https://doi.org/10.3390/electrochem2020013 - 26 Mar 2021

Cited by 6 | Viewed by 4657

Abstract

The electrodeposition of Al was investigated in an ionic liquid (IL), with 1-ethyl-3-methylimidazolium tetrachloroaluminate ([EMIm]AlCl₄) as the electrolyte with AlCl₃ precursor. The [EMIm]AlCl₄ electrolyte exhibited a wide and stable electrochemical window from 3.2 to 2.3 V on a glassy [...] Read more.

The electrodeposition of Al was investigated in an ionic liquid (IL), with 1-ethyl-3-methylimidazolium tetrachloroaluminate ([EMIm]AlCl₄) as the electrolyte with AlCl₃ precursor. The [EMIm]AlCl₄ electrolyte exhibited a wide and stable electrochemical window from 3.2 to 2.3 V on a glassy carbon electrode when temperature was increased from 30 °C to 110 °C. The addition of AlCl₃ into [EMIm]AlCl₄ generated significant well-developed nucleation growth loops, and new coupled reduction and oxidation peaks in cyclic voltammograms corresponding to the Al deposition and dissolution, respectively. A calculation model was proposed predicting compositions of anions in AlCl₃/[EMIm]AlCl₄ system, and [Al₂Cl₇]⁻ was found to be the active species for Al deposition. In AlCl₃/[EMIm]AlCl₄ (1:5), the reduction rate constants were 1.18 × 10⁻⁵ cm s⁻¹ and 3.37 × 10⁻⁴ cm s⁻¹ at 30 °C and 110 °C, respectively. Scanning electron microscope (SEM), energy dispersive spectroscope (EDS), and X-ray diffraction (XRD) microscope results showed that the metallic Al film had been successfully deposited on glassy carbon electrodes through constant-potential cathodic reductions. The [EMIm]AlCl₄ was a promising electrolyte directly used for Al deposition. Full article

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14 pages, 2727 KiB

Open AccessArticle

Investigation of the Applicability of Helium-Based Cooling System for Li-Ion Batteries

by Mohammad Alipour, Aliakbar Hassanpouryouzband and Riza Kizilel

Electrochem 2021, 2(1), 135-148; https://doi.org/10.3390/electrochem2010011 - 8 Mar 2021

Cited by 8 | Viewed by 4202

Abstract

This paper proposes a novel He-based cooling system for the Li-ion batteries (LIBs) used in electric vehicles (EVs) and hybrid electric vehicles (HEVs). The proposed system offers a novel alternative battery thermal management system with promising properties in terms of safety, simplicity, and [...] Read more.

This paper proposes a novel He-based cooling system for the Li-ion batteries (LIBs) used in electric vehicles (EVs) and hybrid electric vehicles (HEVs). The proposed system offers a novel alternative battery thermal management system with promising properties in terms of safety, simplicity, and efficiency. A 3D multilayer coupled electrochemical-thermal model is used to simulate the thermal behavior of the 20 Ah LiFePO₄ (LFP) cells. Based on the results, He gas, compared to air, effectively diminishes the maximum temperature rise and temperature gradient on the cell surface and offers a viable option for the thermal management of Li-ion batteries. For instance, in comparison with air, He gas offers 1.18 and 2.29 °C better cooling at flow rates of 2.5 and 7.5 L/min, respectively. The cooling design is optimized in terms of the battery’s temperature uniformity and the battery’s maximum temperature. In this regard, the effects of various parameters such as inlet diameter, flow direction, and inlet flow rate are investigated. The inlet flow rate has a more evident influence on the cooling efficiency than inlet/outlet diameter and flow direction. The possibility of using helium as a cooling fluid is shown to open new doors in the subject matter of an effective battery thermal management system. Full article

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17 pages, 1041 KiB

Open AccessReview

Wearable Nanogenerators: Working Principle and Self-Powered Biosensors Applications

by Helinando Pequeno de Oliveira

Electrochem 2021, 2(1), 118-134; https://doi.org/10.3390/electrochem2010010 - 28 Feb 2021

Cited by 4 | Viewed by 4359

Abstract

Wearable self-powered sensors represent a theme of interest in the literature due to the progress in the Internet of Things and implantable devices. The integration of different materials to harvest energy from body movement or the environment to power up sensors or act [...] Read more.

Wearable self-powered sensors represent a theme of interest in the literature due to the progress in the Internet of Things and implantable devices. The integration of different materials to harvest energy from body movement or the environment to power up sensors or act as an active component of the detection of analytes is a frontier to be explored. This review describes the most relevant studies of the integration of nanogenerators in wearables based on the interaction of piezoelectric and triboelectric devices into more efficient and low-cost harvesting systems to power up batteries or to use the generated power to identify multiple analytes in self-powered sensors and biosensors. Full article

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