Topical Collection "Feature Papers in Electrochemistry"

Editor

Prof. Dr. Masato Sone
E-Mail Website
Guest Editor
Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
Interests: electrodeposition; electrochemistry; nanomaterials; metallurgy; sensor technology
Special Issues, Collections and Topics in MDPI journals

Topical Collection Information

Dear Colleagues,

As the Editor-in-Chief of Electrochem, I am pleased to announce this Collection titled “Feature Papers in Electrochemistry”. This topic will be a collection of high-quality papers from editorial board members, guest editors, and leading researchers invited by the editorial office and the Editor-in-Chief. Both original research articles and comprehensive review papers are welcome. The papers will be published with full open access after peer review.

Prof. Dr. Masato Sone
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the collection website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Keywords

  • electrochemical sensor
  • electrochemical device
  • electrochemical analysis
  • single-molecule detection
  • single-atom detection
  • molecular level monitoring
  • bio-electrochemistry

Published Papers (44 papers)

2022

Jump to: 2021

Article
Modelling the Current Response and Sensitivity of Oxidase Enzyme Electrodes, Monitored Amperometrically by the Consumption of Oxygen
Electrochem 2022, 3(2), 309-321; https://doi.org/10.3390/electrochem3020021 - 02 Jun 2022
Viewed by 274
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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Communication
Efficacy of the PlasmaShield®, a Non-Thermal, Plasma-Based Air Purification Device, in Removing Airborne Microorganisms
Electrochem 2022, 3(2), 276-284; https://doi.org/10.3390/electrochem3020019 - 01 Jun 2022
Viewed by 443
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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Article
Performance Study on the Effect of Coolant Inlet Conditions for a 20 Ah LiFePO4 Prismatic Battery with Commercial Mini Channel Cold Plates
Electrochem 2022, 3(2), 259-275; https://doi.org/10.3390/electrochem3020018 - 25 May 2022
Viewed by 354
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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Review
Electrochemical Reduction and Voltammetric Sensing of Lindane at the Carbon (Glassy and Pencil) Electrodes
Electrochem 2022, 3(2), 248-258; https://doi.org/10.3390/electrochem3020017 - 13 May 2022
Viewed by 486
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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Article
Chitosan/Gold Nanoparticles Nanocomposite Film for Bisphenol A Electrochemical Sensing
Electrochem 2022, 3(2), 239-247; https://doi.org/10.3390/electrochem3020016 - 04 May 2022
Viewed by 461
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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Article
N-Graphene Sheet Stacks/Cu Electrocatalyst for CO2 Reduction to Ethylene
Electrochem 2022, 3(2), 229-238; https://doi.org/10.3390/electrochem3020015 - 01 May 2022
Viewed by 579
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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Article
Alkaloid of Rhynchostylis retusa as Green Inhibitor for Mild Steel Corrosion in 1 M H2SO4 Solution
Electrochem 2022, 3(2), 211-224; https://doi.org/10.3390/electrochem3020013 - 18 Apr 2022
Cited by 1 | Viewed by 524
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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Article
Electrodeposition and Micro-Mechanical Property Characterization of Nickel–Cobalt Alloys toward Design of MEMS Components
Electrochem 2022, 3(2), 198-210; https://doi.org/10.3390/electrochem3020012 - 13 Apr 2022
Viewed by 450
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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Article
Ferrocene-Based Porous Organic Polymer (FPOP): Synthesis, Characterization and an Electrochemical Study
Electrochem 2022, 3(1), 184-197; https://doi.org/10.3390/electrochem3010011 - 27 Feb 2022
Viewed by 898
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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Review
Graphene: Chemistry and Applications for Lithium-Ion Batteries
Electrochem 2022, 3(1), 143-183; https://doi.org/10.3390/electrochem3010010 - 25 Feb 2022
Cited by 1 | Viewed by 1383
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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Article
Hydrogen Bond Donors Influence on the Electrochemical Performance of Composite Graphene Electrodes/Deep Eutectic Solvents Interface
Electrochem 2022, 3(1), 129-142; https://doi.org/10.3390/electrochem3010009 - 10 Feb 2022
Viewed by 857
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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Review
A Comprehensive Review on the Use of Metal–Organic Frameworks (MOFs) Coupled with Enzymes as Biosensors
Electrochem 2022, 3(1), 89-113; https://doi.org/10.3390/electrochem3010006 - 01 Feb 2022
Cited by 1 | Viewed by 1092
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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Article
Theoretical and Numerical Analysis of Nonlinear Processes in Amperometric Enzyme Electrodes with Cyclic Substrate Conversion
Electrochem 2022, 3(1), 70-88; https://doi.org/10.3390/electrochem3010005 - 25 Jan 2022
Viewed by 1131
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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Article
Modification of Cu(111) Surface with Alkylphosphonic Acids in Aqueous and Ethanol Solution—An Experimental and Theoretical Study
Electrochem 2022, 3(1), 58-69; https://doi.org/10.3390/electrochem3010004 - 16 Jan 2022
Viewed by 849
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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Article
Application of Machine Learning in Battery: State of Charge Estimation Using Feed Forward Neural Network for Sodium-Ion Battery
Electrochem 2022, 3(1), 42-57; https://doi.org/10.3390/electrochem3010003 - 11 Jan 2022
Cited by 1 | Viewed by 918
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 Na0.67Fe0.5Mn0.5O2 (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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Article
An Experimental and Theoretical Investigation of the Efficacy of Pantoprazole as a Corrosion Inhibitor for Mild Steel in an Acidic Medium
Electrochem 2022, 3(1), 28-41; https://doi.org/10.3390/electrochem3010002 - 06 Jan 2022
Viewed by 983
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: 2022

Review
Recent Advancements in the Synthesis and Application of Carbon-Based Catalysts in the ORR
Electrochem 2022, 3(1), 1-27; https://doi.org/10.3390/electrochem3010001 - 27 Dec 2021
Cited by 2 | Viewed by 1183
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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Review
Recent Applications of Molecular Structures at Silicon Anode Interfaces
Electrochem 2021, 2(4), 664-676; https://doi.org/10.3390/electrochem2040041 - 18 Dec 2021
Viewed by 1079
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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Article
Coupled Electrochemical-Thermal Simulations and Validation of Minichannel Cold-Plate Water-Cooled Prismatic 20 Ah LiFePO4 Battery
Electrochem 2021, 2(4), 643-663; https://doi.org/10.3390/electrochem2040040 - 22 Nov 2021
Cited by 40 | Viewed by 1448
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, Tmax and temperature difference, ΔT) 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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Article
Double-Layer Capacitances Caused by Ion–Solvent Interaction in the Form of Langmuir-Typed Concentration Dependence
Electrochem 2021, 2(4), 631-642; https://doi.org/10.3390/electrochem2040039 - 18 Nov 2021
Viewed by 881
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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Review
Catalysts for Oxygen Reduction Reaction in the Polymer Electrolyte Membrane Fuel Cells: A Brief Review
Electrochem 2021, 2(4), 590-603; https://doi.org/10.3390/electrochem2040037 - 22 Oct 2021
Cited by 1 | Viewed by 1080
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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Review
Fabrication of Metal/Carbon Nanotube Composites by Electrochemical Deposition
Electrochem 2021, 2(4), 563-589; https://doi.org/10.3390/electrochem2040036 - 21 Oct 2021
Cited by 1 | Viewed by 1244
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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Article
Effect of Cr Content on Corrosion Resistance of Low-Cr Alloy Steels Studied by Surface and Electrochemical Techniques
Electrochem 2021, 2(4), 546-562; https://doi.org/10.3390/electrochem2040035 - 18 Oct 2021
Cited by 1 | Viewed by 880
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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Article
Synthesis and Characterization of Supercapacitor Materials from Soy
Electrochem 2021, 2(4), 534-545; https://doi.org/10.3390/electrochem2040034 - 14 Oct 2021
Cited by 1 | Viewed by 951
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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Article
Electrodeposition of Cu-Mn Films as Precursor Alloys for the Synthesis of Nanoporous Cu
Electrochem 2021, 2(3), 520-533; https://doi.org/10.3390/electrochem2030033 - 13 Sep 2021
Viewed by 1247
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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Review
Graphene Quantum Dots-Based Nanocomposites Applied in Electrochemical Sensors: A Recent Survey
Electrochem 2021, 2(3), 490-519; https://doi.org/10.3390/electrochem2030032 - 06 Sep 2021
Cited by 7 | Viewed by 1527
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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Article
Light in Electrochemistry
Electrochem 2021, 2(3), 472-489; https://doi.org/10.3390/electrochem2030031 - 26 Aug 2021
Cited by 2 | Viewed by 1294
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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Review
Review on Interface and Interphase Issues in Sulfide Solid-State Electrolytes for All-Solid-State Li-Metal Batteries
Electrochem 2021, 2(3), 452-471; https://doi.org/10.3390/electrochem2030030 - 02 Aug 2021
Cited by 2 | Viewed by 2216
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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Article
Synthesis of Nickel Fumarate and Its Electrochemical Properties for Li-Ion Batteries
Electrochem 2021, 2(3), 439-451; https://doi.org/10.3390/electrochem2030029 - 27 Jul 2021
Cited by 4 | Viewed by 1288
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 g1. Full article
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Article
A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications
Electrochem 2021, 2(3), 427-438; https://doi.org/10.3390/electrochem2030028 - 26 Jul 2021
Cited by 3 | Viewed by 1526
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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Article
Reduction of Cd(II) Ions in the Presence of Tetraethylammonium Cations. Adsorption Effect on the Electrode Process
Electrochem 2021, 2(3), 415-426; https://doi.org/10.3390/electrochem2030027 - 23 Jul 2021
Viewed by 993
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 E1/2, half wave potential, and DO, 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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Review
Crystal Structure and Preparation of Li7La3Zr2O12 (LLZO) Solid-State Electrolyte and Doping Impacts on the Conductivity: An Overview
Electrochem 2021, 2(3), 390-414; https://doi.org/10.3390/electrochem2030026 - 19 Jul 2021
Cited by 4 | Viewed by 2904
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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Review
Developments of the Electroactive Materials for Non-Enzymatic Glucose Sensing and Their Mechanisms
Electrochem 2021, 2(2), 347-389; https://doi.org/10.3390/electrochem2020025 - 21 Jun 2021
Cited by 1 | Viewed by 1405
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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Article
Synergistic Effect of Polymorphs in Doped NaNi0.5Mn0.5O2 Cathode Material for Improving Electrochemical Performances in Na-Batteries
Electrochem 2021, 2(2), 335-346; https://doi.org/10.3390/electrochem2020024 - 04 Jun 2021
Cited by 1 | Viewed by 1394
Abstract
Layered NaNi0.5Mn0.5O2, 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 NaNi0.5Mn0.5O2, 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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Article
Understanding the Effect of Zn Doping on Stability of Cobalt-Free P2-Na0.60Fe0.5Mn0.5O2 Cathode for Sodium Ion Batteries
Electrochem 2021, 2(2), 323-334; https://doi.org/10.3390/electrochem2020023 - 02 Jun 2021
Cited by 3 | Viewed by 1618
Abstract
In this work, we report a sol-gel synthesis-based Zn-doped Na0.6Fe0.5Mn0.5O2 (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 Na0.6Fe0.5Mn0.5O2 (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 Fe3+/4+ even after 10 cycles compared to NFM. Full article
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Article
Characterization and Electrocatalytic Performance of Molasses Derived Co-Doped (P, N) and Tri-Doped (Si, P, N) Carbon for the ORR
Electrochem 2021, 2(2), 311-322; https://doi.org/10.3390/electrochem2020022 - 02 Jun 2021
Cited by 1 | Viewed by 1540
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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Article
Efficient Electrocatalytic Approach to Spiro[Furo[3,2-b]pyran-2,5′-pyrimidine] Scaffold as Inhibitor of Aldose Reductase
Electrochem 2021, 2(2), 295-310; https://doi.org/10.3390/electrochem2020021 - 25 May 2021
Viewed by 1504
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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Review
A Short Review on Electrochemical Sensing of Commercial Dyes in Real Samples Using Carbon Paste Electrodes
Electrochem 2021, 2(2), 274-294; https://doi.org/10.3390/electrochem2020020 - 25 May 2021
Cited by 4 | Viewed by 1441
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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Article
Solid-State Electrochemical Energy Storage Based on Soluble Melanin
Electrochem 2021, 2(2), 264-273; https://doi.org/10.3390/electrochem2020019 - 25 May 2021
Cited by 4 | Viewed by 1129
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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Article
Development of an Electrochemical Sensor Based on Nanocomposite of Fe3O4@SiO2 and Multiwalled Carbon Nanotubes for Determination of Tetracycline in Real Samples
Electrochem 2021, 2(2), 251-263; https://doi.org/10.3390/electrochem2020018 - 18 May 2021
Cited by 1 | Viewed by 1025
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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Article
Electrolytic Reduction of Titanium Dioxide in Molten LiCl–Li2O
Electrochem 2021, 2(2), 224-235; https://doi.org/10.3390/electrochem2020016 - 27 Apr 2021
Viewed by 985
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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Article
Electrodeposition of Aluminum in the 1-Ethyl-3-Methylimidazolium Tetrachloroaluminate Ionic Liquid
Electrochem 2021, 2(2), 185-196; https://doi.org/10.3390/electrochem2020013 - 26 Mar 2021
Cited by 1 | Viewed by 1286
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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Article
Investigation of the Applicability of Helium-Based Cooling System for Li-Ion Batteries
Electrochem 2021, 2(1), 135-148; https://doi.org/10.3390/electrochem2010011 - 08 Mar 2021
Cited by 5 | Viewed by 1247
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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Review
Wearable Nanogenerators: Working Principle and Self-Powered Biosensors Applications
Electrochem 2021, 2(1), 118-134; https://doi.org/10.3390/electrochem2010010 - 28 Feb 2021
Cited by 1 | Viewed by 1300
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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