Research

19 pages, 2799 KiB

Open AccessArticle

Facile and Low-Cost SPE Modification Towards Ultra-Sensitive Organophosphorus and Carbamate Pesticide Detection in Olive Oil

by Dionysios Soulis, Marianna Trigazi, George Tsekenis, Chrysoula Chandrinou, Apostolos Klinakis and Ioanna Zergioti

Molecules 2020, 25(21), 4988; https://doi.org/10.3390/molecules25214988 - 28 Oct 2020

Cited by 17 | Viewed by 2851

Abstract

Despite the fact that a considerable amount of effort has been invested in the development of biosensors for the detection of pesticides, there is still a lack of a simple and low-cost platform that can reliably and sensitively detect their presence in real [...] Read more.

Despite the fact that a considerable amount of effort has been invested in the development of biosensors for the detection of pesticides, there is still a lack of a simple and low-cost platform that can reliably and sensitively detect their presence in real samples. Herein, an enzyme-based biosensor for the determination of both carbamate and organophosphorus pesticides is presented that is based on acetylcholinesterase (AChE) immobilized on commercially available screen-printed carbon electrodes (SPEs) modified with carbon black (CB), as a means to enhance their conductivity. Most interestingly, two different methodologies to deposit the enzyme onto the sensor surfaces were followed; strikingly different results were obtained depending on the family of pesticides under investigation. Furthermore, and towards the uniform application of the functionalization layer onto the SPEs’ surfaces, the laser induced forward transfer (LIFT) technique was employed in conjunction with CB functionalization, which allowed a considerable improvement of the sensor’s performance. Under the optimized conditions, the fabricated sensors can effectively detect carbofuran in a linear range from 1.1 × 10⁻⁹ to 2.3 × 10⁻⁸ mol/L, with a limit of detection equal to 0.6 × 10⁻⁹ mol/L and chlorpyrifos in a linear range from 0.7 × 10⁻⁹ up to 1.4 × 10⁻⁸ mol/L and a limit of detection 0.4 × 10⁻⁹ mol/L in buffer. The developed biosensor was also interrogated with olive oil samples, and was able to detect both pesticides at concentrations below 10 ppb, which is the maximum residue limit permitted by the European Food Safety Authority. Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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10 pages, 5632 KiB

Open AccessArticle

Real-Time Analysis of the Stability of Oil-In-Water Pickering Emulsion by Electrochemical Impedance Spectroscopy

by Qiuyan Jiang, Ning Sun, Parveen Kumar, Qiuhong Li, Bo Liu, Aixiang Li, Weiwei Wang and Zengli Gao

Molecules 2020, 25(12), 2904; https://doi.org/10.3390/molecules25122904 - 24 Jun 2020

Cited by 4 | Viewed by 2852

Abstract

In this paper, electrical impedance spectroscopy (EIS) was applied to investigate the stability of oil-in-water (O/W) Pickering emulsions prepared with negatively charged silica nanoparticles in combination with a trace amount of redox switchable fluorescent molecules, ferrocene azine (FcA). Electrical impedance values of emulsions [...] Read more.

In this paper, electrical impedance spectroscopy (EIS) was applied to investigate the stability of oil-in-water (O/W) Pickering emulsions prepared with negatively charged silica nanoparticles in combination with a trace amount of redox switchable fluorescent molecules, ferrocene azine (FcA). Electrical impedance values of emulsions obtained at different emulsification speeds were estimated according to the frequency response data with frequencies ranging from 1 MHz to 1 Hz. The equivalent circuit model of toluene-in-water emulsion was established by the resistor (R_O/W) and capacitor (C_O/W) in parallel connection. Nyquist diagrams for the emulsions prepared by toluene and water were characterized by the formation of one semi-circle. The droplet size distribution is one of the important factors that affect the stability of the emulsion, except for the volume fraction of water and oil, the size of stabilizing particles, etc. The average particle size of the emulsion droplets decreased as the emulsification speed increased, indicating the higher stability of the emulsion. It was found that the fitted impedance value R_O/W of the emulsion decreased with decreasing particle size prepared at different emulsification speeds and storage time by performing real-time EIS detection techniques. The results suggested that EIS could be used to characterize the stability of a toluene-in-water emulsion stabilized by FcA modified silica nanoparticles. Moreover, based on the good electrochemical activity of the FcA molecule, the stability of the Pickering emulsion can be modulated by adding oxidant and reductant and detected by EIS in real-time. Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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14 pages, 3593 KiB

Open AccessArticle

Towards a High-Power Si@graphite Anode for Lithium Ion Batteries through a Wet Ball Milling Process

by Marta Cabello, Emanuele Gucciardi, Alvaro Herrán, Daniel Carriazo, Aitor Villaverde and Teófilo Rojo

Molecules 2020, 25(11), 2494; https://doi.org/10.3390/molecules25112494 - 27 May 2020

Cited by 32 | Viewed by 6561

Abstract

Silicon-based anodes are extensively studied as an alternative to graphite for lithium ion batteries. However, silicon particles suffer larges changes in their volume (about 280%) during cycling, which lead to particles cracking and breakage of the solid electrolyte interphase. This process induces continuous [...] Read more.

Silicon-based anodes are extensively studied as an alternative to graphite for lithium ion batteries. However, silicon particles suffer larges changes in their volume (about 280%) during cycling, which lead to particles cracking and breakage of the solid electrolyte interphase. This process induces continuous irreversible electrolyte decomposition that strongly reduces the battery life. In this research work, different silicon@graphite anodes have been prepared through a facile and scalable ball milling synthesis and have been tested in lithium batteries. The morphology and structure of the different samples have been studied using X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, and scanning and transmission electron microscopy. We show how the incorporation of an organic solvent in the synthesis procedure prevents particles agglomeration and leads to a suitable distribution of particles and intimate contact between them. Moreover, the importance of the microstructure of the obtained silicon@graphite electrodes is pointed out. The silicon@graphite anode resulted from the wet ball milling route, which presents capacity values of 850 mA h/g and excellent capacity retention at high current density (≈800 mA h/g at 5 A/g). Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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11 pages, 4267 KiB

Open AccessArticle

Study on Different Water-Based Binders for Li₄Ti₅O₁₂ Electrodes

by Christina Toigo, Catia Arbizzani, Karl-Heinz Pettinger and Maurizio Biso

Molecules 2020, 25(10), 2443; https://doi.org/10.3390/molecules25102443 - 24 May 2020

Cited by 16 | Viewed by 3647

Abstract

In this study, Li₄Ti₅O₁₂ (LTO) electrodes with different types of water-soluble binders are successfully coated upon aluminum foil. Electrodes containing solely sodium alginate (SA) as a binder or a mixed PVDF/carboxymethyl cellulose (CMC) binder show the most stable [...] Read more.

In this study, Li₄Ti₅O₁₂ (LTO) electrodes with different types of water-soluble binders are successfully coated upon aluminum foil. Electrodes containing solely sodium alginate (SA) as a binder or a mixed PVDF/carboxymethyl cellulose (CMC) binder show the most stable performance in 1 M LiPF₆ in EC/DMC 1:1 in half cell vs. Li, with respect to cycle stability over 100 cycles at 1 C. The electrodes processed with a mixture of PVDF/SA show considerable fading and slightly worse values for rate capability. Each one of the different binders used is eco-friendly, and the whole processing can be performed without the use of organic solvents. Further advantages covering the whole production and recycling process, as well as safety issues during operation, encourage deeper research in this area. Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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14 pages, 3413 KiB

Open AccessCommunication

All-Solid-State Lithium Ion Batteries Using Self-Organized TiO₂ Nanotubes Grown from Ti-6Al-4V Alloy

by Vinsensia Ade Sugiawati, Florence Vacandio and Thierry Djenizian

Molecules 2020, 25(9), 2121; https://doi.org/10.3390/molecules25092121 - 01 May 2020

Cited by 10 | Viewed by 3197

Abstract

All-solid-state batteries were fabricated by assembling a layer of self-organized TiO₂ nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO₄ as a cathode. The synthesis of self-organized TiO₂ NTs [...] Read more.

All-solid-state batteries were fabricated by assembling a layer of self-organized TiO₂ nanotubes grown on as anode, a thin-film of polymer as an electrolyte and separator, and a layer of composite LiFePO₄ as a cathode. The synthesis of self-organized TiO₂ NTs from Ti-6Al-4V alloy was carried out via one-step electrochemical anodization in a fluoride ethylene glycol containing electrolytes. The electrodeposition of the polymer electrolyte onto anatase TiO₂ NTs was performed by cyclic voltammetry. The anodized Ti-6Al-4V alloys were characterized by scanning electron microscopy and X-ray diffraction. The electrochemical properties of the anodized Ti-6Al-4V alloys were investigated by cyclic voltammetry and chronopotentiometry techniques. The full-cell shows a high first-cycle Coulombic efficiency of 96.8% with a capacity retention of 97.4% after 50 cycles and delivers a stable discharge capacity of 63 μAh cm⁻² μm⁻¹ (119 mAh g⁻¹) at a kinetic rate of C/10. Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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9 pages, 2494 KiB

Open AccessArticle

Recognition of V³⁺/V⁴⁺/V⁵⁺ Multielectron Reactions in Na₃V(PO₄)₂: A Potential High Energy Density Cathode for Sodium-Ion Batteries

by Rui Liu, Ziteng Liang, Yuxuan Xiang, Weimin Zhao, Haodong Liu, Yan Chen, Ke An and Yong Yang

Molecules 2020, 25(4), 1000; https://doi.org/10.3390/molecules25041000 - 24 Feb 2020

Cited by 10 | Viewed by 4124

Abstract

Na₃V(PO₄)₂ was reported recently as a novel cathode material with high theoretical energy density for Sodium-ion batteries (SIBs). However, whether V³⁺/V⁴⁺/V⁵⁺ multielectron reactions can be realized during the charging process is still an [...] Read more.

Na₃V(PO₄)₂ was reported recently as a novel cathode material with high theoretical energy density for Sodium-ion batteries (SIBs). However, whether V³⁺/V⁴⁺/V⁵⁺ multielectron reactions can be realized during the charging process is still an open question. In this work, Na₃V(PO₄)₂ is synthesized by using a solid-state method. Its atomic composition and crystal structure are verified by X-ray diffraction (XRD) and neutron diffraction (ND) joint refinement. The electrochemical performance of Na₃V(PO₄)₂ is evaluated in two different voltage windows, namely 2.5–3.8 and 2.5–4.3 V. ⁵¹V solid-state NMR (ssNMR) results disclose the presence of V⁵⁺ in Na_2−xV(PO₄)₂ when charging Na₃V(PO₄)₂ to 4.3 V, confirming Na₃V(PO₄)₂ is a potential high energy density cathode through realization of V³⁺/V⁴⁺/V⁵⁺ multielectron reactions. Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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9 pages, 2441 KiB

Open AccessFeature PaperArticle

Sustainable and Environmentally Friendly Na and Mg Aqueous Hybrid Batteries Using Na and K Birnessites

by Francisco Gálvez, Marta Cabello, Pedro Lavela, Gregorio F. Ortiz and José L. Tirado

Molecules 2020, 25(4), 924; https://doi.org/10.3390/molecules25040924 - 19 Feb 2020

Cited by 7 | Viewed by 2542

Abstract

Sodium and magnesium batteries with intercalation electrodes are currently alternatives of great interest to lithium in stationary applications, such as distribution networks or renewable energies. Hydrated laminar oxides such as birnessites are an attractive cathode material for these batteries. Sodium and potassium birnessite [...] Read more.

Sodium and magnesium batteries with intercalation electrodes are currently alternatives of great interest to lithium in stationary applications, such as distribution networks or renewable energies. Hydrated laminar oxides such as birnessites are an attractive cathode material for these batteries. Sodium and potassium birnessite samples have been synthesized by thermal and hydrothermal oxidation methods. Hybrid electrochemical cells have been built using potassium birnessite in aqueous sodium electrolyte, when starting in discharge and with a capacity slightly higher than 70 mA h g⁻¹. Hydrothermal synthesis generally shows slightly poorer electrochemical behavior than their thermal counterparts in both sodium and potassium batteries. The study on hybrid electrolytes has resulted in the successful galvanostatic cycling of both sodium birnessite and potassium birnessite in aqueous magnesium electrolyte, with maximum capacities of 85 and 50 mA h g⁻¹, respectively. Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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8 pages, 1229 KiB

Open AccessCommunication

Thermal Decomposition Study on Li₂O₂ for Li₂NiO₂ Synthesis as a Sacrificing Positive Additive of Lithium-Ion Batteries

by Jaekwang Kim, Hyunchul Kang, Keebum Hwang and Songhun Yoon

Molecules 2019, 24(24), 4624; https://doi.org/10.3390/molecules24244624 - 17 Dec 2019

Cited by 14 | Viewed by 3928

Abstract

Herein, thermal decomposition experiments of lithium peroxide (Li₂O₂) were performed to prepare a precursor (Li₂O) for sacrificing cathode material, Li₂NiO₂. The Li₂O₂ was prepared by a hydrometallurgical reaction between LiOH·H [...] Read more.

Herein, thermal decomposition experiments of lithium peroxide (Li₂O₂) were performed to prepare a precursor (Li₂O) for sacrificing cathode material, Li₂NiO₂. The Li₂O₂ was prepared by a hydrometallurgical reaction between LiOH·H₂O and H₂O₂. The overall reaction during annealing was found to involve the following three steps: (1) dehydration of LiOH·H₂O, (2) decomposition of Li₂O₂, and (3) pyrolysis of the remaining anhydrous LiOH. This stepwise reaction was elucidated by thermal gravimetric and quantitative X-ray diffraction analyses. Furthermore, over-lithiated lithium nickel oxide (Li₂NiO₂) using our lithium precursor was synthesized, which exhibited a larger yield of 90.9% and higher irreversible capacity of 261 to 265 mAh g⁻¹ than the sample prepared by commercially purchased Li₂O (45.6% and 177 to 185 mAh g⁻¹, respectively) due to optimal powder preparation conditions. Full article

(This article belongs to the Special Issue Next Generation Electrode Material)

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