Electrochimica Acta最新文献

To boost the performance of non-aqueous redox flow batteries (RFBs), it is important to synergistically improve the flow/mass transfer efficiencies and the uniformity of overpotential distribution into the porous electrode. In this work, electrostatic spinning technology is developed to propose a novel porous electrode with gradient pore distribution both in the in-plane and through-plane directions, and applied in deep eutectic solvent (DES) electrolyte-based iron-vanadium RFB. On the one hand, the new in-plane gradient design modifies the distribution of reactive species of electrode near the membrane side, resulting in the decreasing polarization loss. On the other hand, the increasing porosity of electrodes from the flow field side to the membrane side attains a trade-off between the charge transfer and the electrolyte flow resistances. According to the experimental results, compared to the graphite felt electrode, the energy efficiency of this RFB with three-dimensional gradient electrode improves by 74.2 % at a current density of 10 mA·cm⁻². Moreover, the numerical simulation reveals the reactive transfer behaviors of three-dimensional gradient porous electrode. The results show that the proposed three-dimensional gradient design can enhance the uniformity of overpotential distribution and achieve the decrease of polarization resistance, thus improving the performance of DES electrolyte-based iron-vanadium RFB effectively.

This research introduces a novel approach to electrocatalysis for sustainable energy generation, revealing the MnCoCrV LDH@SCDs composite supported by nickel foam (NF) as a high-performance catalyst specifically designed for seawater electrolysis. Constructed by incorporating sulfur-doped carbon dots (SCDs) into MnCoCrV layered double hydroxide (LDH) and depositing them onto a nickel foam substrate, this electrocatalyst demonstrates exceptional efficiency in the oxygen evolution reaction (OER) under alkaline seawater conditions. MnCoCrV LDH@SCDs/NF attains a noteworthy current density of 10 mA/cm² with a minimal overpotential of 209.4 mV. Additionally, it demonstrates a reduced Tafel value of 81.5 mV/dec, indicating faster kinetics. The electrode maintains impressive long-term stability, sustaining efficiency for approximately 50 h at a constant current density of 10 mA/cm². The increased surface area and reduced charge transfer resistance contribute to substantial electrocatalytic performance in seawater. This performance is primarily attributed to improved conductivity, resulting from synergistic contributions from high-valence-state vanadium ions and electrochemically active functional groups in SCDs. The MnCoCrV LDH@SCDs/NF electrocatalyst stands out for its intricate features that not only promote efficient electron transfer but also effectively counteract interference from chloride anions in seawater electrolysis. This study underscores the innovative nature of MnCoCrV LDH@SCDs/NF as a pivotal development in electrocatalyst research, offering a promising avenue for harnessing renewable energy from seawater.

Cu-Sn/nano-SiO₂ composite materials are fabricated through electrodeposition process coupled with precise thermal treatment, which employs hexadecyl trimethyl ammonium bromide to guarantee the even distribution of nano-SiO₂ particles within the Cu-Sn alloy framework. The characterization results indicate that integrating nano-SiO₂ into the Cu-Sn matrix effectively prevents active particles from detaching from the copper foil current collector. By adjusting the current density, the electrochemical performance of the Cu-Sn/nano-SiO₂ composite electrode is significantly enhanced. Specifically, the initial charge and discharge specific capacities of the composite electrolyte are approximately 746.6 and 1470.8 mAh/g at 100 mA/g, respectively. Moreover, the cell can still maintain a discharge specific capacity of 358.6 mAh/g after 100 cycles. Furthermore, the cell demonstrates an improved lithium-ion diffusion coefficient of approximately 9.639 × 10^–15 cm²/s and a lower transfer resistance of 54.65 Ω. Therefore, a direct approach of fabricating the Cu-Sn/nano-SiO₂ composite electrode with enhanced electrochemical properties may provide valuable guidance for alloy anodes in the energy storage field.

In this foreword, the Symposium on Electrochemical Impedance Spectroscopy (EIS12–2023), which was held by Beijing University of Chemical Technology and Tsinghua University in Beijing from July 2 to 7, 2023, was in details introduced. It was the first time that EIS12 -2023 took place in China since it was established in France 1989. At the opening ceremony, a film illustrating the history of the conference on electrochemical impedance spectroscopy was also shown. Meanwhile, the Claude Awards were given to Prof. Annick Hubin from Vrije Universiteit Brussel in Belgium and Prof. Jianqing Zhang from Zhejiang University in China. During EIS12–2023, 15 plenary talks, 21 invited talks in the corrosion session and in memory of Prof. Chunan Cao, 10 keynote talks in the energy and measurement sessions were presented. There were also 51 posters and 54 talks. Xingyue Yong from Beijing University of Chemical Technology and Assistant Professor Burak Ulgut from Bilkent University, Turkey were elected as new members of the Technical Committee of International Electrochemical Impedance Spectroscopy Additionally, it was decided that the 13th International Symposium on Electrochemical Impedance Spectroscopy will be held in Brazil in November 2026. EIS12–2023 organizing committee sincerely thanks everyone for supporting EIS12–2023 and express its great gratitude to Prof. Sotiris Sotiropoulos, the Special Issues Editor of Electrochimica Acta, for his contribution in making this Special Issue possible.

In alkaline solutions hydrogen adsorption involves the splitting of a water molecule, which can be catalysed by the presence of cations. We have analysed the adsorption processes from a water molecule approaching the surface of a graphene bilayer containing a vacancy, both in the presence and in the absence of cations (Na⁺, K⁺ and Mg²⁺) by quantum molecular dynamics using DFT based tight-binding. A cation near the interface induces a region with positive excess charge in its solvation shell, which facilitates the orientation of the reacting water molecule with the hydrogen towards the surface. This concerted mechanism catalyses the hydrogenation and stabilizes the resulting hydroxyl. Therefore in the presence of cations the hydrogen evolution reaction occurs spontaneously at less negative charges than in the absence. Thus our investigations suggest a detailed scenario for the catalytic effect of cations both on the spatial and temporal nano-scale.

This study focuses on the electrochemical detection of 4-nitrophenol (4-NP) utilizing Ag@Ag₂MoO₄ microcubes, PANI-Ppy, and their nanohybrid. 4-NP is known for its environmental hazards and high toxicity, making its detection crucial. The synthesis of Ag@Ag₂MoO₄/PANI-Ppy is employs a microwave technique, followed by electrode fabrication using a drop-casting method. Structural, optical, morphological, and electrochemical characterizations were conducted to evaluate their efficacy for 4-NP detection. The modified electrode demonstrated a limit of detection (LOD) of 72 nM and a limit of quantification (LOQ) of 241.31 nM, with excellent selectivity against various interferences. Real water samples validated the modified electrode's viability, yielding positive recovery values. A comprehensive mechanism for the electrochemical detection of 4-NP is proposed.

Electrochemical synthesis of hydrogen peroxide (H₂O₂) via oxygen reduction reactions (ORR) represents a green, environmentally friendly, and decentralized alternative to the conventional, fossil-based, and centralized anthraquinone process. This work presents a flow-through module using commercial carbon black (CB) as a catalyst at current densities of up to 120 mA cm⁻². Acid treatment of CB increases its oxygen content, leading to Faraday efficiency (FE) values above 80 % with a maximum specific H₂O₂ production rate of 64.3 mg cm⁻² h⁻¹. Additionally, the effect of catalyst loading on the functionality of a gas diffusion electrode (GDE) at 120 mA cm⁻² and over long-term electrolysis (7.5 h) is investigated, discussing the detrimental penetration of electrolyte into the GDE due to the enhanced electro-wetting, which shifts the three-phase boundary toward the gas channel side. This study underscores the critical significance of optimizing the parameters involved in GDE fabrication, especially under high current densities and extended operational periods, propelling our understanding toward the development of a robust flow-through module for the electro-generation of H₂O₂.

Phosphoric acid (PA), utilized as an electrolyte in high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), has been observed to exert a detrimental effect on oxygen reduction reaction (ORR) electrocatalyst, consequently compromising cell performance. To comprehensively elucidate the impact of phosphoric acid on ORR, this study employs a range of electrochemical techniques, including electrochemical impedance spectroscopy and voltammetry method. The negative influence of PA on commercial Pt/C electrocatalyst manifests differently under various potentials and PA concentrations. Upon the introduction of PA, the decay rate and amplitude of ECSA, as calculated by H_upd adatoms, are notably smaller compared to the kinetic current density generated by the oxygen reduction reaction. Particularly, in the kinetic-controlled potential range, the negative impact of PA becomes more pronounced at higher electrode potentials, accompanied by a significantly steeper Tafel slope. Additionally, the EIS results suggest that phosphoric acid may gradually transform into polyphosphoric acid at a high concentration, accentuating the poisoning effect of PA under steady-state conditions. However, a high PA concentration can substantially alter the electrolyte properties, potentially leading to an inaccurate assessment of PA tolerance in electrocatalysts. Hence, it is imperative to consider the appropriate PA concentration when evaluating PA tolerance and to discern the poisoning mechanism under different electrode potentials.

Neural-electrode devices with adequate charge injection capacity, long operating lifetime and excellent biocompatibility with interfaced tissues are essential to treat chronic neurological disorders. The device's efficiency hinges on the electrochemical properties of the electrode material, prompting extensive research on diverse material surfaces. Here, we investigate the electrochemical stability and biocompatibility of titanium nitride (TiN) nanowires (NWs) synthesized previously through the novel plasma enhanced chemical vapor deposition (PECVD) utilizing lower temperature as compared to conventional methods. These TiN-NWs were compared with TiN thin films, shedding light on their respective performances. TiN-NWs electrode revealed far superior electrochemical stability over 1000 cycles, achieving a capacitance retention of 93 % as compared to 68 % to that of TiN film electrode, under ambient conditions with dissolved oxygen. Additionally, impedance of TiN-NWs showed almost no change with cycling as compared to the film electrode. Moreover, our in-vitro cell culture spanning 20 days exhibited excellent biocompatibility for both substrates. Interestingly, cell distribution on the NWs appeared more dispersed with fewer clusters, potentially facilitating controlled electrical stimulation. These findings not only highlights the potential use of TiN-NWs for chronic stimulation of neurons, but also shows that surface morphology has a potential effect in minimising surface oxidation and improving electrochemial performance of the material.