ChemElectroChem最新文献

We review recent computational advances in understanding the energy storage mechanisms of pseudocapacitive electrode materials, with particular emphasis on first-principles approaches, including density functional theory (DFT), joint density functional theory (JDFT), and computational electrochemistry at electrode/electrolyte interfaces. Representative classes of pseudocapacitive materials are systematically discussed together with the theoretical foundations, practical methodologies, and representative applications of first-principles calculations. Particular attention is devoted to quantitative descriptions of the competition between electric double-layer formation and Faradaic redox reactions, which governs pseudocapacitive charge storage under realistic electrochemical conditions. This review also summarizes practical considerations for computational modeling, software selection, and interpretation of computational results, providing a practical guide for researchers working at the interface between computational and experimental electrochemistry. Finally, recent developments in computational electrochemistry, together with emerging methodologies that extend first-principles calculations, including machine-learning potential, computational electrochemistry, and emerging electrochemoinformatics, are highlighted, along with their future prospects for predictive materials design.

Oxygen vacancy-engineered CoSnO₃/reduced graphene oxide (CoSnO₃/rGO) serves as a durable cathode electrocatalyst for vanadium redox flow batteries (VRFBs). Structural and spectroscopic analyses confirm the formation of defect-rich amorphous CoSnO₃ uniformly integrated with a conductive rGO network, which exhibits a high fraction (22.54%) of oxygen vacancy-related defect oxygen species as indicated by combined X-ray photoelectron spectroscopy and electron paramagnetic resonance measurements. These defect sites facilitate VO²⁺/VO₂⁺ adsorption and accelerate vanadium redox kinetics. At the same time, the synergistic interaction between CoSnO₃ nanocubes and rGO enhances electron transport, increases active-site exposure, and promotes ion diffusion. When deposited onto heat-treated graphite felt (HGF), the CoSnO₃/rGO-modified positive electrode exhibits reduced overpotential, improved electrochemical reversibility, and stable high-rate cycling performance in VRFB single cells. The assembled VRFB achieves energy efficiencies of 84.12% at 80 mA cm⁻² and 74.22% at 160 mA cm⁻², significantly surpassing the efficiencies of pristine graphite felt under identical conditions. These findings show that defect-engineered mixed transition-metal oxide–carbon hybrids are a promising design strategy for high-performance VRFB cathodes and offer insights for developing next-generation large-scale electrochemical energy storage systems.

Hydroxylated aromatic molecules, namely phenol derivatives, catecholamines, and naphthalenes, are known for their acidity, redox properties, and reactivity with nucleophiles. This versatile chemistry is a landmark in living organisms. There, these molecules afford adhesion, stability, and protection against parasites. The large diversity of functional groups and their cross-reactivity, however, complicate the characterization of the obtained insoluble reaction products. In this landscape, electrochemical deposition of members of this vast family of molecules allows to eliminate toxic phenol derivatives but appears also as a way to produce functional coatings. This review describes the possible fate of surface-controlled electrochemical processes of phenol derivatives, catecholamines, and hydroxylated naphthalenes. Under strong oxidative conditions, the solutes are mineralized, but in the electrochemical stability window, the electrode may undergo passivation or deposition of porous, eventually conductive films. The major results obtained over the last 50 years will be discussed in relation to the molecular structure, the solvent, pH, and potential sweep rate. Some perspectives will be given to reach a deeper structure–solvent–pH–electrode relationship concerning the fate of the electrochemical experiments performed on those molecules. In particular, the proximity of the two hydroxyl groups will be proposed as a design tool to produce thick and porous coatings.

The development of effective catalysts for alkaline water electrolysis is strongly demanded for green hydrogen production. In the present study, we synthesized various crystalline metal oxide and phosphate nanoparticles and evaluated their catalytic performance for the oxygen evolution reaction by linear sweep voltammetry measurements. Among approximately 50 types of nanoparticles and benchmark catalysts (e.g., IrO₂ and RuO₂), Fe₃O₃PO₄ exhibited the lowest potential (1.57 ± 0.02 V vs. RHE) at a current density of 0.5 A cm⁻². Furthermore, ON/OFF durability tests simulating system startup and shutdown revealed that this material exhibits high durability and a degradation rate of only 15 μV cycle⁻¹ during 4000 cycles. Spectroscopic analyses, including inductively coupled plasma−atomic emission, Raman, X-ray absorption, and X-ray photoelectron spectroscopy likely suggested that Fe₃O₃PO₄ is electrochemically activated to form a γ-FeOOH-type species accompanied by leaching of phosphorus species from the structure during the reaction. In addition, PO₄³⁻ species on the catalyst surface may affect both OER activity and the durability of the resultant γ-FeOOH electrocatalyst under reverse current conditions.

Hydrogen production via iodide oxidation reaction-coupled hybrid electrolysis is an emerging approach in which the system-level role of anolyte composition remains poorly understood. A systematic investigation on the influence of anolyte composition using hydroiodic acid (HI) and iodine (I₂) by varying I₂/HI and HI/H₂O ratios is presented. The behavior has been examined at both electrode scale (three-electrode configuration) and device scale (membrane-separated two-compartment cell). A mathematical framework is developed to deconvolute the contributions of the overall cell voltage into the overpotential components. Model-based analysis reveals that, although anolyte composition influences anode kinetics, activation overpotential changes are negligible at the full-cell level. Instead, the cell voltage is governed by the composition-dependent open-circuit voltage and cell resistance. A lower operating cell potential is achieved at lower I₂/HI ratios and higher HI/H₂O ratios. While the azeotropic HI/H₂O ratio (∼0.186) represents a practical upper limit, the optimal I₂/HI ratio is dictated by the downstream processing requirements of the anolyte. Continuous hydrogen production is demonstrated at three I₂/HI ratios at the azeotropic HI/H₂O ratio and two current densities, achieving 0.01–0.015 mL s⁻¹ production rate with a high current efficiency (93.7%–96.8%). The specific energy consumption increases with both I₂/HI ratio and current density.

Aqueous zinc-ion batteries represent a compelling pathway toward safe and low-cost grid-scale energy storage. Yet, the persistent instability of the zinc anode, given by dendrite formation, hydrogen evolution, and corrosion, remains an obstacle to their practical deployment. Here, we report on the use of medium-chain fatty acids, namely lauric acid (C₁₂), tridecanoic acid (C₁₃), and myristic acid (C₁₄), as electrolyte additives in 1 M ZnSO₄. They are used to mitigate side reactions at the zinc anode, combining a Zn²⁺-coordinating carboxylate head group with a self-assembling hydrophobic alkyl tail. Dissolved as sodium salts to overcome the inherent aqueous solubility limitations of fatty acids, these additives suppress parasitic side reactions while maintaining facile Zn²⁺ transport. Among the additives tested, C₁₂ provided the most stable symmetric-cell cycling and lowest overpotential, while C₁₄ offered the best full-cell capacity retention, underscoring that additive selection should be guided by the intended application and evaluation metric rather than by a single universal “best” additive. The poor performance of the odd-chain C₁₃ system further indicates a proposed odd-chain packing parity effect as a critical and previously overlooked design parameter. Our findings show that fatty acids are a well-suited tunable additive for stabilizing zinc anodes.

Vibrio natriegens is a promising biotechnological chassis distinguished by exceptionally rapid growth and dynamic metabolism. This microorganism can deliver electrons both directly to electrodes via the well-established MtrCAB electron export system, as well as mediated through redox shuttle molecules. Notably, mediated electron transfer (MET) results in higher currents. Bioelectrochemical systems offer a possibility to influence the metabolic product spectrum of V. natriegens by using a poised anode as terminal electron acceptor. This study systematically evaluated twelve mediators spanning a redox potential window from −520 to +490 mV versus Ag/AgCl (3 M KCl) to establish efficient MET in V. natriegens. Among the tested compounds, potassium ferricyanide yielded the highest current densities (104 ± 20 µA cm⁻²) and faradaic efficiency. Interestingly, riboflavin underwent less than 0.05 cycles of shuttling, indicating a low electron shuttling capability. In contrast, phenazines demonstrated efficiency for electron uptake from V. natriegens cells, but the current production was unstable. Overall, a specific redox potential window above −220 mV versus Ag/AgCl was identified within which mediator reduction occurred most efficiently. These findings establish a catalog of compatible redox shuttles and lay the basis for increased efficiency of bioelectrochemical processes leveraging V. natriegens.

All-solid-state batteries (ASSBs) with sulfide electrolytes promise safer, high-energy storage, yet practical deployment increasingly depends on high-loading composite cathodes where microstructure-driven transport limitations and cathode–electrolyte interphase growth dominate performance. Here, we quantify how catholyte particle size, under solvent-free dry processing, governs cathode architecture and full-cell behavior in sulfide ASSBs employing a Si anode and NMC811 composite cathode with Li₆PS₅Cl (LPSCl) solid-state electrolyte. By systematically tuning LPSCl particle size (d50 ≈ nano–5 µm) while holding cathode composition and mass loading constant, we isolate a fundamental trade-off between interfacial contact area and microstructural uniformity. A nano catholyte delivers the highest initial capacity and rate capability, but severe catholyte clustering produces a heterogeneous composite that accelerates interfacial impedance growth, suppresses apparent lithium transport at high states of charge, and triggers rapid capacity decay and premature failure. In contrast, an intermediate 2–3 µm catholyte forms a dense, homogeneous microstructure with stable ionic pathways, yielding the most stable impedance evolution and superior durability (92.6% capacity retention over 100 cycles). Coarser 3–5 µm catholyte increases void formation and reduces contact, limiting capacity with only moderate stability. Correlating cross-sectional focused ion beam–scanning electron microscopy with electrochemical impedance spectroscopy/distribution of relaxation time and galvanostatic intermittent titration technique establishes a mechanistic framework linking catholyte size to packing, transport homogeneity, and interphase growth, providing actionable design rules for durable, high-energy dry-processed sulfide ASSBs.

The electrochemical conversion of CO₂ into energy carriers or value-added chemicals is of great significance for efficiently recycling CO₂ and mitigating its greenhouse effect. Formic acid is among the most attractive CO₂ electroreduction products. It can be obtained with high selectivity on catalysts based on non-toxic and abundant metals, such as tin and bismuth. An important issue with these electrode materials is the low current density achieved on flat surfaces. In this study, we present an electrodeposition strategy for the preparation of Sn foam electrodes with dendritic architecture, high surface area, and enhanced activity for formic acid production. A design-of-experiments approach was used to define the optimal deposition conditions on Cu support. The optimized electrodes showed excellent performance in both potentiostatic and galvanostatic electrolyses, exhibiting high Faradaic efficiencies and productivities for formic acid. The best results were obtained at E_app = −1.20 V versus RHE in potentiostatic conditions and J_app = 35 mA cm⁻² under galvanostatic control. Long-term electrolysis tests showed good stability of the electrocatalyst, which maintained a stable high current density. Interestingly, these tests evidenced an unprecedented negative effect related to the accumulation of formic acid in the catholyte.