ChemElectroChem最新文献

This study presents a comprehensive computational framework for reproducing the full X-ray absorption fine structure (XAFS) through quantum-chemical simulations. The near-edge region is accurately captured using an efficient implementation of time-dependent density-functional perturbation theory applied to core excitations, while ab initio molecular dynamics provides essential sampling of core-excitation energies and interatomic distance distributions for interpreting extended X-ray absorption fine structure (EXAFS) features. Owing to the efficiency of the approach, the total spectrum can be decomposed into contributions from bulk, defective, and surface environments, which commonly coexist in experimental systems. The methodology is demonstrated for sodium at the Na K-edge in NaCl, where the predicted spectra show good agreement with experimental measurements on thin-film samples. This strategy offers a practical route to generating chemically specific XAFS cross-section data for elements and species that remain challenging to characterize experimentally, thereby enabling deeper insights into materials of technological importance.

Bulk electrochemical phase transformations (EPTs) govern the operation of many modern electrochemical systems, from batteries to electrocatalysts. These EPTs involve a coupled interplay of ion transport from a liquid into an electrode film, electron transfer, and phase transformations in the film. Yet, despite their importance, a unified thermodynamic and kinetic understanding of EPTs remains lacking. Grounded in the theory of phase transitions and mixtures, this mini-review introduces, for the first time, a general thermodynamic framework that classifies EPTs into three main categories: regular solutions, Fickian diffusion, and spinodal decomposition. It highlights how galvanostatic charge–discharge and cyclic voltammetry modeling can elucidate reaction mechanisms using prototypical examples from electrochemical ion insertion systems such as Ni(OH)₂, MnO₂, and LiFePO₄. The concepts presented here provide a unifying foundation for interpreting solid-to-solid EPTs across mesoscopic and macroscopic scales and inspire new strategies for diagnosing and designing high-performance energy materials.

Water splitting is one of the most efficient approaches to clean hydrogen production. Assessing electrolyzer performance requires evaluating the efficiency of electrocatalysts. Herein, a motion-based method is presented that combines bipolar electrochemistry (BE) with dynamic, chemically induced electromagnets to probe the electrocatalytic efficiency of water splitting. With this approach, redox reactions are triggered in a wireless way at both extremities of a solenoid-shaped electrolyzer composed by different metal catalysts. The resulting current follows the helical coil, producing a concentrated magnetic field that drives rotational motion in the presence of an external magnetic field without traditional ferromagnetic materials. A direct correlation between the angular velocity and the catalyst efficiency is obtained. Furthermore, by applying an alternating electric field, the resulting device behaves as a direction-sensitive dynamic electrolyzer, with its angular velocity determined by which catalyst serves as the anode or cathode, respectively. This strategy provides a simple, wireless readout for catalyst screening, offering a new tool for hydrogen generation research.

Zinc-based aqueous redox flow batteries (RFBs) are emerging as promising next-generation energy storage devices based on the high theoretical capacity, abundance, and low cost of zinc. However, the universal application of zinc-based aqueous RFBs is impeded due to the dendrite formation and corrosion of zinc anodes. Here, a comprehensive overview of dendrite-suppressing strategies based on electrolyte additives is provided, systematically classified into organic and inorganic types. Particular attention is given to the working mechanisms of these additives in electrolytes to clearly define the role and basic principles. In addition, the electrochemical characteristics of strategies using various additives are compared in electrolytes and the remaining challenges facing zinc-based aqueous RFBs in the future.

Carbon-based microelectrodes are extensively used for sensing applications and space-resolved electrochemistry experiments like scanning electrochemical microscopy (SECM). For the later, needle-type disk microelectrodes, having a thin layer of insulator around the conductive disk, are of great interest due to their mass transport characteristics and small dimensions, allowing them to be brought to close proximity of the substrate. Existing fabrication methods for carbon microelectrodes use carbon fibers or the deposition of pyrolytic carbon, which can limit the possible radii of the fabricated microelectrodes and reproducibility. A simple method is presented for fabricating needle-type carbon-disk microelectrodes using conductive thermoplastic filaments that are usually employed for 3D printing. Using the heat of a candle to melt the thermoplastic inside micro and nanopipettes, microelectrodes with radii smaller than 30 µm are fabricated. Through experiments, the electrodic surface is revealed to be partially blocked, with a complex relation between the size and interspacing of the conductive sites. Simulations clarify the surface properties and demonstrate the suitability of these electrodes for SECM. As a proof-of-concept, the carbon surface is evaluated for sensing, showing that the low capacitance of the electrodes and carbon surface can be used for dopamine sensing and voltammetric pH measurements.

Conversion of glycerol to value-added products is an attractive solution to the oversupply of this byproduct of biofuel production. The glycerol oxidation reaction (GOR) may form product mixtures derived from the scission of the three-carbon (C3) glycerol backbone, generating one- (C1) or two-carbon (C2) species. Here, the bulk and flow electrolysis (FE) of the 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO)-mediated GOR reaction is explored to produce a valorized C3 product, highlighting key selectivity differences between the two methods despite using the same optimized electrolyte composition. Increasing the pH of the solution dramatically increases GOR activity but presents a tradeoff with the stability of TEMPO. At an optimal pH of 10.6 in carbonate buffer in a batch reactor, the reaction proceeds with higher than 90% yield via a 10-electron oxidation to mesoxalic acid, a C3 product. FE at much lower Reynolds number yields significantly lower selectivity toward C3, demonstrating a high sensitivity to mass transport. The work sheds light on the opportunities toward selectively producing C3 products from GOR as well as the importance of mass transfer considerations for the valorization of this key bio-feedstock and for others involving mediated electrocatalysis.

A key challenge in using scanning electrochemical microscopy (SECM) in feedback mode for corrosion studies is decoupling the redox mediator's (RM) influence from the intrinsic reactivity of the substrate. In this work, macro- and microelectrochemical experiments are combined with finite element modeling to investigate how two widely used RMs, ferrocenemethanol (FcMeOH) and hexaammineruthenium (III) chloride ( $$), affect the corrosion behavior and SECM response of iron and stainless steel (SS-316L). The apparent rate constants extracted from SECM measurements highlight a clear dependence on substrate passivation. SECM measurements over iron revealed that the applied potential required to induce FcMeOH oxidation causes ultramicroelectrode fouling via iron oxide deposition, thereby compromising measurement reliability. In contrast, $$ undergoes reduction at the active Fe surface, leading to local RM depletion and a feedback response characterized by a steeper current decay than typically observed over passive surfaces. On SS-316L, negative feedback was observed for both mediators, reflecting the presence of a stable passive film. This study identifies key pitfalls in SECM corrosion analysis and demonstrates how RM–substrate interactions can affect interpretation. These findings offer practical guidance for improving the quantitative reliability of SECM in probing localized corrosion processes of ferrous alloys.

A sustainable alternative to fossil-based energy sources is green hydrogen, which is produced by electrolysis, but the high energy demand of the oxygen evolution reaction (OER) limits its overall efficiency. Recent efforts aim to replace OER with low-potential anode reactions, such as the electro-oxidative dehydrogenation (EOD) of aldehydes, which simultaneously yield valuable chemical products. However, the mechanistic understanding of the EOD and the influence of catalyst structure and reaction conditions on selectivity and efficiency remain limited. Here, it is shown that the EOD of aldehydes on modified copper foam electrodes is strongly affected by electrode morphology, substrate concentration and structure, as well as electrolyte composition. It is demonstrated that increasing the electrochemically active surface area enhances current density up to a morphological diffusion limit reaching 110 mA cm⁻² at 0.3 V versus reversible hydrogen electrode (RHE). Higher furfural concentrations increase current density but simultaneously promote the non-faradaic Cannizzaro reaction, thereby reducing faradaic efficiency. Lower KOH concentrations partially suppress this side reaction, though 1 M remains optimal for EOD. Substrate screening reveals that electron-rich aldehydes impede the reaction, likely by hindering intermediate formation. The findings highlight the importance of the electrode morphology and the critical balance between substrate availability and parasitic side reactions in aldehyde EOD, offering practical guidelines for catalyst design and process optimization for low-potential hydrogen production.

The cover artwork depicts the electrochemical capture of concerted ion, electron, and atom motions during the galvanic replacement reaction (GRR) of silver by gold in silver nanoparticles. A mathematical model based on autocatalytic networks and cascade mechanisms explains the GRR output signal, which is the time- and concentration-dependent open-circuit potential. The model provides access to the kinetic parameters that describe the dynamics of this three-by-one galvanic exchange event. More information can be found in the Research Article by Yaovi Holade and Bonito Aristide Karamoko (DOI: 10.1002/celc.202500338).

The selection of an effective anode material is a core component in the development of sodium-ion batteries (NIBs) as an achievable alternative to lithium-ion batteries. The foremost considerations include cost-effectiveness, availability, sustainability, and the physicochemical properties required for sodium-ion storage. Biomass-derived hard carbon is among the most promising anode materials due to its favorable structural characteristics, high sodium storage capacity, and low cost of raw material sourcing. However, the main limitations of hard carbon anodes remain restricted by their low initial Coulombic efficiency (ICE) and specific capacity. Herein, corncob-derived hard carbon anodes are synthesized using a two-step process involving hydrothermal carbonization and high-temperature annealing at 1000, 1250, and 1500 °C. The structural and electrochemical properties of the resulting materials are systematically investigated using multiple characterization techniques. Electrochemical characterization demonstrates that the hard carbon annealed at 1500 °C exhibits the highest reversible capacity of 319 mAh g⁻¹ at a C/20 rate, along with an ICE of 89%, attributed to optimized porosity, improved structural order and reduced defect density. These findings highlight the potential of corncob-derived hard carbon as a sustainable and efficient anode material for next-generation NIBs.