ChemElectroChem最新文献

Herein, the physical modeling of dynamic electrochemical impedance spectroscopy using the example of a redox couple in solution is investigated. While the study of electrochemical systems during operation is of great interest, one is always confronted with challenges due to nonlinearities when exciting the system with both a cyclic voltammetry (CV) and a multisine. A two-component model is proposed, which first solves for the CV and then calculates the effect of the multisine by means of linearization around the CV of all the variables. Three models are tested: a dynamic transfer function model, a stationary transfer function model, and a quadrature band-pass filter model. The obtained impedance spectra are fitted using the regression analysis with Padé approximants and equivalent circuits. The results show that the dynamic transfer function model is very close to the experimental practice of obtaining dynamic impedance spectra through quadrature filters, and that stationarity has a significant effect on the impedance spectra in the low-frequency range.

Carbon materials are promising to fulfill the worldwide need for advanced materials in many areas, particularly in electrochemical applications. However, achieving both high conductivity and surface functionalization in carbon electrodes remains a significant challenge. Herein, a scalable, sustainable, binder-free carbon disc electrode is developed in the desired size and shape. Subsequent femtosecond laser treatment introduces surface functionalization with pyrrolic and pyridinic nitrogen species (up to 12.6 at%, as determined by X-ray photoelectron spectroscopy) while preserving the bulk crystallinity and conductivity of the electrode. The laser-treated surfaces exhibit superhydrophilicity (water contact angle of 0°) and oleophilicity (0° for n-heptane, 25° for n-heptadecane), enabling enhanced interaction with electrolytes and anchoring of metal species like iron ions. Electrochemical impedance spectroscopy confirms minimal resistance (≤10 Ω) in 0.1M KOH, even after functionalization. The functionalized electrodes demonstrate improved stability in oxygen evolution reaction tests, with laser-treated samples showing 300–500 mV higher activity than untreated counterparts when Fe-impregnated. This work establishes a simple, industrial-scale method for creating multifunctional carbon electrodes with tailored surface properties, bridging the gap between material sustainability and electrochemical performance.

Silicon-carbon (Si/C) composites are extensively studied as anode materials for lithium-ion batteries (LIBs), with carbon typically sourced from biomass precursors or petroleum byproducts to produce amorphous and graphitic carbon, respectively. However, the use of iron salt as an “activator” to induce graphitization in combination with silicon remains unexplored. In this study, biomass-derived carbon is graphitized using an Fe salt activator to evaluate its effectiveness as a silicon coating for high-capacity anodes. Structural analysis via X-ray diffraction, Raman spectroscopy, and transmission electron microscopy reveals the formation of graphite, predominantly in the form of carbon nanotubes. Electrochemical performance is assessed in both half-cell and full-cell configurations, demonstrating the presence of “activated” graphite enhances reversible capacity, electronic conductivity, and cycle life. These findings highlight low-temperature Fe-assisted graphitization of biomass-derivedcarbon as a promising approach for developing high-performance LIB anodes.

The use of earth-abundant materials for novel electrodes for solar-driven electrolysis will play a significant role in the future production of hydrogen as a green energy source. The choice of electrolyte will play a major role in how efficient and stable future photoelectrochemical cells (PEC) operate. A new approach to determining PEC efficiency using broadband acoustic resonance dissolution spectroscopy (BARDS) is investigated to analyze the real-time production of hydrogen and oxygen at platinum electrodes in different electrolyte solutions. The parameters investigated include concentration of electrolyte, surface area of the electrode, and the potential applied to the cell. Herein, the suitability of neutral buffer as an electrolyte on a par with either acid or basic electrolytes is shown. This finding allows for the potential design of solar to hydrogen electrolysers which can operate under mild, neutral, and stable conditions using earth-abundant materials for hydrogen production. It is also shown how BARDS can readily visualize and track gas evolution in real-time and in situ in an open system without the need for gas collection. It is anticipated that the technique can be utilized in the future evaluation of newly developed electrode materials in terms of efficiency, stability, and life span.

Hard carbon is the most widely applied material for sodium-ion battery negative electrodes. Although capacities comparable to those of lithium/graphite can be achieved, the underlying sodium storage mechanisms remain poorly understood. From a simplified perspective, a two-step process is commonly observed: first, sodium adsorbs to the polar sites of the carbon (“sloping region”) and then fills the small voids in the material (“plateau region”). In order to study the impact of the molecular size of precursors on the microstructure of carbon materials and their pore geometry, a systematic series of cyclodextrin-based hard carbons has been synthesized. It is found that the type of precursors used influences the resulting materials’ pore structure, which at higher temperatures can be converted to a closed pore system. This pore conversion enables a large, low-potential sodiation plateau. Indeed, up to 75% of the total capacity is measured at potentials below 0.1 V versus Na⁺/Na. Additionally, the plateau region can be extended by up to 16% by additionally considering reversible capacity below 0 V versus Na⁺/Na, which means quasimetallic sodium can be stabilized within such structural motifs. Finally, gas physisorption measurements are related to charge–discharge data to identify the architecture of pores relevant to energy storage.

Electrode material selection and structural designs of electrochemical chips are fundamental parameters in the field of electrochemical sensing. These parameters directly affect sensor conductivity, selectivity, stability, surface area, and overall performance. This article summarizes the most common electrode architectures and commercially available materials currently used in the development of electrochemical sensors, including carbon-based materials (e.g., boron-doped diamond, graphite, graphene, glassy carbon, carbon nanotubes, and carbon fibers), metal-based materials and alloys (e.g., gold, platinum, silver, nickel, and metal oxides), conductive polymers (e.g., polyaniline, polypyrrole, and poly(3,4-ethylenedioxythiophene)), and redox dyes and mediators (Prussian blue, Meldola blue, etc.). It highlights the advantages of each category and identifies suitable electrode materials for specific target analytes. Finally, this review aims to guide readers in selecting appropriate electrode materials and designs tailored to a specific application.

Electrochemical processes are of particular interest in modern chemical technologies as they have numerous advantages over classical approaches. While computational support for investigating thermochemical reaction mechanisms is well established, there is still no consistent methodology for modeling electrochemical processes beyond the computational hydrogen electrode. This work addresses this gap through the study of the Shono-type oxidation of N-formylpyrrolidine. Combining density functional theory calculations, the concept of computational Fc⁺/Fc electrode, Marcus–Hush approach, and Butler–Volmer model, the reaction mechanism is elucidated, including the identification of the role and position of proton-coupled electron transfer process. Additionally, simulated cyclic voltammograms are in excellent agreement with experimental studies performed in parallel.

Accurate free-energy landscapes are essential for understanding electrocatalytic processes, especially those involving proton–coupled electron transfer. While density functional theory (DFT) is widely used to model such reactions, it often introduces significant errors in the computed free energies of gas-phase reference molecules, leading to inconsistencies in the derivation of the free-energy changes of the elementary reaction steps. This study presents and compares different correction schemes to address gas-phase DFT errors. Unlike conventional methods that rely on bond–order–based adjustments, this approach reconstructs the formation free energy of target molecules as a linear combination of theoretically determined formation free energies of carefully selected reference molecules. This framework ensures consistency across the reaction network while avoiding dependence on the bond order. This methodology applies to the nitrogen reduction reaction on Mo₂C(0001) MXene using dispersion–corrected DFT calculations. The incorporation of gas-phase corrections significantly reshapes the free-energy profile and alters catalytic activity descriptors, including the largest free-energy span of the G_max(U) descriptor. Findings highlight the importance of thermodynamic accuracy in computational electrocatalysis and provide a generalizable framework that improves the reliability of DFT-based predictions across a wide range of electrochemical systems for energy conversion and storage.

Among the various approaches for hydrogen production, electrocatalytic water splitting for hydrogen evolution reaction (HER) is considered as the most promising technology for industrial application. However, the large-scale implementation of this technology is still hindered by its dependence on expensive noble metal-based catalysts. Transition metal dichalcogenides (TMDs), owing to their layered structures and tunable electronic properties, have emerged as promising alternatives to noble metals for HER. Nevertheless, the intrinsic catalytic performance of TMDs remains inferior to that of noble metals, making the development of efficient and stable TMD-based electrocatalysts essential for practical applications. One effective strategy to enhance the HER activity of TMDs is metal combination, whereby various metals are incorporated into TMD system. The key advantage of this approach lies in the diverse roles that different metals can play, including stabilizing crystal structure, modulating electronic structure, constructing nanostructures, and inducing synergistic effects. To inspire both theoretical and experimental researchers for further advancements, this review presents a comprehensive overview of recent progress in metal combination strategies for TMD-based HER electrocatalysts. Particular emphasis is placed on the role of metal components in both single-phase systems and heterostructures, aiming to uncover general design principles for the rational development of high-performance multimetallic electrocatalysts.

In the present study, the influence of crystallinity and synthesis method of a NiFe₂O₄ catalyst for anion exchange membrane water electrolysis (AEMWE) is systematically investigated. Catalysts are prepared using an aerosol-assisted spray-pyrolysis approach, both with and without post-calcination treatment, and a co-precipitation method. The spray-pyrolysis approach produces amorphous particles, whereas the co-precipitation and post-calcination result in partial crystallization of the particles. Notably, the post-calcinated catalyst demonstrated the highest degree of crystallinity, corresponding to reduced catalytic activity and stability. Employing the amorphous NiFe₂O₄ catalyst provides the highest activity with an iR_HF-free cell voltage of 1.565 V at 1 A cm⁻². By utilizing a Nafion instead of a PiperION ionomer the iR_HF-free cell voltage is further lowered by 37 mV. Moreover, in this configuration the cell performance remained stable, with a degradation rate of only 91 μV h⁻¹, over 200 h at 3 A cm⁻² and 80 °C with a cell voltage of just 1.8 V. These findings highlight the critical role of amorphous anode catalysts in achieving both high performance and enduring stability in AEMWE applications, suggesting pathways for future catalyst optimization.