ChemElectroChem最新文献

The surface oxide reduction method, a well-established technique for determining the electrochemically active surface area of Pd, is also widely used for Pd–Co alloys. However, comprehensive studies investigating the influence of the alloy composition on the determination of the surface area by the surface oxide reduction method are lacking for this alloy system. To fill this gap, a systematic investigation is conducted by applying the surface oxide reduction method to homogeneous Pd_100−xCo_x alloy samples with different compositions (x = 0−20). The results reveal that full monolayer coverage with surface oxide occurs at lower potentials than for pure Pd and that the surface area determined by this method systematically decreases with increasing Co content, indicating that only the Pd sites are accessible by this method. However, it is demonstrated that by taking the alloy composition into account, the surface area of the whole alloy can also be reliably determined.

The image depicts personifications of sulfur and lithium mirroring each other’s movements to illustrate the linear correlation observed in our study. They are surrounded by molecules of the solvents used in the research. The Research Article by Ingo Krossing and co-workers explores the correlation between the potentials of lithium and sulfur as influenced by the choice of electrolyte solvent (DOI: 10.1002/celc.202500109).

To improve the chemical durability of proton exchange membrane fuel cells (PEMFCs) while imposing minimal performance penalties, the effects of simultaneously incorporating tungsten oxide (WO_x) and cerium (Ce) ions into the membrane are evaluated. Open-circuit voltage (OCV) hold tests are conducted using Nafion membranes containing Ce ions alone, WO_x alone, or both. The combination of Ce³⁺, a hydroxyl radical scavenger, and WO_x, a hydrogen peroxide decomposition catalyst with high stability and immobility under acidic conditions, achieves a degradation suppression effect that is consistent with the product of their individual contributions. The distinct mitigation mechanisms of Ce ions and WO_x are supported by ex situ H₂O₂ decomposition experiments and membrane molecular weight analysis. No marked initial performance loss is observed with WO_x addition. These results indicate that the use of WO_x allows for reduced Ce ion loading and that it mitigates negative effects associated with Ce ion mobility. The combined use of suppressants that target different degradation pathways presents a promising strategy for achieving high membrane durability with minimal performance tradeoffs.

Water electrolysis technology is a core pathway for green hydrogen production and plays a crucial role in enabling efficient storage and conversion of clean energy. Among electrolysis systems, proton exchange membrane water electrolyzers (PEMWEs) are ideal for large-scale hydrogen production due to their high current density, rapid response characteristics, and high-purity hydrogen output. However, the acidic oxygen evolution reaction (OER) at the anode remains a key bottleneck in PEMWEs cost and lifetime due to its sluggish kinetics, high overpotential, and heavy reliance on noble metal-based catalysts (Ir and Ru). Developing highly active, low-cost, and durable acidic OER electrocatalysts is essential for reducing electrolyzer energy consumption and advancing the green hydrogen economy. This review systematically examines advancements in acidic OER catalysts over the past five years, focusing on fundamental mechanistic insights, advanced low-loading noble metal-based catalysts, and progress in nonnoble metal-based catalyst design. An outlook on future directions for acidic OER research, emphasizes mechanistic studies and electrocatalyst design strategies to overcome current challenges.

Solid-state batteries (SSBs) have emerged as promising candidates for next-generation energy-storage solutions, particularly for electric vehicle applications. To overcome challenges related to interfacial stability and electro-chemo-mechanical degradation during operation, the development of protective surface coatings for cathode active materials (CAMs) is essential. Lithium-rich antiperovskites (LiRAPs) exhibit a unique set of beneficial properties, notably a high ionic partial conductivity at room temperature, enabling the deployment of advanced coating techniques via cost-effective and environmentally benign methods. In the present work, the application of LiRAP coatings to a layered Ni-rich CAM, namely LiNi_0.85Co_0.1Mn_0.05O₂ (NCM85), is examined, utilizing a low-temperature and solvent-free approach. The effectiveness of the procedure is evaluated through microscopy analyses and electrochemical performance assessments. The results demonstrate a significant improvement in cyclability, highlighting the potential of LiRAP-based surface coatings for enhancing the performance and longevity of high-capacity cathodes in SSB systems.

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.