ChemElectroChem最新文献

This article systematically reviews the progress in oxygen evolution reaction (OER) electrocatalysts in acidic media. It first analyzes the adsorbate evolution mechanism and the lattice oxygen mechanism (LOM), noting that although LOM has a lower reaction energy barrier, it is less stable. The article then reviews the latest advancements in noble, non-noble metal, and carbide catalysts, emphasizing the importance of optimizing surface and electronic structures to enhance catalytic performance. Finally, the article summarizes the innovative pathways of acidic OER catalysts. More details can be found in the Review by Jie Yin, Gege Su, and Jiayi Yang (DOI: 10.1002/celc.202400559).

A composite photocatalyst with a hierarchical heterostructure consisting of 1-D cobalt oxide nanoneedles and Cu@2-D graphene core-shell nanoparticles makes the photocatalytic CO₂ reduction a promising future for substantial energy. More details can be found in the Research Article by Chuan-Pei Lee and co-workers (DOI: 10.1002/celc.202400689).

Anion redox reactions can considerably enhance battery capacity; however, they face challenges, such as phase separation and slow kinetics due to large structural changes. In crystalline oxide materials, phase separation of the anionic component is governed by the positional relationship between the energy levels of the orbitals of the anionic component and unoccupied orbitals of the constituent transition metals. However, in addition to these elemental parameters, structural constraints are important for crystalline materials. Previously, we reported that the slow kinetics of the anion redox reactions in Na₃FeS₃ can be improved through amorphization, which increases the structural degrees of freedom. In this study, we examined amorphous Na₃CoS₃, in which the Fe in Na₃FeS₃ was replaced by Co, to investigate the transition metal dependence of the anion redox reversibility in amorphous compounds with large structural degrees of freedom. The reversibility was reduced by replacing Fe with Co owing to the phase separation caused by the sulfur multimer formation. First-principles calculations revealed that multimer formation was driven by the transfer of electrons from dimeric sulfur to the unoccupied orbital of Co. The results confirm the transition-metal selection guidelines for the reversibility of anion redox reactions, even for amorphous compounds with few structural constraints.

Developing effective electrolytes is crucial for boosting the performance of Lithium-Sulfur (LiS) rechargeable battery. Recent improvements in electrolyte formulations have enhanced cyclability by increasing electrochemical stability at the electrode interfaces. However, achieving both high ionic conductivity (σ) and stability at these interfaces simultaneously remains a significant challenge. In this study, we utilized a strategy to suppress polysulfide dissolution by employing a mixture of 1,3-dioxolane (DOL) and hydrocarbon solvents with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) electrolyte salt. Compared to the conventional electrolyte solution, which is 1 M LiTFSI salt in a 50/50 vol % mixture of DOL and dimethoxy ethane (DME), the LiTFSI electrolyte with DOL/hydrocarbon solvents demonstrate better cycling stability, compatibility with the Li-metal anode, and a high specific discharge capacity (Csp). Among the various DOL/hydrocarbon and LiTFSI electrolyte salts, the combination of DOL and n-hexane, a linear hydrocarbon, with LiTFSI electrolyte salt, (DnH40LiTFSI) exhibits remarkable σ (6.5×10⁻³ S/cm at 30 °C), compatibility with the Li-metal anode, an initial Csp of ca. 1264 mAh/g, cycling stability (Csp and Coulombic efficiency are 811 mAh/g and 98.09 % after 120 cycles) at 0.1 C by forming a good protective layer on the Li-metal surface and preventing polysulfide dissolution.

The Cu(II)-mediated Chan-Lam coupling reaction offers several benefits for developing point-of-care detection devices on microelectrode arrays. However, achieving selectivity on borate ester-based polymer surfaces has proven difficult due to background reactions. Fluorescence-based studies were conducted using fluorescently labeled acetylene nucleophiles. Initial experiments revealed significant background fluorescence across the electrode array, indicating selectivity issues. Further investigation uncovered significant background reactions occurring even without copper. To address this, a strategy utilizing an arylbromide-based polymer was developed, enhancing reaction selectivity by minimizing background non-specific reactions. Exploration into the confinement mechanism revealed the role of acetylene in forming dimers, facilitating rapid consumption of Cu(II) reagents that escaped from the specific electrodes used. These findings offer a way to construct devices for the multiplex point-of-care detection of metabolites, improving performance and accuracy in diagnostic devices.

As an emerging technology, polymer electrolyte fuel cells (PEFCs) powered by clean hydrogen can be a great source of renewable power generation with flexible utilization because of high gravimetric energy density of hydrogen. To be used in real-life applications, PEFCs need to maintain their performance for long-term use under a wide range of conditions. Therefore, it's important to understand the degradation of the PEFC under protocols that are closely related to the catalyst lifetime. Alloying Pt with transitional metal improves catalyst activity. It is also crucial to understand Pt alloys degradation mechanisms to improve their durability. To study durability of Pt alloys, accelerated stress tests (ASTs) are performed on Pt−Co catalyst supported on two types of carbon. Two different AST protocols were being studied: Membrane Electrolyte Assembly (MEA) AST based on the protocol introduced by the Million Mile Fuel Cell Truck consortium in 2023 and Catalyst AST, adopted from the U.S. Department of Energy (DoE).

Successful deployment of hydrogen technologies relies on converting electricity from renewable energy sources into hydrogen. Proton exchange membrane electrolyzers are currently the technology of choice for this transformation. These devices use electricity to split water molecules into hydrogen and oxygen. To build membrane electrode assemblies with low iridium loading, while maintaining good in-plane conductivity, an extended network of iridium oxide is required. To this effect, we synthesize IrO2 catalysts on a non-conductive titanium dioxide anatase support. The iridium oxide particles obtained are well dispersed on the surface of the support. Furthermore, at the optimal iridium oxide loading, a network of relatively small iridium oxide particles covers the surface of the support. Increasing the iridium oxide loading beyond this optimum does not bring any appreciable increase in connectivity and decreases the surface-to-mass ratio of iridium oxide, which is detrimental to the mass activity of the material. The synthesis method presented herein leads to the formation of an iridium oxide extended network that grants electrical conductivity to the material despite the high resistivity of the titanium dioxide anatase support. The result is a catalyst that enjoys the chemical stability of anatase but is also conductive and highly active for the OER.

Facing the increasingly severe challenges of energy and environment, green hydrogen production technology has attracted widespread attention. The efficient catalysis of the acidic oxygen evolution reaction (OER) has always been a technological bottleneck that needs to be overcome. This article reviews the latest research progress in this field in recent years. Firstly, the article analyzes the two classic OER reaction mechanisms, adsorbate evolution mechanism (AEM) and lattice oxygen mechanism (LOM), finds that the latter may have a lower reaction energy barrier but is less stable. This provides a theoretical basis for designing catalysts with both high activity and stability. Subsequently, the article reviews recent advancements in noble, non-noble metals, and carbides catalysts, highlighting that optimizing composition and electronic structures is crucial for enhancing catalytic performance. The article also illustrates the implementation pathways of these strategies with specific examples. These innovative designs not only significantly enhance catalytic performance but also greatly improve stability, injecting new momentum into the commercial application of green hydrogen production. In summary, this article comprehensively discusses the innovative pathways of acidic OER catalysts from mechanism exploration to case analysis, and will undoubtedly provide an important reference for further breakthroughs in this field.

While searching for ultra-safe high-power anodes for Li-ion batteries, TiNb₂O₇ (TNO) emerged as a promising material for higher energy density compared to the current state-of-the-art Li₄Ti₅O₁₂ (LTO). Here, the electrochemistry of isolated carbon coated particles of both anode materials were for the first time studied using scanning electrochemical cell microscopy (SECCM). Interestingly, stochastic current event observations were made possible because of the small electrochemical cell created by SECCM and were designated as potential-driven stochastic events (PDSEs). The PDSEs were especially prominent in TNO compared to LTO. Metrics for judging the frequency and intensity of PDSEs were developed to compare the impact of different C-rates, particle masses and sizes of SECCM landings. The frequency and/or intensity of PDSEs increases with higher C-rates and larger overpotentials. Possible theories for the PDSEs were explored, including droplet electrowetting/spreading, gas evolution, (de)lithiation mechanisms, mass transfer limitations and inter-/intra- particle cracking. We speculate that the propensity of TNO to undergo PDSEs as compared to LTO is mainly related to the fact that TNO is known to crack extensively during cycling.

The front cover illustration depicts the electrochemical behavior of various stainless-steel (SUS) grades in coin cells using electrolyte formulations containing lithium hexafluorophosphate (LiPF6) and lithium bis(fluorosulfonyl)imide (LiFSI) salts. The presence of chlorine ions (Cl-) as impurities in the LiFSI salt promotes localized corrosion, leading to pitting and dissolution of SUS when the cell voltage approaches 4.2 V. Such dissolution behavior is influenced by multiple factors, with the specific SUS grade and the presence of surface coatings playing critical roles in determining corrosion resistance. More details can be found in the Research Article by Marian Cristian Stan, Isidora Cekic-Laskovic, and co-workers (DOI:10.1002/celc.202400632.