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Proton Exchange Membrane Water Electrolysis (PEMWE) under acidic conditions outperforms alkaline water electrolysis in terms of less resistance loss, higher current density, and higher produced hydrogen purity, which make it more economical in long-term applications. However, the efficiency of PEMWE is severely limited by the slow kinetics of anodic oxygen evolution reaction (OER), poor catalyst stability, and high cost. Therefore, researchers in the past decade have made great efforts to explore cheap, efficient, and stable electrode materials. Among them, the RuO2 electrocatalyst has been proved to be a major promising alternative to Ir-based catalysts and the most promising OER catalyst owing to its excellent electrocatalytic activity and high pH adaptability. In this review, we elaborate two reaction mechanisms of OER (lattice oxygen mechanism and adsorbate evolution mechanism), comprehensively summarize and discuss the recently reported RuO2-based OER electrocatalysts under acidic conditions, and propose many advanced modification strategies to further improve the activity and stability of RuO2-based electrocatalytic OER. Finally, we provide suggestions for overcoming the challenges faced by RuO2 electrocatalysts in practical applications and make prospects for future research. This review provides perspectives and guidance for the rational design of highly active and stable acidic OER electrocatalysts based on PEMWE. [ABSTRACT FROM AUTHOR]

The efficiency and performance of proton exchange membrane fuel cells (PEMFCs) are primarily influenced by ORR electrocatalysts. In recent years, atomically dispersed metal–nitrogen–carbon (M-N-C) catalysts have gained significant attention due to their high active center density, high atomic utilization, and high activity. These catalysts are now considered the preferred alternative to traditional noble metal electrocatalysts. The unique properties of M-N-C catalysts are anticipated to enhance the energy conversion efficiency and lower the manufacturing cost of the entire system, thereby facilitating the commercialization and widespread application of fuel cell technology. This article initially delves into the origin of performance and degradation mechanisms of Fe-N-C catalysts from both experimental and theoretical perspectives. Building on this foundation, the focus shifts to strategies aimed at enhancing the activity and durability of atomically dispersed Fe-N-C catalysts. These strategies encompass the use of bimetallic atoms, atomic clusters, heteroatoms (B, S, and P), and morphology regulation to optimize catalytic active sites. This article concludes by detailing the current challenges and future prospects of atomically dispersed Fe-N-C catalysts. [ABSTRACT FROM AUTHOR]

The progress of proton exchange membrane fuel cells (PEMFCs) in the clean energy sector is notable for its efficiency and eco-friendliness, although challenges remain in terms of durability, cost and power density. The oxygen reduction reaction (ORR) is a key sluggish process and although current platinum-based catalysts are effective, their high cost and instability is a significant barrier. Single-atom catalysts (SACs) offer an economically viable alternative with comparable catalytic activity for ORR. The primary concern regarding SACs is their operational stability under PEMFCs conditions. In this article, we review current strategies for increasing the catalytic activity of SACs, including increasing active site density, optimizing metal center coordination through heteroatom doping, and engineering porous substrates. To enhance durability, we discuss methods to stabilize metal centers, mitigate the effects of the Fenton reaction, and improve graphitization of the carbon matrix. Future research should apply computational chemistry to predict catalyst properties, develop in situ characterization for real-time active site analysis, explore novel catalysts without the use of platinum-based catalysts to reduce dependence on rare and noble metal, and investigate the long-term stability of catalyst under operating conditions. The aim is to engineer SACs that meet and surpass the performance benchmarks of PEMFCs, contributing to a sustainable energy future. [ABSTRACT FROM AUTHOR]

As a sustainable energy form, hydrogen can be most practically obtained from electrocatalytic water splitting. The familiar organics can be oxidized to more useful intermediates in chemical industries. Herein, a SnO 2 /(CoTeO 3) 2 heterojunction is designed as an electrocatalyst for hydrogen evolution reaction (HER) and organic electrocatalytic oxidation. The heterojunction has good electrocatalytic performances with overpotentials of 281 mV at 10 mA cm−2 in 1 M KOH+0.1 M glycerol, 358 mV at 10 mA cm−2 in 1 M KOH +0.33 M urea, 203 mV in 1 M KOH+0.1 M glucose, and 111 mV for HER in 1 M KOH. The glucose is electrocatalytically oxidized to gluconic acid and formic acid. Density functional theory computation shows the formation of the SnO 2 /(CoTeO 3) 2 heterojunction makes the total densities of states of SnO 2 move to the Fermi level, which is beneficial for adsorption in the electrocatalysis. This work propagandizes a new avenue for heterojunction electrocatalyst is applied for organics oxidation linking to hydrogen production. • The SnO 2 /(CoTeO 3) 2 heterojunction is first prepared as electrocatalyst. • The SnO 2 /(CoTeO 3) 2 heterojunction shows good performances for OER, GOR, and HER. • The d-band center of SnO 2 /CoTeO 3 heterojunction is closer to the Fermi level. • Glucose is oxidized to high-value-added formic acid through the SnO 2 /(CoTeO 3) 2. [ABSTRACT FROM AUTHOR]