Recent progress in alkaline electrocatalytic hydrogen oxidation reaction: Mechanisms, catalysts design and perspectives

Anion-exchange membrane fuel cells (AEMFCs) have become a focal point of research within electrochemical devices, driven by remarkable advancements in the development of cathode catalysts. A key challenge is the sluggish alkaline hydrogen oxidation reaction (HOR) in the anode, with reaction rates significantly lower than its acidic counterpart, inevitably leading to a significant increase in catalyst costs. To address this issue, researchers have recently explored novel HOR catalysts for alkaline HOR, demonstrating the booming interest in alkaline HOR catalysts and highlighting the urgency of summarizing these developments to guide future catalyst design. This review outlines crucial theoretical frameworks for alkaline HOR, specifically hydrogen binding energy (HBE) theory, bifunctional theories, and interfacial water (H₂O)-related theories. These are vital for guiding catalyst design and mechanism investigation. It provides a detailed analysis of current design strategies and recent breakthroughs in catalyst performance, revealing underlying reasons that enhance catalyst robustness and activity. The review also highlights considerations for evaluating alkaline HOR performance, emphasizes further exploring mechanisms, and developing future direction for catalyst designs. It further stresses the need for innovative approaches to deepen our understanding of reaction mechanisms and improve efficiency and sustainability in alkaline HOR technology.