High-entropy materials for electrocatalysis: Fundamentals, design, and applications in OER/ORR

High-entropy materials (HEMs) are recently emerging as a promising new class of high-performance electrocatalysts for energy conversion due to their tunable compositions, multicomponent synergistic effects, high intrinsic properties, diverse active sites, large surface areas, optimized electronic structures, high adsorption strengths, resulting in high activities, excellent selectivity's, and exceptional stability. Despite numerous innovative advancements, complete and extensive reviews describing the functions, characteristics, and mechanisms as electrocatalysts are currently lacking. Accordingly, this review summarizes the historical background, types, fundamental properties, evolving synthesis techniques, physical characteristics, theoretical aspects, and catalytic capabilities of HEM-based catalysts for application in oxygen evolution reaction (OER)/oxygen reduction reaction (ORR). Additionally, it explores the importance of modifying fabrication conditions, intermetallic behaviors, morphologies, kinetic parameters, and post-reaction surface electronic structures. Addressing knowledge gaps through the analysis of existing studies, this review initially establishes the substantial advantages of HEMs in terms of catalyst design, characterization, reaction mechanisms, performance enhancement, and stability.