High-Entropy Alloys and Oxides as Catalysts for Water-Splitting: Synthesis, Characterization, Applications and Prospect

High-entropy materials (HEMs), due to their exceptional physicochemical performance, which includes a unique electronic structure, outstanding catalytic performance, and remarkable electrochemical stability, are considered as promising catalysts for applications such as water-splitting and fuel cells, underscoring their potential in electrocatalysis. Given the significant potential of development and promising future of applications for HEMs as electrocatalysts, research in this field is rapidly expanding. However, despite numerous innovative advancements, comprehensive summaries on HEMs as electrocatalysts still lacking. This review summarizes the synthesis, characterization, and applications of HEMs in electrocatalysis. We discussed the synthesis of high-entropy catalysts from three perspectives: dry synthesis, wet synthesis, and rapid energy-based synthesis. Subsequently, the employment of advanced characterization techniques is discussed, along with electronic structure analysis and DFT calculations, to evaluate the high-entropy catalysts. Additionally, we summarized the exploration of the applications of these catalysts in electrocatalysis, focusing primarily on hydrogen evolution, oxygen evolution, and oxygen reduction. Finally, we provided a summary of the review's contents and present insights on mechanism research, material synthesis, applications, and future development prospects, with the goal of offering valuable suggestions for the future synthesis and applications of these.