The potential of high-entropy alloys as catalyst materials in water-splitting application

High-entropy alloys (HEAs), which are characterized by the inclusion of five or more elements in nearly equiatomic configurations, have garnered increasing attention due to their distinct characteristics, including exceptional physical strength, superior corrosion resistance, outstanding microhardness, and long-lasting durability. The existence of multi-constituent elements in HEAs opens up unique possibilities for the development of compatible and innovative electrocatalytic active sites. Through careful selection of elements in terms of their combination and proportions, these electrocatalytic active sites demonstrate the potential of fine-tuning for numerous technical goals. Current studies have demonstrated the promising activities of HEAs into electrocatalytic areas. However, further enhancements in their activity explore interactions among component elements and require a deeper understanding of electrocatalytic active sites, as well as a deeper comprehension of the underlying electrocatalytic mechanisms. This review aims to provide an analysis of the four core characteristics (the high-entropy effect, the severe lattice distortion effect, the sluggish diffusion effect, and the cocktail effect) associated with electrocatalysts based on HEAs. Additionally, we delve into the various applications of HEAs related to electrochemical energy transformation reactions, which encompass both the hydrogen evolution and oxygen evolution reactions. The purpose of the review is to unravel the inherent complexities associated with electrocatalytic active sites, the interactions among component elements, and the mechanisms governing reactions in HEAs. Lastly, we highlight the urgent challenges and stress the importance of theoretical and experimental research, along with the underlying raison d’être of HEAs in electrocatalysis for supplying future energy needs. It is our expectation that this review will inspire additional investigation and advancement of HEAs in relevant electrocatalysis applications, particularly in the context of water splitting processes. • Delivers design strategies for advanced HER and OER electrocatalysts. • Summarizes latest research progress of HEAs as electrocatalysts applied in water splitting. • Proposes current challenges and limitations of HEAs in electrocatalysis. • Highlights emerging research directions and recommendations of HEAs for the future development trend.