Nanoscale high-entropy alloy for electrocatalysis

High-entropy alloys (HEAs) are a new kind of alloy with five or more alloy elements at equal or near-equal ratios. The tunable multicomponent structure and potential novel properties of HEAs have attracted widespread attention. Benefiting from advances in synthesis technology, nanoscale HEAs were acquired successfully, the high specific surface area and quantum size effect of which further improved their capacity for catalysis. Nevertheless, the complex composition of elements makes it challenging to clarify the atomic structure of HEAs, and their catalytic studies are still in their infancy. A comprehensive review summarizing the current understanding of the structure of HEAs and their catalytic performance is urgently needed. This review first presents basic insights into HEAs, including concept definition, structural features, and progressive synthesis and characterization technologies. Then, the electrocatalytic performance of HEAs is discussed based on the structural diversity and synergistic role of each component element. Considering the limitation of trial-and-error methods in dealing with this complex system, high-throughput screening technologies are also introduced. This review aims to promote the understanding of HEAs and therefore achieve the design of high-efficiency catalysts relying on HEAs.