Well-defined nanostructures of high entropy alloys for electrocatalysis.

High-entropy alloys (HEAs) have attracted significant attention for electrocatalytic energy conversion by virtue of their promisingly high efficiency, stability, and low cost. Recently, encouraging progress has been made in tuning the structure and composition of HEAs used in electrolyzers and fuel cells. However, the understanding on the synthetic methods and the structure-property-performance relationship of well-defined HEAs nanostructures is still inadequate. To gain insight into the future research directions on HEAs for electrocatalysis, in this paper, the synthetic methods commonly used to obtain well-defined HEAs nanostructures (0D nanoparticles, 1D nanowires, 2D nanosheets/nanoplates, 3D nanoporous structures, and other three-dimensional morphologies) are first summarized. Then, the authors discuss the application of well-defined HEAs nanostructures in several typical electrocatalytic reactions, including hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, alcohol oxidation reaction, carbon dioxide reduction reaction, nitrogen reduction reaction, and formic acid oxidation reaction. Finally, a practical perspective on the future research directions on well-defined HEAs nanostructured electrocatalysts is provided.