Understanding the enhanced catalytic activity of high entropy alloys: from theory to experiment

Abstract

High-entropy alloys (HEAs) have evolved to be one of the most popular materials in the last decade. Their unique configuration and attractive properties make HEAs one of the most promising catalysts. Although a very limited amount of work has been reported, higher activities of HEAs than traditional catalysts have been confirmed. This review firstly summarizes the current synthetic methods of nanostructured HEA catalysts. Then, four core effects of HEAs, namely high entropy, cocktail effect, lattice distortion and sluggish diffusion, are briefly introduced, and their impacts on the catalytic properties of HEAs are highlighted. The research progress in the application of HEAs in heterogeneous catalysis is subsequently reviewed from the perspectives of both theory and experiment. The relationships among metastable microstructures, substitution effects (i.e. strain, ligand and ensemble effects) and d-band center are discussed in detail, and their impacts on the adsorption energy of intermediates in catalytic reactions are emphasized. We conclude the review with the discussion of the challenges and opportunities of HEA catalysts. Several directions of future HEA research are put forward. The review provides a valuable resource for those interested in these exciting catalytic materials.