High entropy materials—emerging nanomaterials for electrocatalysis

Abstract

In recent years, high entropy nanomaterials (HEMs) have become a rapidly developing research field. Due to their multi-element composition and unique high entropy state, HEMs produce four typical effects (high entropy effect, sluggish diffusion, severe lattice distortion and the so-called cocktail effect) that lead to adjustable activity and enhanced stability. These HEMs have received a great deal of attention in catalyst design and exploration. However, this great potential also comes with great challenges, which is called the coexistence of opportunity and crisis. The challenges arise from their broad element composition and complex atomic arrangement configurations, which prevent the thorough and detailed study of HEMs synthesis and their inherent mechanism understanding. Due to the introduction of anions, high entropy compounds usually have more complex high configurational entropy relative to high entropy alloys, which can provide unexpected properties conducive to a wide range of applications in catalysis. Herein, we review the synthesis, structural design and electrocatalytic applications of HEMs electrocatalytic materials in recent years. Firstly, the development and the advanced characterization methods of HEMs are reviewed. Then, the superior properties of the HEMs due to their multi-element properties are discussed in different electrocatalysis applications including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), carbon dioxide reduction reaction (CO₂RR) and alcohol oxidation. Finally, we point out the existing challenges and propose solutions to these challenges in order to promote the development of HEMs in the field of electrocatalysis.