Mapping current high-entropy materials for water electrolysis: from noble metal to transition metal

Abstract

Scaling up green hydrogen production from water electrolysis has been recognized as the most effective method to achieve energy sustainability and a carbon-neutral future, in which advanced materials hold the key to high energy conversion efficiency. High-entropy materials (HEMs), containing five or more near equimolar elements, have been in the spotlight as emerging catalysts due to their compositional, structural and functional advantages. Herein, a comprehensive overview of HEMs for catalyzing hydrogen and oxygen evolution reactions (HER and OER) is provided. This review begins with the structures, features of HEMs and the basic principles of electrocatalytic HER and OER, providing the fundamental knowledge and guiding the understanding towards the design concept of HEM catalysts. This review will give a global map of HEMs based on metal entities from noble metals to low cost transition metals, covering the alloys, oxides, phosphides, sulfides and others. Additionally, the rational design, synthetic method, catalytic properties and mechanism investigation have been discussed focusing on the structure–property relationship from experimental and theoretical views. Eventually, the remaining challenges and future development directions have been put forward. This review will provide meaningful guidance to researchers for the exploration of advanced HEMs for water splitting and the disclosure of the underlying mechanism, thus promoting the development.