A review of noble metal-free high entropy alloys for water splitting applications

Abstract

Nano-sized high entropy alloy (HEA) catalysts have attracted much attention as extraordinary electrocatalysts in water-splitting applications, i.e., the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Recently, there has been heightened interest in metal-free HEA catalysts, which are often considered more sustainable than their noble metal counterparts, while still performing competitively. Therefore, updating the current progress of the state-of-the-art electrolysis of HEAs is essential. This review aims to summarize the recent research progress of noble metal-free HEA nanocatalysts and their performances in the HER and OER. The critical concepts of HEAs, recently reported preparation methods and their performances in water-splitting are focused on in this review. This review also provides a perspective on the existing limitations of HEAs and an outlook for research into noble metal-free HEA nanocatalysts for the HER and OER.