A Review and Perspective on Electrocatalysts Containing Cr for Alkaline Water Electrolysis: Hydrogen Evolution Reaction

Abstract

Transition metal-based catalysts are the next most efficient catalysts for hydrogen generation in alkaline media, after Pt-group metal catalysts. Research employing transition metal-based catalysts has progressed exponentially in recent years, resulting in catalysts with excellent activity and stability. Compared to other neighbour d-metals (Ni, Fe, Co, Cu) which receive proper preference, research on Zn, Mn, and Cr containing electrocatalysts for water electrolysis is limited. Chromium in general has received limited consideration but has begun to attract the attention of researchers in the past few years. This review provides a brief discussion and evaluation of different catalysts (oxides, hydroxides, nitrides, phosphides, sulphides, carbides, etc.) incorporating different phases of the Cr component, together with a perspective on the catalytic significance of using Cr as a co-catalyst for hydrogen evolution in alkaline media. With advancements in catalysis research, electroactivity and stability showcased by Cr-based catalysts, some even competitive against precious metal catalysts, can be lucrative solutions for H2 generation.