A Review of Transition Metal Phosphides for Hydrazine-Assisted Electrolytic Water Splitting for Hydrogen Production

Electrochemical water splitting for hydrogen production is an important path for the preparation of green hydrogen. However, the sluggish kinetics and high energy consumption of the anode oxygen evolution reaction (OER) have restricted its development. The hydrazine oxidation reaction (HzOR), with its low theoretical potential, fast kinetics, clean products, and the ability to simultaneously treat hydrazine-containing wastewater, has emerged as an ideal anode reaction to replace OER. Transition metal phosphides (TMPs) have shown noble-metal-like activity in HzOR catalysis due to their tunable d-band electronic structure, abundant active sites, high conductivity, and structural stability, making them highly promising non-noble metal catalysts. However, most existing reviews focus on the catalytic performance of TMPs in general hydrogen evolution reaction (HER)/OER systems or merely briefly mention HzOR as one of many anode reactions. Therefore, this review aims to comprehensively and systematically elaborate on the design strategies of TMPs catalysts for hydrazine-assisted electrolytic water splitting for hydrogen production and their applications in HzOR, deeply discuss the current progress, challenges, and future directions, and provide references for the development and industrial application of low-cost, high-efficiency, and high-stability hydrazine-assisted hydrogen production catalysts.