Advances in Modification Strategies and Electrolytic Water Splitting Performance of Transition Metal Phosphide Catalysts

Abstract

Hydrogen production from electrolytic water splitting is regarded as a core route toward sustainable hydrogen supply, although the industrialization of this technology has long been constrained by the high cost of noble metal catalysts. Transition metal phosphides (TMPs) stand out as a low-cost alternative for water electrolysis, owing to their noble-metal-like electronic structures and good stability in both acidic and alkaline media. In this review, the reaction mechanisms of the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are first introduced, followed by a summary of the mainstream preparation methods for TMPs, namely liquid-phase synthesis, pyrolysis reduction, ball milling, electrodeposition, and gas–solid reaction. Four major modification strategies—interface engineering, vacancy defects, structural regulation, and elemental doping—are then discussed in detail, with emphasis on how each approach modulates the electronic structure, increases the number of active sites, and optimizes the adsorption energy of reaction intermediates. The HER, OER, and overall water splitting performances of differently modified TMPs are also compared. Despite these advances, existing TMP catalysts still face problems such as insufficient stability at high current densities and difficulty in large-scale preparation. Looking ahead, high-entropy phosphides and multi-element co-doping are considered promising directions for developing high-efficiency bifunctional electrocatalysts for water electrolysis.