Research Progress and Application Prospects of Transition Metal Phosphosulfide Heterojunction Catalysts in Electrocatalytic Water Splitting

In water electrolysis systems, the hydrogen evolution reaction (HER) occurs at the cathode to produce hydrogen, while the oxygen evolution reaction (OER) occurs at the anode to generate oxygen. However, in practical applications, the energy conversion efficiency is only 56%–73%, which severely restricts the large‐scale promotion of water electrolysis technology and makes water electrolysis research a hot topic in academia. In recent years, researchers have been dedicated to developing high‐performance heterojunction catalysts, among which transition metal phosphosulfide heterojunction catalysts have attracted significant attention. Such catalysts exhibit excellent performance in water splitting reactions, offering hope for breaking through the technical bottlenecks of water electrolysis. This review focuses on transition metal phosphosulfide heterojunction catalysts, systematically summarizing their advantages, synthesis methods, and optimization strategies. It deeply analyzes the catalytic mechanisms of HER and OER, as well as the characteristics of efficient catalysts, and explores the dynamic processes of catalytic reactions. Meanwhile, current challenges are summarized, and reasonable prospects for their applications in the field of electrocatalytic water splitting are proposed, aiming to provide valuable references for follow‐up research.