Transition metal phosphides as noble-metal-alternative co-catalysts for solar hydrogen production

Hydrogen (H 2 ) emerges as a highly promising contender for replacing conventional fossil fuels due to its high combustion heat value and net-zero greenhouse gas emission. Photocatalytic H 2 generation through semiconductor-based water splitting represents a clean and sustainable technology in the field. Developing highly efficient and abundant source semiconductor materials, along with co-catalysts, is paramount in achieving the industrial-level H 2 evolution by photocatalysis technology. In recent years, transition-metal phosphides (TMPs) have emerged as powerful co-catalysts for photocatalytic reactions due to their cost-effectiveness, abundant reserves in the earth's crust, and favorable physicochemical properties, thus offering a viable alternative to conventional precious metal materials. In this review, we first provide a concise historical overview and outline the structure of TMPs. The synthetic strategies of TMPs are subsequently systematically analyzed based on diverse phosphorus sources. Additionally, this review provides a comprehensive summary of the recent research endeavors conducted on TMPs as potential photocatalytic co-catalysts for efficient hydrogen generation through photocatalysis. Eventually, this review briefly addresses the prevailing key concerns, proposed countermeasures, and forthcoming challenges associated with enhancing the efficiency of photocatalytic H 2 evolution in TMPs. • Applications of TMP materials in photocatalytic H 2 production fields were reviewed. • Synthetic approach of TMP materials were summarized based on distinct phosphorus sources. • The related mechanisms during reaction process of TMP materials were discussed. • Challenges and prospect of TMP materials toward photocatalytic H 2 evolution were presented.