Advanced transition metal phosphide-based materials for hydrogen evolution reactions: a comprehensive review

In recent years, phosphorous compounds have been developed as spectacular materials for various catalytic reactions in the field of electrochemistry. This review focuses on novel transition metal phosphides (TMPs) for a hydrogen evolution reaction (HER) from aqueous electrolytes. Synthetic strategies such as doping, alloying, and fine-tuning surface morphology as well as phase engineering, defect engineering, and strain engineering of TMPs have been discussed. The promising catalyst design considerations by changing surface wettability in creating TMPs and other necessary and sufficient structural prerequisites with upgraded execution for transition metal phosphide nanomaterials (TMPNs) are discussed. This review also provides insight into the electrocatalytic parameters of TMPs derived from Ni, Co, Fe, Mo, and other phosphides by tuning the stoichiometric scale of metal with phosphorous from different sources to realize suitable electrocatalyst systems for water-splitting applications. The element P belongs to the nitrogen group, which holds multielectron orbitals, so P is likely to possess superior chemical properties compared to the N atom. Due to native properties in its electronic structure, P derivatives show promising performances in electrochemical applications. Finally, the challenges and prospects of TMPs in water splitting are methodically illustrated.