A review of typical transition metal phosphides electrocatalysts for hydrogen evolution reaction

Hydrogen energy is a clean, carbon-free and potential future energy source. Hydrogen generation by electrochemical water splitting becomes a promising approach, which is highly dependent on the electroactivity of hydrogen evolution reaction (HER) electrocatalysts. The transition metal phosphides (TMPs) become promising electrocatalysts due to low overpotential, good electrochemical stability and high electrocatalytic activity. This review mainly summarizes HER mechanisms, preparation methods, electrocatalytic assessment and microstructure regulation of TMPs. The electrochemical properties of five typical TMPs (NixPy, CoxPy, MoxPy, WxPy and FexPy) under different phosphating degrees are intensively compared. Since the electrocatalytic performance of current TMPs is insufficient for industrial applications, new design and preparation methods for nanostructure-controlled TMPs electrocatalysts are proposed. In particular, the development of element-doped, self-supporting nanomaterials is the future development direction of TMPs electrocatalysts that can be applied in the whole pH range.