Highly efficient hydrogen evolution from water electrolysis using nanocrystalline transition metal phosphide catalysts

Nanocrystalline transition metal phosphides (CoP and Ni2P) were successfully synthesized by a simple calcination method by using transition metal hydroxides and NaH2PO2 as raw materials. Their catalytic activities for the hydrogen evolution from water electrolysis were evaluated with silicotungstic acid as an electron-coupled-proton buffer, whereby hydrogen and oxygen could be produced separately. It was found that the CoP sample showed higher catalytic activity (32 mmol min−1 g−1) and good stability (12 h) as compared to the Ni2P sample, and its catalytic activity could rival that of the commercial Pt/C catalyst. The electrochemical results revealed that CoP had high cathodic current and small charge transfer resistance, which further suggested it was indeed an efficient noble metal-free catalyst for hydrogen evolution from water electrolysis.