Vacancy engineering induced reaction kinetics enhancement of cobalt metaphosphate for pH-universal hydrogen evolution

Developing efficient pH-universal hydrogen evolution reaction (HER) catalysts is critical in the field of water electrolysis, however, which is severely hampered by the sluggish kinetics in alkaline media. Herein, a ruthenium (Ru) incorporation induced vacancy engineering strategy is firstly proposed to precisely construct oxygen vacancy (V_O)-riched cobalt-ruthenium metaphosphate (CRPO) for high-efficiency pH-universal HER. The V_O modifies the electronic structure, improves the superficial hydrophilic and gas spillover capacity, it also reduces the coordination number of Ru atoms and regulates the coordination environment. Theoretical calculations indicate that Ru tends to adsorb H₂O and H*, whereas V_O tends to adsorb OH⁻, which greatly promotes the H₂O adsorption and the dissociation of HO–H bond. Ultimately, CRPO-2 exhibits remarkable HER performance, the mass activity is about 18.34, 21.73, and 38.07 times higher than that of Pt/C in acidic, neutral, and alkaline media, respectively, at the same time maintain excellent stability. Our findings may pave a new avenue for the rational design of electrocatalysts toward pH-universal water electrolysis.