Construction of NiCo2S4−xPx nanowire arrays for efficient hydrogen evolution reactions in both acidic and alkaline media

Abstract

It is significant to develop low-cost and highly efficient electrocatalysts for the hydrogen evolution reaction (HER) via electrochemical water splitting. Herein, we constructed P-doped NiCo₂S₄ nanowire arrays on carbon fiber paper (NiCo₂S_4−xP_x/CFP) as a HER electrocatalyst in both acidic and alkaline media. Benefitting from P doping into NiCo₂S₄, the as-prepared NiCo₂S_4−xP_x/CFP exhibits low HER overpotentials of 80 and 132 mV in acidic and alkaline media at a cathodic current density of 10 mA cm⁻², respectively, which are far superior to counterparts of NiCo₂S₄ nanowire arrays on the carbon fiber paper (NiCo₂S₄/CFP). Meanwhile, the NiCo₂S_4−xP_x/CFP presents excellent HER stability of 20 hours in acidic and alkaline media. From the results of density functional theory calculations, P doping can not only optimize the hydrogen adsorption energetics on each kind of atomic site of catalysts, but also strengthen the H₂O molecule binding ability on the catalyst surface for the alkaline HER and favor kinetics of hydrogen adsorption and H₂ formation on the catalyst surface for the acidic HER, eventually improving overall HER performances. The investigation of the HER mechanism modulated by P doping in our work offers novel inspiration to develop highly efficient ternary metal sulfides for the HER.