Sulfur doping enhanced desorption of intermediates on NiCoP for efficient alkaline hydrogen evolution.

ABSTRACT

Electrocatalysts with high catalytic activity, high stability and low cost are critical to the hydrogen evolution reaction (HER). In this paper, sulfur(S)-doped NiCoP nanowire arrays on a carbon fiber paper skeleton (S-NiCoP NW/CFP) are prepared, and it is demonstrated that the electrocatalytic properties of NiCoP in alkaline solution could be well improved by sulfur doping. In 1.0 M KOH, only an overpotential of 172 mV (vs. RHE) at 100 mA cm-2 is required for S doped NiCoP nanowires on CFP, and the turnover frequency (TOF) is 1.71 times that of NiCoP at an overpotential of 100 mV, indicating its superior intrinsic activity. Density functional theory (DFT) calculations show that S doping could lower the center of the d-band, and thus weaken the interaction between NiCoP and the intermediates. This leads to an optimized hydrogen adsorption Gibbs free energy (ΔGH*) and faster desorption of OH*. This study offers a promising way to design and optimize electrocatalysts for the HER in alkaline solution.