Doping and strain effect on hydrogen evolution reaction catalysts of NiP2

Hydrogen production through electrolyzing water can transfer the energy from solar energy, wind energy and other sustainable energy to hydrogen, a clean energy carrier with high energy density. The NiP2 has attracted much attention as a cheap electrocatalyst with high catalytic performance for hydrogen evolution reaction (HER). In this paper, the adsorption energy, Gibbs free energy and exchange current densities at different sites on NiP2 (100) surface are calculated. On this basis, the effect of strain and doping on the HER catalytic performance of NiP2 are studied. By calculation, we find that when H is adsorbed on the top site of P atom on NiP2 (100) surface, the exchange current density is the closest to the top of volcanic curve, so the top site of P atom on NiP2 (100) surface is the catalytic active site. The effect of doping and strain on the catalytic performance of NiP2 are analyzed. 1) According to the range of strain produced by the common experimental technology, the effects of 1% and 3% tensile and compressive strain are calculated. It is found that 1% compressive strain can improve the catalytic performance of NiP2, while when 3% compressive strain or a 1% or 3% tensile strain is applied, the catalytic performance of NiP2 is not enhanced. 2) The effects of doping transition metal elements (Co, Fe, Mn, Mo, Cu, W, Cr) and non-metallic elements (N, C, S) on the catalytic performance of NiP2 are calculated. It is found that doping non-metallic element S can significantly improve the HER catalytic performance of the top site of P atom, while the doping of transition metal elements Mn, Mo, W, Co, Cr, Fe, Cu and non-metallic elements N, C have no effect on this site. The doping of transition metal element (catalytic activity: Mn > Mo > W > Co > Cr > Fe > Ni) Mn can make the catalytic performance of inactive site improved to that of the active site, thus indirectly improving the catalytic performance of NiP2. Our work reveals the micro mechanism of the effect of doping and strain on the performance of HER electrocatalyst, which provides a new perspective for designing the high performance HER electrocatalyst.

Automated summary

This study reveals that doping non-metallic element sulfur can significantly improve the HER catalytic performance of the top site of P atom on NiP2, while the doping of transition metal elements and non-metallic elements have no effect on this site. Doping transition metal element manganese can improve the catalytic performance of inactive site to that of the active site, indirectly enhancing the overall performance of NiP2 as a HER electrocatalyst.