Theoretical expectation and experimental investigation on the feasibility of N-doped Ni2P as highly active hydrogen evolution catalyst

Abstract

In this paper, N-doped Ni2P (N-Ni2P) as a catalyst for hydrogen evolution was proposed. Firstly, the feasibility of N atom doping was calculated by density functional theory (DFT). Ni top site, Ni bridge site, Ni hollow site and P top site were calculated for Ni2P (001) and N-Ni2P (001). The results confirm that N atom doping can make the Gibbs free energy (ΔGH∗) closer to thermal neutrality (ΔGH∗ = 0) and move the d-band center away from Fermi level. Besides, charge density difference pattern and bader charge indicate N atom doping regulate the charge structure of the catalyst surface. Based on the guidance of DFT calculation results, Ni2P and N-Ni2P catalysts were also experimentally synthesized. It is revealed that the N-Ni2P can achieve cathodic current densities of 10 mA cm−2 and 100 mA cm−2 at overpotentials of 110 mV and 302 mV in 1.0 M KOH and 82 mV and 235 mV in 0.5 M H2SO4, respectively. This work shows that it is feasible to increase HER performance by modifying Ni2P catalyst with N doping.