Mechanistic insights into hydrogen evolution reaction on Ni2B(001) facet using first-principle calculations

In this paper, first-principle calculations based on density functional theory (DFT) were used to investigate the performance and mechanism of the hydrogen evolution reaction (HER) on the typical active (001) facet of the novel electrocatalyst Ni2B. There were two types of atomic distribution on the Ni2B (001) surface, namely the B-rich surface and the Ni-rich surface. The investigation of the reaction mechanism revealed that the Volmer-Heyrovsky mechanism was easier to be realized on this Ni2B (001) facet, and the Heyrovsky reaction was the reaction rate-determining step. The Gibbs free energy(ΔGH) on the B-rich surface was - 0.02 eV, which was closer to 0 eV than that on the Ni-rich surface of Ni2B (001). The HER reactivity on the Ni-rich surface was increased by Cr-doping (ΔGH = - 0.01 eV), which indicated that the introduction of other transition metal atoms might effectively increase the HER electrocatalysis activity of Ni2B (001) surface. This work paves a new avenue for exploring efficient and durable non-precious metal electrocatalysts for HER in acidic medium.