2D NiP/N-doped graphene heterostructure as a Novel electrocatalyst for hydrogen evolution reaction: A computational study.

The main prerequisite for designing electrocatalysts with favorable performance is to examine the links between electronic structural features and catalytic activity. In this work, NiP as a model electrocatalyst and one of the most potent catalysts for hydrogen evolution reaction (HER) was utilized to develop various NiP and carbon-based (graphene and N-doped graphene) heterostructures. The characteristics of such structures (NiP, graphene, N-doped graphene, NiP/graphene, and NiP/N-doped graphene), including binding energies, the projected density of states (PDOS), band structure, charge density difference, charge transfer, Hirshfeld charge analysis, and minimum-energy path (MEP) towards HER were calculated and analyzed by density functional theory (DFT) approach. The coupling energy values of hybrid systems were correlated with the magnitude of charge transfer. The main factors driving a promising water-splitting reaction were explained by the data of PDOS, band structures, and charge analysis, including the inherent electronegativity of the N species alongside shifting the Fermi level toward the conductive band. It was also shown that a significant drop occurs in the HER energy barrier on NiP/graphene compared to the pristine NiP due to N doping on the graphene layer in the NiP/N-doped graphene heterostructure.