Figure 4.
a) Total and partial electronic density of states (TDOS and PDOS) calculated for Ni3N1− x. The Fermi level is set at 0 eV. The inset shows the atomic structure model of Ni3N1− x. b) Partial charge density distribution of Ni3N1− x. c) Adsorption energies of H2O molecules on the surfaces of Ni3N and Ni3N1− x. The inset is a side‐view schematic model showing the Ni3N1− x structure with a H2O molecule adsorbed on its surface. d) The calculated free‐energy diagram of HER at the equilibrium potential for Ni3N, Ni3N1− x, and Pt reference. H* denotes that intermediate adsorbed hydrogen.