Fig. 5

Electronic structure of Mo₂N and P–Mo₂N. DFT calculation: a model of bare Mo₂N (112) facet; b model of P doped Mo₂N (112) surface, one N atom was replaced by one P atom; the blue, cyan, and pink spheres are Mo, N, and P atoms, respectively. The dotted gray box in a or b is the framework of the model. c Free energy diagrams for hydrogen adsorption at different sits (Mo, N, and P) on the (112) surface of bare Mo₂N and P doped Mo₂N; computational densities of states (DOS) of (d) N-p orbital in bare Mo₂N (112) surface, P-p orbital in P doped Mo₂N (112) surface and e Mo-d orbital in bare and doped Mo₂N (112) surface. f Ultraviolet-photoelectron spectra of Mo₂N and P doped Mo₂N samples. For the sample of P doped Mo₂N, a tail can be found as depicted by the blue arrow