Spatial and electronic structure of the Ni3P surface

To understand the catalytic effect in the Ni-Ni3P for the growth of carbon nanostructures, the structural and electronic properties of Ni3P surface are calculated from first-principles calculations. The calculated surface energies for the (0 0 1)-Ni4P4-terminated surface, the (0 0 1)-Ni8-terminated surface, and the (1 1 0)-Ni8-terminated surface show that the (0 0 1)-Ni4P4-terminated surface is energetically more stable within the allowed range of the chemical potential of P. Through the analysis of the partial density of states of Ni and P atoms in surface and bulk states, respectively, it is further found that due to the bond contractions of the surface layer, the core-level shifts of P atoms in the (0 0 1)-Ni4P4-terminated surface make P atoms in the Ni3P particles act as a catalyst. Finally, the obtained results of the work function show that the (0 0 1)-Ni4P4-terminated surface has the largest work function when compared with the other two studied surfaces.