DFT insights into hydrogen activation on the doping Ni2P surfaces under the hydrodesulfurization condition

Hydrogen activation on the different Ni2P surfaces were explored under the traditional hydrodesulfurization conditions using density function theory (DFT) calculations. Firstly, the H2 dissociative adsorption phase diagrams were calculated and compared on the Ni(I)- and Ni(II)-exposed surfaces. The H2 dissociative adsorption on the Ni(I)-exposed surface had high activity below 4 H2 coverage, and the H2 dissociative adsorption on the Ni(II)-exposed surface was preferable below 2 H2 coverage. By contrast, the Ni(I)-exposed surface exhibited higher H2 activation activity than that on the Ni(II)-exposed surface. Moreover, the dissociative H atoms on Ni(II)-exposed surface would lead the rearrangement of surface Ni atoms to form the quasi tetrahedral coordination structure, which was similar to that of Ni(I)-exposed surface. Secondly, the surface phase diagrams were discussed on the different transition metals (Cr, Fe, Co, Cu or Mo) doping Ni(I)-exposed surfaces. The results revealed that H2 activation ability followed the order: Fe > Co > Mo > Cr > Ni > Cu. Furthermore, the difference charge densities and bader charge analysis were calculated to provide the additional information for understanding the phenomenon clearly, and the results indicated that the difficulty sequence of charge transfer between transition metals atom and H atoms was completely consistent with the above research.