Density Function Theoretical Investigation on the Ni3PP Structure and the Hydrogen Adsorption Property of the Ni2P(0001) Surface

Hiroko Ariga, Mayumi Kawashima, Satoru Takakusagi, Kiyotaka Asakura
2013 Chemistry Letters  
Electronic and structural properties of phosphorus terminated structure of Ni 2 P(0001) surface(Ni 3 PP) are investigated by density functional theoretical (DFT) calculation. Phosphorus adsorption largely stabilizes the Ni 2 P(0001) surface by creating Ni-P bonds on the Ni trimer. Atomic hydrogen can adsorb on the topmost P site but its adsorption energy is much lower than its adsorption energy on the Ni trimer site of Ni 3 P 2 surface. Our results suggest that the Ni trimer is the key factor
more » ... r high catalytic activity. Nickel phosphide (Ni 2 P) shows a high catalytic activity for the hydrodesulfurization[1] and other hydrotreatment catalyses towards hydrodenitrogenation and hydrodeoxidation and so on. [2] The key issue to understand the hydrogenation reactions is interaction between hydrogen with Ni 2 P surface in an atomic level. The bulk structure of Ni 2 P is composed of two different layers with different composition, Ni 3 P 2 and Ni 3 P 1 , aligning alternately along the [0001] direction as shown in Figure 1(a) . Rodriguez et al. showed that Ni 3 P 2 surface was more stable surface than Ni 3 P 1 surface and they discussed the hydrogen adsorption properties on the Ni 3 P 2 surface.[3] However, scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) studies on the Ni 2 P(0001) have revealed that the Ni 2 P(0001) surface is mainly (about 80 %) covered with phosphorus on the Ni three fold site of Ni 3 P 2 surface after 953 K annealing under UHV conditions with minor amount of uncovered Ni 3 P 2 surface. [4] [5] [6] This new phosphorus covered surface is called as Ni 3 PP surface. Similar phosphorus terminated surface was reported on the reconstructed (10-10) surface by STM observation [7] . The phosphorus termination of the surfaces were supported by
doi:10.1246/cl.130710 fatcat:vszsfzllo5fzzbk5jqch3lhlpm