No abstract

In order to understand relation between surface structure and catalytic activity, we studied the Ni2P (1010) surface using scanning tunneling microscopy (STM). Atomic scale STM images of c(2×4) structure and (1×1) structure were obtained after annealing the sample at 653 K (denoted as surface structure I). The area of c (2×4) structure was decreased by the NO exposure at 573 K. A c(2×4) structure together with c(2×2) structure was obtained after the repeated sputtering-annealing treatments and reactions, which was called as surface structure II. Contrary to the surface structure I, this surface didnʼt change its structure by the NO exposure at 573 K. Since the (1×1) structure on the surface structure I had exposed Nit (tetrahedral Ni) and Nisp (square pyramid Ni) pairs, NO might be activated and destroy the c(2×4)structure, while c(2×2) structure on the surface structure II had no exposed Nit and Nisp pair so that surface structure II was less reactive. The removal of the surface P atoms is important for the activation of the Ni2P surface.