Abstract:

Density functional theory and periodic slab model were adopted to systemically study NO adsorption, dissociation and N₂ formation on Ir(110) surface. The results show that the most of stable sites are the top sites with the nitrogen bonding to Ir atoms, the shortbridge sites are less stable and the hollow sites are the  least of all. There are two paths for the  dissociation of NO adsorbed on the top sites: One is direct dissociation; and the other  is diffusion from top site to shortbridge site firstly and then dissociation. The results of potential energy surface show that the second path is more favorable than the first one, and is the primary path for NO dissociation. Two N atoms from the dissociated NO form a dishortbridge structure to recombine into N₂.  In addition, the predosed O atom enhances the N atoms combination reaction, which is consistent well with experiment result.

Key words: density functional theory, NO dissociation, N₂ formation, Ir(110) surface, transition state