| AVS 59th Annual International Symposium and Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS-WeM |
| Session: | Chemisorption on Metallic Surfaces |
| Presenter: | Z. Liang, University of Illinois at Chicago |
| Authors: | Z. Liang, University of Illinois at Chicago H. Kim, RIKEN, Japan Y. Kim, RIKEN, Japan M. Trenary, University of Illinois at Chicago |
| Correspondent: | Click to Email |
The interaction of NH3 with chemisorbed molecular O2 on a Pt(111) surface has been studied at the single-molecule level with low temperature scanning tunneling microscopy. Chemisorbed O2 molecules are found to form an ordered network at high coverages for adsorption temperatures below 50 K. Sites unoccupied by O2 molecules on Pt(111) appear as holes in the network. Various hole-hole distances among nearest neighbors are observed reflecting variations in the arrangement of O2 molecules. A hole-hole distance of 0.74 nm is found to be predominant on the surface and is assigned to be the most favorable one as it maintains the 3-fold symmetry of underlying platinum lattice. Ammonia molecules are observed to adsorb in the holes within the ordered network of O2 molecules, which is also the a-top site with respect to the Pt(111) substrate. Further annealing of the ammonia-oxygen overlayer to 400 K results in the formation of a mixed p(2×2) overlayer of N, O and NH. This work provides new insights into the ammonia oxydehydrogenation reaction on platinum surface, which is an important catalytic reaction in the industrial production of nitric acid.