| AVS 55th International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS-TuP |
| Session: | Surface Science Poster Session |
| Presenter: | M.C.S. Escano, Osaka University, Japan |
| Authors: | M.C.S. Escano, Osaka University, Japan H. Kasai, Osaka University, Japan |
| Correspondent: | Click to Email |
Bimetallic surfaces have been receiving increasing catalytic interest. Aside from using strain to tune reactivity, to a large extent, metal overlayers exhibit modified surface electronic structure due to interfacial interactions.1,2 While dissociative adsorption of small molecules on metal surfaces has been studied extensively, theoretical studies on gas-bimetallic surface interaction have been sparse. Previous ab-initio calculations on atomic and electronic structure of Pt/Fe(001) show small lattice mismatch and a charge transfer from Pt and Fe atom sites towards Pt-Fe interface.3 Layer by layer density of states curves against Pt(001) and Fe(001) show increase of d states at the Fermi level and a spin polarization of Pt dzz states. Such changes with respect to the pure components call for investigation on O2 surface reactivity. Spin-polarized density functional theory calculations were performed to investigate adsorption and O2 dissociation on Pt/Fe(001). The adsorption characteristics of atomic and molecular oxygen are compared with clean Pt(001). The energetics of O2 adsorption and dissociation are discussed in terms of two-dimensional cuts of the six-dimensional potential-energy surface. Results show "no barrier" O2 molecule preferential adsorption on bridge with O-O axis directed towards top sites (t-b-t). A barrierless dissociation over one trajectory, O-O axis parallel and spanning over bridge-hollow-bridge (b-h-b) site, is also predicted. The potential energy decreases monotonically along this lowest energy reaction path indicative of strong O2 interaction with the surface. A proposed pathway for dissociation may take molecular adsorption along t-b-t and a translation and dissociation towards b-h-b. Detailed analysis of the transition state reveals ease of translation towards the b-h-b. Local density of states (LDOS) of O2 arriving over bridge for the molecular state and at the transition state support strong hybridization between O2 px-states and Pt dzz states. In the meeting, we will detail the mechanism of O2 reactivity based on charge redistribution, total charge flow integrals and partial charge density plots.
1 M. Mavrikakis, B. Hammer and J.K. Nørskov, Phys. Rev. Lett. 81, 2819 (1998).
2 J.A. Rodriguez, Surf. Sci. Rep. 24, 223 (1996)
3 MC Escaño, H. Nakanishi and H.Kasai, J. Phys.: Cond. Matt. 19, 482002 (2007).