CO oxidation on Pt(111) is studied with ab initio density functional theory. The low energy pathway and transition state for the reaction are identified. The key event is the breaking of an O-metal bond prior to the formation of a chemisorbed ${\mathrm{CO}}_2$ molecule. The pathway can be rationalized in terms of competition of the O and C atoms for bonding with the underlying surface, and the predominant energetic barrier is the strength of the O-metal bond.

• Received 11 December 1997

DOI:https://doi.org/10.1103/PhysRevLett.80.3650