CO oxidation on ${\mathrm{P}\mathrm{t}\mathrm{O}}_2(110)$ has been studied using density functional theory calculations. Four possible reaction mechanisms were investigated and the most feasible one is the following: (i) the O at the bridge site of ${\mathrm{P}\mathrm{t}\mathrm{O}}_2(110)$ reacts with CO on the coordinatively unsaturated site (CUS) with a negligible barrier; (ii) ${\mathrm{O}}_2$ adsorbs on the bridge site and then interacts with CO on the CUS to form an OO-CO complex; (iii) the bond of O-OCO breaks to produce ${\mathrm{C}\mathrm{O}}_2$ with a small barrier (0.01 eV). The CO oxidation mechanisms on metals and metal oxides are rationalized by a simple model: The O-surface bonding determines the reactivity on surfaces; it also determines whether the atomic or molecular mechanism is preferred. The reactivity on metal oxides is further found to be related to the 3rd ionization energy of the metal atom.

• Received 19 April 2004

DOI:https://doi.org/10.1103/PhysRevLett.93.106104