Catalytic oxidation of CO on Ir(100)

Density functional theory (DFT) calculations are performed to investigate the CO oxidation on Ir(100) surface at different CO coverages, 0.125, 0.25, and 0.5 monolayers (ML). The reaction pathway and transition state (TS) are determined using constrained minimization and nudged elastic band (NEB) methods. We found that the CO molecule is significantly more mobile toward O atoms, which causes a weakening of the O-metal bond. The increase of CO coverage leads to a decrease in the activation energy of the reaction and an increase of O(a)-CO distance where O coverage is kept at 0.25 ML. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim