First principle study on alkali metals promotion of CO oxidation over Ir(100)

The effects of adsorption of lithium and potassium atoms on CO oxidation at Ir(100) surface are investigated by using density functional theory (DFT) within generalized gradient approximation (GGA). The reaction path, transition state, and energy barrier are obtained by using climbing image nudged elastic band method (CI-NEB). The results of CO oxidation on Ir(100)-(3 x 2) clean surface indicate that the energy barrier is related to the changes of energy that caused by the movements of the reactant from the initial state to the transition state. The coadsorption of A (A for alkali, A = Li or K) atoms on Ir(100)-(3 x 2)-(CO-O) system promote the CO oxidation. In particular, the alkali atom induces changes in the reaction path and energy barrier. Potassium atom induces a large reduction in the reaction barrier more than Li atom. K atom interacts directly with the reactant, which stabilizes the reactant and increases the reactivity of the catalyst. The bent CO2 appears at the transition state for CO oxidation reaction on both alkali-precovered Ir(100) surface (A = K or Li). (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim