Theoretical and Experimental Investigations on Single-Atom Catalysis: Ir1/FeOx for CO Oxidation

Through periodic density functional theory (DFT) calculations we have investigated the catalytic mechanism of CO oxidation on an Ir-1/FeOx single-atom catalyst (SAC). The rate-determining step in the catalytic cycle of CO oxidation is shown to be the formation of the second CO2 between the adsorbed CO on the surface of Ir-1/FeOx and the dissociated O atom from gas phase. Comparing with Pt-1/FeOx catalyst, the reaction activation barrier for CO oxidation is higher by 0.62 eV and the adsorption energy for CO molecule is larger by 0.69 eV on Ir-1/FeOx. These results reveal that Ir-1/FeOx catalyst has a lower activity for CO oxidation than Pt-1/FeOx, which is consistent with our experimental results. The results can help to understand the fundamental mechanism of monodispersed surface atoms and to design highly active single-atom catalysts.