Reactants have a lower energy barrier for catalytic oxidation or may create reaction-promoting free radicals on the surface of SACs, which is beyond the reach of conventional catalysts. In the study of catalytic oxidation of CO, single-atom Pt exhibited high selectivity for O2 and weak bonding for CO, which facilitated the reaction between O2 and CO molecules. Therefore, SACs with high activity and high adsorption selectivity are the targets of our study.