LAUSR

Understanding and enhancing the activity of heterogeneous single‐atom catalysts (SACs) are indispensable aspects to use them in industrial applications. Among these, low‐temperature CO oxidation is considered as a model reaction for testing a wide‐range of oxidation catalysts, and as an essential process for the exhaust aftertreatment in modern combustion engines. This study demonstrates that the activity of heterogeneous Cu/CeO2−TiO2 SAC catalysts can be fine‐tuned by controlling the Ce/Ti ratio in CeO2−TiO2 supports, with the highest catalytic activity achieved for a Ce/Ti molar ratio of 0.18. Based on DRIFT, EEL, and EPR spectroscopies, together with high‐resolution electron microscopy and H2‐TPR measurements, it is inferred that the optimized Ce/Ti ratio correlates with i) highest dispersion of separate CeO2 particles on TiO2 surface, ii) more facile reduction of Ce4+ to Ce3+, and iii) enhanced formation of −Cu2+−O−Ce4+−⇆−Cu+−□−Ce3+− redox shuttles, which play a dual role for CO adsorption and O2‐activation. These results extend the understanding of heterogeneous metal single‐atom catalysts and constitute a robust approach for the rational control of their catalytic performance in technically relevant applications.