Boosting Oxygen Activation via Defect Engineering to Regulate CO Oxidation Pathway over Pt/TiO₂ Catalysts

Defect engineering has attracted great attention due to its important role in promoting metal dispersion and regulating catalytic performance. In this study, a gentle method for stabilizing metal single atoms and adjusting the metal coordination environment was proposed, wherein the chemical etching of a Ti–Si oxide composite by NaOH was employed to construct a defect structure. As a conceptual proof, a defective catalyst loaded with 0.1 wt % Pt was synthesized, which exhibited a complete CO oxidation temperature of 200 °C, a significant 70 °C decrease compared to the conventional catalyst. Characterization and theoretical calculations confirmed that Pt existed as single atoms on the defective catalyst, and O2 was adsorbed and activated at Ti3+ defect sites. Notably, the CO oxidation followed the Mars-van Krevelen (MvK) mechanism, resulting in a remarkably low oxygen activation energy barrier of 0.38 eV on the defective catalyst, significantly lower than that on the conventional catalyst (2.48 eV), consistent with its enhanced low-temperature activity. This work provides a promising strategy for the design of efficient and stable low-load noble metal catalysts on oxide-based supports.