Enhancing Molecular Oxygen Activation for Light Alkane Oxidation on Stabilized Ru/CeO ₂ /TiO ₂ Nanoisland Catalysts via Ru 4d−O 2p−Ce 4f Orbital Coupling Engineering

The limitations of single-atom catalysts in structural stability and molecular oxygen activation impeded their efficiency for low-temperature catalytic oxidation of light alkanes. Herein, we report a strategy mediated by high-energy Ce 4f orbitals for stabilizing single-atom Ru sites on Ru/CeO 2 /TiO 2 nanoisland catalysts via engineered Ru 4d−O 2p−Ce 4f orbital coupling, which effectively suppresses atomic aggregation and significantly enhances O 2 activation. Combined experimental and theoretical calculations demonstrate that the orbital structure facilitates interfacial electron transfer from CeO 2 toward Ru sites, significantly promoting O 2 activation into a superoxide radical (O 2 · − ) for oxidation efficiency of light alkanes. The Ru/CeO 2 /TiO 2 catalyst achieves T 50 and T 90 ( T 50 and T 90 represent the temperatures at which the propane conversion reaches 50% and 90%, respectively) of 178 and 224 °C for propane oxidation, which are 89 and 108 °C lower than those of Ru/CeO 2 -TiO 2 (267 and 332 °C), respectively. Mechanistic investigations reveal that propane catalytic oxidation over Ru/CeO 2 /TiO 2 predominantly via the Langmuir−Hinshelwood pathway, with Ru 4d−O 2p−Ce 4f orbital coupling markedly accelerating the cleavage of the C═O bond in the acetone intermediate (rate-determining step). Moreover, this low-temperature activity enhancement could extend similarly to the catalytic oxidation of methane and ethane. This work provides a rationally catalyst construction-designed strategy to enhance O 2 activation and efficient catalytic oxidation of refractory light alkanes.