Crystal phase-regulated strong oxide-support interactions in CeO₂/TiO₂ catalysts for toluene oxidation

Controlling the oxide-oxide interface is crucial for designing efficient oxide catalysts for volatile organic compound (VOC) oxidation, yet how the TiO₂ crystal phase regulates oxide-support interaction remains poorly understood. Here, CeO₂ supported on rutile (R) and anatase (A) TiO₂ was investigated as a model system for toluene oxidation. CeO₂/TiO₂-R exhibits markedly higher activity than CeO₂/TiO₂-A, with the temperature required for 90% toluene conversion lowered by approximately 70 °C. High-resolution transmission electron microscopy and quasi-in situ X-ray photoelectron spectroscopy show that the rutile-derived CeO₂/TiO₂ interface exhibits stronger interfacial coupling and more pronounced electron redistribution between CeO₂ and TiO₂, accompanied by a higher Ti³⁺-related contribution under oxidative conditions. In situ electron paramagnetic resonance measurements, together with density functional theory calculations, reveal enhanced oxygen activation at the CeO₂/TiO₂-R interface, associated with a lower interfacial oxygen-vacancy formation energy and promoted lattice‑oxygen activation as well as reactive oxygen species generation. Temperature-programmed infrared spectroscopy further shows faster turnover of toluene-derived oxygenated intermediates on CeO₂/TiO₂-R, with benzyl alcohol, benzaldehyde, and benzoate species identified along the reaction pathway, supporting an enhanced Mars-van Krevelen oxidation pathway enabled by enhanced oxygen activation. This work highlights crystal-phase engineering of oxide supports as an effective strategy to regulate oxide-oxide interfacial redox chemistry and improve VOC oxidation performance.