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

TiO 2 crystal phase regulates oxide-support interaction strength in CeO 2 /TiO 2 . • Rutile-derived interfaces show stronger Ce-to-Ti charge transfer and higher Ti 3+ fractions. • CeO 2 /TiO 2 -R has lower oxygen-vacancy formation energy and enhanced oxygen activation. • 90% toluene conversion occurs approximately 70 °C lower on CeO 2 /TiO 2 -R than on CeO 2 /TiO 2 -A. Controlling the oxide–oxide interface is crucial for designing efficient oxide catalysts for volatile organic compound (VOC) oxidation, yet how the TiO 2 crystal phase regulates oxide-support interaction remains poorly understood. Here, CeO 2 supported on rutile (R) and anatase (A) TiO 2 was investigated as a model system for toluene oxidation. CeO 2 /TiO 2 -R exhibits markedly higher activity than CeO 2 /TiO 2 -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 CeO 2 /TiO 2 interface exhibits stronger interfacial coupling and more pronounced electron redistribution between CeO 2 and TiO 2 , accompanied by a higher Ti 3+ -related contribution under oxidative conditions. In situ electron paramagnetic resonance measurements, together with density functional theory calculations, reveal enhanced oxygen activation at the CeO 2 /TiO 2 -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 CeO 2 /TiO 2 -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. Download: Download high-res image (496KB) Download: Download full-size image