Spatially Resolved Geometric and Electronic Structure at Ru‐TiO ₂ Interface by EELS at Very High Energy Losses

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The interfacial structure between metal nanoparticles and oxide supports critically influences catalytic performance, yet resolving their local geometric and electronic features at the atomic scale remains challenging. In this study, aberration‐corrected scanning transmission electron microscopy (STEM) combined with monochromated electron energy loss spectroscopy (EELS) is employed at very high energy losses (>2000 eV) to investigate Ru–TiO 2 interfaces in catalysts with distinct TiO 2 crystalline phases. High‐resolution STEM and EELS mapping reveal phase‐dependent TiO x overlayer structures: atomically thin in Ru/P25‐TiO 2 , and thicker amorphous or island‐like in rutile‐ and anatase‐supported counterparts. Fine‐structure analysis of Ti‐L 2 , 3 and O‐K edges shows that Ru/P25‐TiO 2 exhibits a lower Ti 3 ⁺ fraction (30.2%) and reduced Ru‐to‐TiO 2 charge transfer, which enhances CO adsorption and promotes its hydrogenation to CH 4 . Extended energy‐loss fine structure (EXELFS) analysis of Ti‐K spectra further discloses elongated Ti─O bonds (1.86 vs bulk 1.83 Å), indicating the formation of Ti 3+ ‐O V ‐Ru δ+ interfacial sites. These interfacial characteristics correlate with superior CO 2 hydrogenation performance, achieving >99% CO 2 conversion and >96% CH 4 selectivity. This work highlights the power of high‐resolution EELS and EXELFS in unveiling sub‐nanometer interfacial structures and offers a new strategy for rational catalyst design through control of metal–support interactions.