TiO2-facet-dependent reconstruction of Pt nanoparticles during CO oxidation.

Facet engineering of reducible oxide supports is a powerful strategy for tuning metal-support interactions. We show that this facet dependence extends beyond intrinsic support properties to govern the initial morphology and reaction-induced restructuring behaviour of supported Pt nanoparticles during CO oxidation. For ~1.8 nm Pt nanoparticles on anatase TiO2, microscopy and spectroscopy show that the (001) facet stabilises a wetted Pt structure with expanded interfacial contact, whereas the (101) facet favours compact cuboctahedral nanoparticles with limited interface. Genetic algorithm and graph neural network-based simulations reproduce these facet-dependent structures and support distinct restructuring under CO oxidation. DFT calculations support facile oxygen activation on the (001) facet throughout the MvK pathway, while reaction-order analysis and catalytic cycle tests indicate that the reaction-evolved Pt-TiO2(001) interface synergistically couples with oxygen vacancies to enable efficient oxygen replenishment, further lowering the activation barrier by ~25% after the initial run. This work identifies support facets as regulators of dynamic metal-support interfaces governing catalytic performance.