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

Facet engineering of metal-support interactions is a powerful approach for optimising catalytic activity. We investigated how exposed (001) and (101) facets of anatase TiO ₂ influence the structure and reactivity of ~1.8 nm Pt nanoparticles (NPs) during CO oxidation. The (001) facet stabilises the undercoordinated Pt clusters with expanded interfacial contact, whereas the (101) facet favours well-coordinated cuboctahedral NPs with confined interfaces. Correlative microscopy and spectroscopic analyses confirmed that the observed reconstructions were driven by both facet-dependent surface properties and CO-induced effects. Structural differences were captured using density functional theory (DFT) and graph-neural-network-based molecular dynamics simulations. DFT calculations revealed exergonic lattice oxygen activation on the (001) facets via the Mars-van-Krevelen mechanism, compared to a 1.75 eV thermodynamic barrier on (101), in agreement with the experimentally observed lower activation energy (55 vs. 112 kJ mol ^–1 ). Our findings underscore the critical role of support facet engineering in controlling the NP structure and catalytic performance.