Partial PdAu nanoparticle embedding into TiO₂ support accentuates catalytic contributions from the Au/TiO₂ interface

Despite the broad catalytic relevance of metal-support interfaces, controlling their chemical nature, the interfacial contact perimeter (exposed to reactants), and consequently, their contributions to overall catalytic reactivity, remains challenging, as the nanoparticle and support characteristics are interdependent when catalysts are prepared by impregnation. Here, we decoupled both characteristics by using a raspberry-colloid-templating strategy that yields partially embedded PdAu nanoparticles within well-defined SiO₂ or TiO₂ supports, thereby increasing the metal-support interfacial contact compared to nonembedded catalysts that we prepared by attaching the same nanoparticles onto support surfaces. Between nonembedded PdAu/SiO₂ and PdAu/TiO₂, we identified a support effect resulting in a 1.4-fold higher activity of PdAu/TiO₂ than PdAu/SiO₂ for benzaldehyde hydrogenation. Notably, partial nanoparticle embedding in the TiO₂ raspberry-colloid-templated support increased the metal-support interfacial perimeter and consequently, the number of Au/TiO₂ interfacial sites by 5.4-fold, which further enhanced the activity of PdAu/TiO₂ by an additional 4.1-fold. Theoretical calculations and in situ surface-sensitive desorption analyses reveal facile benzaldehyde binding at the Au/TiO₂ interface and at Pd ensembles on the nanoparticle surface, explaining the connection between the number of Au/TiO₂ interfacial sites (via the metal-support interfacial perimeter) and catalytic activity. Our results demonstrate partial nanoparticle embedding as a synthetic strategy to produce thermocatalytically stable catalysts and increase the number of catalytically active Au/TiO₂ interfacial sites to augment catalytic contributions arising from metal-support interfaces.