Site-Selective Loading of Single-Atom Pt on TiO₂ for Photocatalytic Oxidation and Reductive Hydrodefluorination

Separating the redox sites of photocatalysts is one of most promising strategies to promote an efficient photoinduced charge transfer of semiconductor photocatalysis. Herein, we present a site-selective loading of single-atom Pt (Pt1) on facet-engineered TiO2 to achieve decomposition of recalcitrant halogenated water pollutants, including perfluorooctanoic acid (PFOA). Positively charged Pt1 are atomically dispersed catalytic sites that are selectively loaded onto the reductive sites of tailored TiO2 to attract the photoinduced electrons efficiently. This enhances the number of holes, and consequently hydroxyl radicals, remaining on the sites of facet-engineered TiO2, confirmed by the enhancement of degradation of sulfamethoxazole and 2,4-dichlorophenoxyacetic acid. While Pt nanoparticle cocatalysts consume photoinduced electrons for the reduction of oxygen molecules, site-specifically loaded Pt1 produce surface hydrogen atoms and enhance hydrogen spillover onto the TiO2 surface, to achieve efficient hydrodefluorination of PFOA via the cleavage of the C–F bond with the Ti–H bond. The site-selective loading of Pt1 on facet-engineered TiO2 serves as a versatile platform that harnesses both reductive and oxidative degradation of emerging aqueous pollutants.