Functional Cooperation between Pt Single Atoms and Nanoparticles on TiO 2 for Photocatalytic Dehydrogenation and C–C Coupling

Abstract Dehydrogenative coupling reactions that activate inert C–H bonds for C–C bond formation remain challenging because of unfavorable thermodynamics and kinetics without external oxidants. We report a hybrid photocatalytic system consisting of mixed Pt species on TiO2 (Ptmix/TiO2) combined with the hydrogen atom transfer reagent 2,2,2-trichloroethanol (TCE) for the dehydrogenative coupling of toluene. The system delivers 11% toluene conversion with 94% selectivity to bibenzyl and stoichiometric H2 evolution. Mechanistic studies show that Pt single atoms (Pt1) act as hole acceptors, while Pt nanoparticles (Pt NPs) act as electron acceptors, which further enhances charge separation. Holes localized on Pt1 oxidize TCE to generate chlorine radicals that mediate benzylic C–H abstraction, and electrons accumulated on Pt NPs drive proton reduction to H2. This work highlights the synergy between a semiconductor photocatalyst and a HAT (hydrogen atom transfer) mediator and the complementary roles of distinct Pt configurations, offering a guiding principle for designing efficient photocatalytic systems for organic synthesis.