Synergistic Pd Single Atoms, Clusters, and Oxygen Vacancies on TiO₂ for Photocatalytic Hydrogen Evolution Coupled...

Developing efficient photocatalysts for synchronously producing H₂ and high value-added chemicals holds great promise to enhance solar energy conversion. Herein, a facile strategy of simultaneously engineering Pd cocatalyst and oxygen vacancies (V_O s) on TiO₂ to promote H₂ production coupled with selective oxidation of benzylamine is demonstrated. The optimized Pd_SA+C /TiO₂ -V_O photocatalyst containing Pd single atoms (SAs), clusters (C), and V_O s exhibits much superior performance to those of TiO₂ -V_O and Pd_SA /TiO₂ -V_O counterparts. The production rates of H₂ and N-benzylidenebenzylamine over Pd_SA+C /TiO₂ -V_O are 52.7 and 1.5 times those over TiO₂ -V_O , respectively. Both experimental and theoretical studies have elucidated the synergistic effect of Pd SAs, clusters, and V_O s on TiO₂ in boosting the photocatalytic reaction. The presence of Pd SAs facilitates the generation and stabilization of abundant V_O s by the formation of PdOTi³⁺ atomic interface, while Pd clusters promote the photogenerated charge separation and afford the optimum active sites for H₂ evolution. Surface V_O s of TiO₂ guarantee the efficient adsorption and dissociation/activation of reactant molecules. This study reveals the effect of active-site engineering on the photocatalysis and is expected to shed substantial light on future structure design and modulation of semiconductor photocatalysts.