Synergistic Pd Single Atoms, Clusters, and Oxygen Vacancies on TiO2 for Photocatalytic Hydrogen Evolution Coupled with Selective Organic Oxidation

Developing efficient photocatalysts for synchronously producing H-2 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 H-2 production coupled with selective oxidation of benzylamine is demonstrated. The optimized PdSA+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 H-2 and N-benzylidenebenzylamine over PdSA+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 H-2 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.

Automated summary

This study demonstrates the synergistic effect of Pd SAs, clusters, and V(O)s on TiO2 in boosting photocatalytic reactions, leading to improved activity in hydrogen production and selective oxidation.