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 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 (VO s) on TiO2 to promote H2 production coupled with selective oxidation of benzylamine is demonstrated. The optimized PdSA+C /TiO2 -VO photocatalyst containing Pd single atoms (SAs), clusters (C), and VO s exhibits much superior performance to those of TiO2 -VO and PdSA /TiO2 -VO counterparts. The production rates of H2 and N-benzylidenebenzylamine over PdSA+C /TiO2 -VO are 52.7 and 1.5 times those over TiO2 -VO , respectively. Both experimental and theoretical studies have elucidated the synergistic effect of Pd SAs, clusters, and VO s on TiO2 in boosting the photocatalytic reaction. The presence of Pd SAs facilitates the generation and stabilization of abundant VO 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 VO 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.