Dual active sites of single-atom copper and oxygen vacancies formed in situ on ultrathin TiO2(B) nanosheets boost the photocatalytic dehalogenative C–C coupling synthesis of bibenzyl

Abstract

The combination of photocatalytic dehalogenation of halogenated aromatics and C–C coupling synthesis of valuable organics is an interesting method for the elimination of pollutants and synthesis of valuable chemicals. Herein, we present a green method for the photocatalytic dehalogenation of benzyl bromide and selective coupling synthesis of bibenzyl achieved on the dual active sites of single-atom Cu and surface oxygen vacancies (V_OS) generated in situ on ultrathin 2D-TiO₂(B) nanosheets. The experimental results show that single-atom Cu sites on ultrathin TiO₂(B) nanosheets can improve charge transfer and separation efficiency and stabilize V_OS formed in situ; the presence of V_OS not only improves light absorption capacity but also favors the adsorption of reactant benzyl bromide molecules. More importantly, the dual sites of single-atom Cu and adjacent V_OS form a solid frustrated Lewis pair, favor the adsorption of benzyl bromide molecules, activate the C–Br bond, and boost the C–C coupling synthesis of bibenzyl. This work provides a novel insight into photocatalytic C–C coupling through the synergistic effect of single-atom Cu and V_OS on ultrathin nanosheet photocatalysts.