Electronic interaction and oxygen vacancy engineering of g-C_(3)N_(4)/α-Bi_(2)O_(3) Zscheme heterojunction for enhanced photocatalytic aerobic oxidative homo-/hetero-coupling of amines to imines in aqueous phase

Photocatalytic oxidation coupling of amines represents a green and cost-effective method for the synthesis of highly value-added imines under visible light irradiation.However,the catalytic efficiency was severely limited by poor visible light response and easy recombination of photogenerated charge carriers.Herein,we report a g-CgN_(4)/α-Bi_(2)O_(3)Z-scheme heterojunction via electrostatic self-assembly of g-C_(3)N_(4)nanosheets and oxygen-va-cancy-rich aα-Bi_(2)O_(3)microsphere for visible-light driven oxidative coupling of amines to imines in H_(2)0 as green solvent at room temperature.Amines with diverse functional groups were efficiently converted into the corre-sponding imines in good to excellent yields.Impressively,this photocatalytic protocol is applicable for the challenging hetero-coupling of two structurally different amines to construct complicated asymmetric imines,which is the first report of photocatalytic hetero-coupling of amines to imines to our knowledge.Furthermore,the Z-scheme heterojunction also demonstrated high stability and could be readily separated and reused without obvious decay in activity and selectivity.Comprehensive characterizations and control experiments reveal the construction of Z-scheme heterojunction with intimate interface between g-CgN4 and a-Bi_(2)O_(3)greatly boosts the transfer and separation of photogenerated charge carries and enhances the redox capability.Meanwhile,the surface oxygen vacancies in a-Biz_(2)O_(3)also benefits the separation of photogenerated charge carriers and acti-vation of reactants.These jointly contributed to an enhanced photocatalytic performance for oxidative coupling of amines to imines.