Improving photocatalytic selective coupling amine and alcohol over single-unit-cell Pd/BiVO4 nanosheets by surface synergistic effect

Abstract

The single-unit-cell Pd/BiVO4 nanosheets are successfully prepared as the photocatalysts for the selective oxidative coupling of benzylamine (BZ) and benzyl alcohol (BA) to N-benzylidenebenzylamine (BZA) under visible light irradiation with an air atmosphere. Pd0.5/BVONS shows a high conversion (95.7%) of benzylamine and selectivity (98.9%) of N-benzylidenebenzylamine. The results of XPS and EPR suggest that abundant oxygen vacancies and low-coordinated metal atoms are exposed on the surface of BVONS. The result of in situ FT-IR reveals that BA molecules could be activated on BVONS surface via a -C-O···M (Bi and V) coordination, leading to the activation of α-carbon, thus enhancing the conversion of BA. The photogenerated electrons would be transferred to Pd nanoparticles via the Schottky junction for improving the separation of photogenerated electrons-holes, thereby accelerating the generation of ∙O2−. Finally, a possible mechanism is proposed for understanding the photocatalytic selective oxidative coupling of BZ and BA to BZA over the Pd0.5/BVONS. The synergism of each active sites on Pd0.5/BVONS achieves high photocatalytic efficiency. This work may offer an effective strategy to design photocatalysts for organic synthesis.