Spatial separation of dual-cocatalysts on bismuth vanadate for selective aerobic oxidation of benzylalcohols to benzaldehydes under visible light irradiation

Abstract

The selective conversion of alcohols to aldehydes under ambient conditions using semiconductor-based photocatalysts has attracted more and more attention in organic synthesis. In this work, bismuth vanadate (BiVO₄) crystals with spatially separated dual-cocatalysts on different facets were introduced as photocatalysts for aerobic oxidation under visible light. It was found that the photocatalytic conversion of benzylalcohols to benzaldehydes was remarkably enhanced when Pt and MnO_x are selectively deposited on the {010} and {110} facets of the BiVO₄ crystal, acting as reduction and oxidation cocatalysts, respectively. The superior performance could be attributed to the spatial separation of the reduction and oxidation reactions so that the recombination and reverse reactions are greatly inhibited. We also found that adding a small amount of H₂O in the system to increase the solubility of the photocatalysts at the interface of water and oil can remarkably boost the reaction rate of aerobic oxidation. Our work shows a useful strategy for the rational design and construction of highly efficient photocatalyst systems for the synthesis of organic compounds via photocatalytic processes.