The Effect of g-C3N4 in Its Composite With Cu-Cu2O on the Catalysis of Aerobic Oxidation of Benzylic Alcohols

In this work, the preparation and characterization of a composite of Cu-Cu₂O with g-C₃N₄ and its application in the catalysis of aerobic oxidation of benzylic alcohols are reported. The composites Cu-Cu₂O/g-C₃N₄ were prepared starting with CuSO₄ under reduction conditions with ball milling, followed by thermal treatment. The introduction of g-C₃N₄ into the composite can enhance the catalytic oxidation. Band structure analysis based on UPS data reveals that the enhancement can be attributed to the small work function of g-C₃N₄, which raises the VBM level of the chief catalyst Cu₂O through injecting electrons into the oxide at the heterojunction due to Fermi energy alignment. Both VBM ascending and forming an internal electric field (IEF) due to the electron transfer across the interface contribute to the enhancement in the catalysis. Further, the N-rich matrix g-C₃N₄ promotes proton transfer in the catalysis due to its basicity, which also accelerates the catalysis.