Few-Layered Phosphorene-Graphitic Carbon Nitride Nanoheterostructure as a Metal-Free Photocatalyst for Aerobic Oxidation of Benzyl Alcohol and Toluene

摘要

Herein, we have, for the first time, fabricated a few-layered phosphorene (FLP) and few-layered carbon nitride (FLCN) nano-heterostructure as a metal-free and broad solar light-absorbing photocatalyst for highly selective conversion of primary C-H bond of toluene and benzyl alcohol to benzaldehyde in the presence of oxygen. The FLP-FLCN photocatalyst can effectively oxidize benzyl alcohol to benzaldehyde with superior selectivity (>99%) under the visible light irradiation conditions. Moreover, a conversion rate of 82.6 mmol/(g h) from toluene to benzaldehyde is achieved after 24 h of photoreaction. The fine structural analysis including synchrotron-based X-ray absorption near-edge structure and photoelectron spectroscopy and electrochemistry signifies that the enhanced photocatalytic activity of FLP-FLCN is mainly contributed from the synergistic electronic coupling at the FLP-FLCN interface. The photogenerated hole-electron pairs and superoxide anion radicals play a crucial role in facilitating the C-H oxidation reaction. In addition, the FLP-FLCN can be reused for at least five cycles to efficiently photocatalytic conversion of benzyl alcohol without obvious loss of photocatalytic activity and microstructures. These findings provide a novel strategy to synthesize a metal-free nanocatalyst for the visible-light-driven photocatalytic conversion of specific organic transformation with high selectivity and superior conversion rate.