Few-Layered Phosphorene–Graphitic Carbon Nitride\nNanoheterostructure as a Metal-Free Photocatalyst for Aerobic Oxidation\nof Benzyl Alcohol and Toluene

Abstract

Herein,\nwe have, for the first time, fabricated a few-layered phosphorene\n(FLP) and few-layered carbon nitride (FLCN) nanoheterostructure as\na metal-free and broad solar light-absorbing photocatalyst for highly\nselective conversion of primary C–H bond of toluene and benzyl\nalcohol to benzaldehyde in the presence of oxygen. The FLP–FLCN\nphotocatalyst can effectively oxidize benzyl alcohol to benzaldehyde\nwith superior selectivity (>99%) under the visible light irradiation\nconditions. Moreover, a conversion rate of 82.6 mmol/(g h) from toluene\nto benzaldehyde is achieved after 24 h of photoreaction. The fine\nstructural analysis including synchrotron-based X-ray absorption near-edge\nstructure and photoelectron spectroscopy and electrochemistry signifies\nthat the enhanced photocatalytic activity of FLP–FLCN is mainly\ncontributed from the synergistic electronic coupling at the FLP–FLCN\ninterface. The photogenerated hole–electron pairs and superoxide\nanion radicals play a crucial role in facilitating the C–H\noxidation reaction. In addition, the FLP–FLCN can be reused\nfor at least five cycles to efficiently photocatalytic conversion\nof benzyl alcohol without obvious loss of photocatalytic activity\nand microstructures. These findings provide a novel strategy to synthesize\na metal-free nanocatalyst for the visible-light-driven photocatalytic\nconversion of specific organic transformation with high selectivity\nand superior conversion rate.