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

Abstract

Herein, we have, for the first time, fabricated a few-layered phosphorene (FLP) and few-layered carbon nitride (FLCN) nanoheterostructure 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.