Perylenetetracarboxylic diimide covalently bonded with mesoporous g-C3N4 to construct direct Z-scheme heterojunctions for efficient photocatalytic oxidative coupling of amines

Abstract

Photocatalytic oxidative coupling of amines is a promising method for imine synthesis. In this paper, a robust covalently-bonded direct Z-scheme heterostructure (PDI/mpgCN) for photocatalytic oxidative coupling of amine was reported for the first time. Perylenetetracarboxylic diimide (PDI) molecules were covalently connected to the surface of mesoporous carbon nitride (mpgCN) via an in-situ condensation strategy. Compared with the poor conversion efficiency upon pristine g-C3N4, PDI/mpgCN heterostructure exhibits a remarkable enhancement on amine oxidation rate (AOR), with the optimal AOR reaches to as high as 20.63 mmol g−1 h−1 upon 20 % PDI/mpgCN. As far as we know, it is the highest AOR achieved so far for amine photooxidation coupling with heterojunction materials. Transient absorption studies proved the formation of Z-scheme junction, and efficient interfacial charge transfer. Our study not only makes an insight into the heterojunction design with chemical bond precision, but highlights the great prospects of Z-scheme photocatalyst in photo-chemical synthesis.