Regulating exciton dissociation and charge carrier behavior of graphitic carbon nitride via 3,9-perylenedicarboxylic acid for efficient photocatalytic hydrogen evolution

Abstract

Graphitic carbon nitride (GCN) is one kind of promising photocatalyst for its low cost and stable property. However, deficient light absorption capacity and charge transfer driving force hinders its further application. In this work, 3,9-perylenedicarboxylic acid (PA) has been introduced into GCN during thermal polymerization process to form a new photocatalyst and then applied in photocatalytic hydrogen evolution. By doping 0.1 wt% PA, the optimized photocatalyst shows a hydrogen evolution rate up to 1.47 mmol·g-1·h-1. The apparent quantum efficiency reaches 1.36 % at 420 nm for the optimized catalyst. The photophysics characterizations indicate that the prepared PAX-GCN enlarges light response in visible region and promotes charge transfer process. According to DFT calculation results, spatially separated LUMO and HOMO have been obtained by grafting PA on GCN, which provides proof for intramolecular charge transfer and explanation for improved charge separation. Moreover, the modified photocatalyst exhibits good operational stability without obvious decay over 5 cycles.