A novel graphitic carbon nitride photocatalyst with ultramicro amounts of intramolecular donor-acceptor structures for excellent photocatalytic hydrogen production

Abstract

In this study, facile supramolecular thermal polymerization was employed for an attempt to modify graphitic carbon nitride (g-C3N4) using ultramicro amounts of diphenylamino-4-benzaldehyde as the dopant, and melamine and cyanuric chloride as the raw materials. The reaction of aldehyde-amine achieved diphenylamino-4-benzaldehyde grafting onto the edge of the heptazine ring of g-C3N4, resulting in the formation of a novel g-C3N4 with intramolecular twisted donor–acceptor (D-A) structures known as CN-Dxmg. It was confirmed that addition of 2 mg (0.67 wt‰) of diphenylamine-4-benzaldehyde as the donor regulated the energy level distribution of CN-D2mg, and as-obtained intramolecular D-A structures can promote the photogenerated carrier separation and migration of CN-D2mg through a directional channel for electron transfer from diphenylamine-4-benzaldehyde to heptazine. The results indicate that CN-D2mg photocatalyst has a high hydrogen production rate of 14581.1 μmol·h−1·g−1 at 420 nm under visible light irradiation, which is 1.6 times higher than that of pristine g-C3N4. The study presents an effective approach for large-scale applications involving g-C3N4 photocatalyst in clean energy production.