A post-grafting strategy to modify g-C3N4 with aromatic heterocycles for enhanced photocatalytic activity

A novel and facile post-grafting strategy, instead of conventional copolymerization, via a Schiff base chemical reaction between aldehyde and -NH2 groups has been developed to construct aromatic heterocycle-grafted graphitic carbon nitride (g-C3N4) photocatalysts for the first time. The highresolution N 1s XPS spectrum and the CO2 TPD analysis confirmed the successful introduction of heterocycles and the reduced structural defects (unreacted -NH2 groups during the copolymerization modification of g-C3N4). The post-grafting of aromatic rings into the g-C3N4 network did not disrupt the original framework of g-C3N4, but effectively expanded its p-delocalized system, enlarged its surface area and promoted the separation and transfer of photo-excited charge carriers. As a result, the obtained copolymer composites exhibit significantly enhanced visible-light photocatalytic activity for H-2 evolution over pristine g-C3N4. This strategy is general and can be used to graft large numbers of aromatic rings of different molecular structures onto g-C3N4.