Preparation of water-dispersible porous g-C3N4 with improved photocatalytic activity by chemical oxidation

Abstract

Hydrophilic treatment of bulk graphene-like carbon nitride (g-C₃N₄) for future applications has aroused extensive interest, due to its enhanced specific surface area and unusual electronic properties. Herein, water-dispersible g-C₃N₄ with a porous structure can be obtained by chemical oxidation of bulk g-C₃N₄ with K₂Cr₂O₇–H₂SO₄. Acid oxidation results in the production of hydroxyl and carboxyl groups on its basal plane and the formation of a porous structure of g-C₃N₄ at the same time. The porous g-C₃N₄ appears as networks with tens of micrometers in width and possesses a high specific surface area of 235.2 m² g⁻¹. The final concentration of porous g-C₃N₄ can be up to 3 mg mL⁻¹. Compared with bulk g-C₃N₄, the as-obtained porous g-C₃N₄ exhibits excellent water dispersion stability and shows great superiority in photoinduced charge carrier separation and transfer. The photocatalytic activities of porous g-C₃N₄ towards degradation of organic pollutants are much higher than those of the bulk due to the larger band gap (by 0.2 eV) and specific surface areas.