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 m(2) 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.

Room-temperature synthesis of nanoporous 1D microrods of graphitic carbon nitride (g-C3N4) with highly enhanced photocatalytic activity and stability

“…The characteristic peaks for the acid-treated samples were similar to those of the bulk structure, indicating that g-C 3 N 4 had the same chemical composition even after exfoliation and conversion of the morphology. The many small peaks observed in the range of 1200–1650 cm −1 correspond to stretching vibrations of C=N, C–NC–C or C–N–C bonds of C–N heterocycles4950. The presence of these bands confirmed that the basic surface functional units were retained after the acid and thermal treatments.…”

Oxygenated monolayer carbon nitride for excellent photocatalytic hydrogen evolution and external quantum efficiency

“…43,44 In contrast, the peak corresponded to C-OH became much stronger for the O-g-C 3 N 4 monolayer (532.1 eV), suggesting that more C-OH groups were generated in O-g-C 3 N 4 monolayer after the oxidation cutting. Beside the O 1s peak at 532.1 eV, a new peak at 533.0 eV has been detected, which refers to the O=C.…”

Hydrogen production and photocatalytic activity of g‐C3N4/Co‐MOF (ZIF‐67) nanocomposite under visible light irradiation

“…The FTIR spectra of the bare g‐C 3 N 4 show that the broad peak from 3274 cm −1 to 3078 cm −1 is the corresponding stretching modes of N‐H bonds . The small bumps in the range of 1200 cm −1 ‐1650 cm −1 related to stretching vibrations of (C=N, C‐NC‐C or C‐N‐C bonds) CN heterocycles A tiny peak at 878 cm −1 was matching to the stretching mode of the N‐O group . The sharp peak observed at 806 cm −1 assigned to the breathing modes of triazine units .…”