A simple process to prepare few-layer g-C3N4 nanosheets with enhanced photocatalytic activities

Abstract

Graphitic carbon nitride (g-C3N4) nanosheets with few-layer and single-layer structures were prepared by a simple chemical exfoliation method. The samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, UV–vis absorption spectroscopy and photoluminescence spectroscopy, respectively. The investigations indicated that the bulk g-C3N4 can be easily exfoliated into g-C3N4 nanosheets with few-layer structure under the assistance of HNO3. The specific surface area of few-layer g-C3N4 reached 179.5m2g−1, which was about 10.3 times higher than that of bulk g-C3N4 (17.4m2g−1). The absorption edge of few-layer g-C3N4 nanosheets showed a blue shift from 486nm to 458nm, corresponding to an increase in the band gap from 2.55eV to 2.70eV compared with that of bulk g-C3N4. In addition, the position of the emission peak of few-layer g-C3N4 was blue shifted from 461nm to 439nm. The photocatalytic performance of samples was evaluated by the degradation of methylene blue and the photocatalytic water splitting under visible light irradiation. The experimental results indicated that the degradation rate of MB on few-layer g-C3N4 nanosheets was about 1.3 times higher than that of bulk g-C3N4, the H2 production rate reached 110.68μmolg−1h−1 over g-C3N4 nanosheets, which was 1.22 times higher than that of bulk g-C3N4.