Facile synthesis of nitrogen-defective g-C 3 N 4 for superior photocatalytic degradation of rhodamine B.

Developing a new photocatalyst for fast and highly efficient organic dye degradation plays an essential role in wastewater treatment. In this study, a photocatalyst graphite phase carbon nitride (g-C 3 N 4 ) containing nitrogen defects (CN) is reported for the degradation of rhodamine B (RhB). The porous g-C 3 N 4 photocatalyst is facilely synthesized through a polycondensation method and then characterized by X-ray diffraction (XRD), infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), N 2 isotherm adsorption line, and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity of the g-C 3 N 4 is evaluated through the degradation of RhB under visible light irradiation. The results show that photocatalytic activity of the nitrogen-defective g-C 3 N 4 can be improved by optimizating washing conditions, including washing temperature, washing dosage, drying time, and drying temperature. With the prepared nitrogen-defective g-C 3 N 4 , decolourization of RhB is able to be completed within 20 minutes, in which the degradation rate is 1.7 times higher than that of bulk g-C 3 N 4 . Moreover, the nitrogen-defective g-C 3 N 4 has high stability and reusability in the degradation of RhB. Photocatalytic degradation mechanism investigations by ultraviolet-visible absorption spectroscopy, radical trapping experiments and high-performance liquid chromatography (HPLC) reveal that RhB achieved complete mineralization through the photocatalytic degradation reaction mediated by superoxide radicals (˙O 2 - ). This work thus provides a new approach for the preparation of photocatalysts for organic pollutants treatment in wastewater samples.