Novel carbon and defects co-modified g-C3N4 for highly efficient photocatalytic degradation of bisphenol A under visible light.

Graphite carbon nitride (g-C3N4, CN) is considered as a promising semiconductor for environmental catalysis. However, pure CN can not meet the requirements for actual applications due to its high recombination rate of photogenerated electron-hole pairs and a relatively large band gap preventing full utilization of solar energy. In this work, we report synthesis of a novel carbon and defects co-modified g-C3N4 (CxCN) by calcination of melamine activated by oxalic. This new catalyst CxCN has porous structure with much higher surface areas compared with pristine CN. UV-vis analysis and DFT calculations show that CxCN has a lower bandgap for enhancing visible light adsorption compared with CN. Photoluminescence (PL) and photoelectrochemical analyses show that CxCN has a low recombination rate of photogenerated electron-hole pairs, which improves the utilization of solar energy. As a result, CxCN samples show high efficiency for the degradation of bisphenol A (BPA) under visible light irradiation, where the best catalyst of CxCN (C1.0CN) samples shows about 22 times higher photocatalytic degradation rate than that of CN. Moreover, C1.0CN shows high mineralization rate and can degrade BPA into CO2 and H2O by the generated active species, like superoxide radicals (O2-) and holes (h+).