Nitrogen-doped carbon nanosheets for efficient degradation of bisphenol A by H2O2 activation at neutral pH values

Abstract

Metal-free carbonaceous materials exhibit great potentials as heterogeneous catalysts for Fenton-like degradation of organic pollutants, because of their high stability and free of secondary pollution of leaching metals. However, the low catalytic activity of carbonaceous materials toward H2O2 activation limits their applications. Herein, we report on a facile two-step thermal annealing method of preparing a kind of nitrogen-doped carbon nanosheets (NCN), which shows efficient degradation of bisphenol A (BPA) via H2O2 activation under neutral conditions. Almost 100% of BPA was removed in 30 min by NCN catalysts in the presence of 12 mmol/L H2O2 at neutral pH values. This NCN catalyst shows good stability with negligible activity decay during recycle use. The influencing factors including the H2O2 addition, NCN dosages, initial BPA concentration, and initial pH values to the removal of BPA by NCN were explored. The radical quenching experiment coupled with an electron spin resonance (ESR) spectrometer demonstrated that singlet oxygen (1O2), and superoxide radical (·O2–) served as primary active species for the pollutant degradation. Pyrrolic N served as adsorption active sites for BPA; Ketonic CO, unsaturated carbon bonds of CC and CC, and graphic C/N are supposed to be active sites for the catalytic reaction. This work provides a new sight in the preparation of carbon-based heterogeneous catalysts and their activation of H2O2 for the removal of organic pollutants from water.