Enhancing photocatalytic performance by direct photo-excited electron transfer from organic pollutants to low-polymerized graphitic carbon nitride with more C-NH/NH2 exposure

Abstract

Abstract A partially low-polymerized g-C3N4 (LCN) has been successfully prepared via a two-step treatment, in which the basic skeleton of g-C3N4 is preserved with more C NH/NH2 exposure. Density functional theory (DFT) calculations indicate that the exposure of C NH/NH2 groups not only introduces an acceptor impurity level, but also strengthens the adsorption interaction between pollutants and LCN by fostering stronger π-π interactions between the aromatic ring of BPA and the N atom in C N C of LCN. Based on the results of UV–vis diffuse reflectance spectra, electron paramagnetic resonance spectra and transient photocurrent response spectra, the adsorbed organic pollutant creates a donor impurity level in the energy band of LCN, endowing LCN with efficient light-harvesting properties. Therefore, in addition to pollutant degradation by HO2 /O2 −, the direct photo-excited electron transfer from pollutant molecules to conduction band/acceptor impurity level of LCN under visible-light irradiation further enhances the photocatalytic pollutant degradation performance compared with bulk g-C3N4.