Efficient photodegradation of 2, 4-D by B-doped g-C3N4 nanosheets prepared by a two-step thermal polymerization method

The photocatalytic application of graphic carbon nitrate (g-C3N4) was limited due to the defects of few exposed active sites and serious recombination rate of photogenerated carrier. In this paper, boric acid-assisted thermal etching strategy is designed from melamine as precursor to realize nanosheets of B-doped porous g-C3N4 as high-performance photocatalyst and first applied to the mineralization and degradation of 2, 4-dichlorophenoxyacetic acid (2, 4-D) wastewater. Porous morphologies with increased specific surface area accelerate photocatalytic activity. It is noted that boron atoms were simultaneously doped into g-C3N4 matrix, which broke the symmetry of pristine g-C3N4, resulting in more effective separation of electron/hole pairs. Under simulated sunlight irradiation, the removal efficiency of 2, 4-D over this catalyst increased up to 94.9%. The degradation rate was maintained at 78.4% after four reuse cycles, indicating that the catalyst has decent stability. Based on gas chromatography-mass spectrometry analysis, degradation pathways were designed. The proposed synthesis strategy provides meaningful guidance for the industrial-scale production of high-performance g-C3N4 and its practical application in the environmental field.