Facile bottom-up preparation of Cl-doped porous g-C3N4 nanosheets for enhanced photocatalytic degradation of tetracycline under visible light

•This work provides a facile bottom-up strategy for improving the performance of CN.•The doping of Cl element is helpful to promote the rapid separation of CN excited electrons from holes.•The prepared CN-Cl samples have larger specific surface area than pure CN. Utilizing highly efficient and stable photocatalysts to treat residual antibiotic pollutants in water is of great significance. In this work, Cl-doped porous g-C3N4 (CN-Cl) was prepared by a facile bottom-up synthetic route for photocatalytic degradation of tetracycline (TC). The synthesized samples were analyzed by a series of characterization methods. The optimum photocatalytic activity under visible-light irradiation for CN-Cl with the precursor mass ratio of ammonium chloride to melamine is 1:1 (92% degradation within 120 min), which is up to 2.4 times as high as that of pure CN. The remarkable improvement of the photocatalytic activity of CN-Cl is mainly due to the following three reasons: (i) Cl-doped element can help to regulate the electronic structure of CN; (ii) the prepared CN-Cl samples have larger specific surface area than pure CN, thus providing more reactive sites; (iii) Cl-doped element can inhibit the recombination of photo-induced electron and holes of CN. This work may provide a facile bottom-up strategy to improve the photocatalytic performance of CN for the mitigation of environmental problems.