The Impact of Polymerization Atmosphere on the Microstructure and Photocatalytic Properties of Fe-Doped g-C3N4 Nanosheets

Peroxymonosulfate (PMS, SO52−)-based oxidation is an efficient pathway for degrading organic pollutants, but it still suffers from slow degradation efficiency and low PMS utilization. In this work, we report the preparation of porous Fe-doped g-C3N4 catalysts by one-step thermal polymerization using urea and transition metal salts as precursors and investigate the effect of atmosphere conditions (air and nitrogen) on the catalytic performance. Systematic characterizations show that Fe-doped g-C3N4 prepared in air (FeNx-CNO) has a larger specific surface area (136.2 m2 g−1) and more oxygen vacancies than that prepared in N2 (FeNx-CNN, 74.2 m2 g−1), giving it more active sites to participate in the reaction. Meanwhile, FeNx-CNO inhibits the recombination of photogenerated carriers and improves the light utilization. The redox cycling of Fe(III) and Fe(II) species in the photocatalytic system ensures the continuous generation of SO5•− and SO4•−. Therefore, FeNx-CNO can remove CBZ up to 96% within 20 min, which is 3.4 times higher than that of CNO and 3.1 times higher than that of FeNx-CNN, and the degradation efficiency can still retain 93% after 10 cycles of reaction. This study provides an economical and efficient method for photocatalysis in the degradation of medicines in contaminated water.