Fabrication of oxygen doped g-C3N4 through the formation of a supramolecular precursor for the enhanced photocatalytic degradation of sulfonamides

BACKGROUNDGraphitic carbon nitrate (g-C3N4) is considered a promising metal-free photocatalyst. However, the applications of pristine g-C3N4 are subject to the high recombination of electron-hole pairs and low solar utilization. This study aimed to develop a unique and effective method to synthesize oxygen-doped g-C3N4 with enhanced photocatalytic activity for pollutant treatment.RESULTSOxygen-doped g-C3N4 photocatalysts (CN(M), CN(E), CN(I), and CN(P)) were successfully synthesized via the thermal polycondensation of a novel supramolecular precursor based on urea and monobasic alcohol, in which the urea and alcohol solvent can fully interact through a cross-linking network fabricated by H-bonding. The as-prepared catalysts exhibited enhanced catalytic activity compared with g-C3N4 on the photocatalytic oxidation of sulfanilamide antibiotics (SMR). The structure of alcohol has an influence on the amount of oxygen doping and on the catalytic activity of oxygen-doped g-C3N4; the optimized photocatalytic performance was achieved on CN(I). By combining characterization results, the improved catalytic activity was mainly ascribed to a certain amount of highly electronegative O atoms being doped into the tri-s-triazine units of g-C3N4, which can optimize the basic chemical structure, thus improving light-harvesting and increasing the separation rate of electron-hole pairs. In addition, trapping experiments indicated that & BULL;O-2(-) is the main active species in the photocatalytic degradation of sulfamethazine.CONCLUSIONThis work provides a facile and efficient approach for the fabrication of an O doped g-C3N4 catalyst with promising photocatalytic performance on SMR degradation. (c) 2022 Society of Chemical Industry.