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

Abstract

BACKGROUND Graphitic 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. RESULTS Oxygen‐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 •O2− is the main active species in the photocatalytic degradation of sulfamethazine. CONCLUSION This work provides a facile and efficient approach for the fabrication of an O doped g‐C3N4 catalyst with promising photocatalytic performance on SMR degradation. © 2022 Society of Chemical Industry.