Insights into the structural variation and photocatalytic performance of g-C3N4 via doping N, O and S atoms

Non-metal (N, O and S) doped g-C3N4 was successfully prepared via thermal polymerization of melamine and dopants and applied for photocatalytic degradation of tetracycline (TC). The structure and photocatalytic properties of N, O, S-doped g-C3N4 were comparatively investigated. The impacts of catalyst dosage, pollutant concentration, and co-existing anions and cations on the photocatalytic performance were also investigated in detail. The results showed that N was incorporated into the g-C3N4 matrix by forming graphitic nitrogen; O was incorporated into the skeleton by substituting the signals of the N atoms in N–C = N to form N–C–O bonds; and S formed C–S bonds by replacing the N atoms of the g-C3N4 matrix. Various techniques such as XPS, UV–Vis DRS, Mott-Schottky curves, transient photocurrent responses, EIS and PL have confirmed that O-doped g-C3N4 displayed the best photocatalytic performance of TC (87.6