Novel nitrogen-rich g-C3N4 with adjustable energy band by introducing triazole ring for cefotaxime removal

Graphitic carbon nitride (g-C3N4) possesses promising photocatalytic abilities due to its graphene-phase framework, distinct electronic structure, and optical performance. Nevertheless, the low visible light absorption capacity, rapid photoexcited electron-hole pairs recombination and transient electron lifetime have limited its extensive applications. In this study, nitrogen-rich triazole ring was introduced into conventional g-C3N4 structure to yield N-rich g-C3N4 (g-C3N4-N). Compared to traditional g-C3N4, the photocatalytic degradation efficiency of g-C3N4-N towards cefotaxime (CFX) was improved by 3-fold. Meanwhile, the mineralization rate rose to 51.3% with respect to 29.2%. The photocatalytic mechanism was then analyzed by various techniques, such as XPS, elemental analysis, FT-IR, and DFT calculations. The data revealed that introduction of triazole ring with mild electrophilicity on LUMO shifted the electron from melem to triazole ring. The change in electron structure shortened the bandgap of the catalyst and produced midgap state, thereby increasing the visible light absorption region of the catalyst. The PL, photocurrent density and EIS analyses suggested that midgap state could temporarily capture electrons and promote the separation of photoexcited electron-holes. In sum, the proposed novel one-step synthetic route of modified g-C3N4 material looks promising for future environmental remediation applications.