An electron delocalization with n-π∗ transitions of graphitic carbon nitride photocatalyst for visible-light-driven water decontamination.

Improving electron delocalization and optical absorption properties of graphitic carbon nitride (g-CN) is essential for enhancing the performance of photocatalytic wastewater treatment. Herein, an enhanced electron delocalization with activation n-π∗ electronic transitions of g-CN (TCN) by embedding electron-rich pyrimidine units into the g-CN skeleton was successfully fabricated. Experimental characterizations and density functional theory calculations demonstrated that the precise incorporation of pyrimidine units into the g-CN skeleton reduces the degree of overlap of positive and negative charge centers, enhances the delocalization of conjugate electrons, and facilitates carrier separation. Furthermore, this novel structure introduced additional n-π∗ electronic transitions, extending the light-absorbing edge beyond 700 nm. As a result, after 60 min of light irradiation, TCN exhibited the highest kinetic constant (0.0287 min) in the degradation of tetracycline, which was ∼3.8 times higher than that of pristine g-CN. In particular, the optimal antibacterial rate for Staphylococcus aureus reached 88.3% after 4 h of light exposure. These findings illustrate the remarkable potential of TCN in addressing antibiotic and microbial contamination in water.