Efficient photodegradation of micropollutants by tubular carbon nitride: The role of nitrogen defects

Defect chemistry possessed the significant effect for the performance of heterogeneous photocatalysts, so the construction of defect structures in photocatalysts has attracted attention. In this paper, tubular g-C₃N₄ (TCN) with an excellent specific surface area was obtained by morphological regulation, and the defect chemistry in TCN and its photocatalytic mechanism were explored. The elemental composition and chemical states verified the formation of nitrogen defects during preparation process, and the nitrogen defects would adjust the electronic and band structures of TCN according to the results of density functional theory calculation, resulted in its excellent optical properties. The photocatalytic activity of the obtained TCN was evaluated through the elimination of some typical micropollutants. The results indicated that more than 90% of micropollutants could be degraded after 30 min visible light exposure, and TCN still maintained superior photocatalytic performance after reuse. Meanwhile, the oxygen adsorption model also indicated that the nitrogen defect would promote the adsorption of dissolved oxygen on TCN to produce ·O₂^-, which acted as the main reactive oxygen species during atrazine degradation process. Finally, the toxicity of treated solution and intermediates were proved to be reduced by the bioluminescence inhibition tests and Ecological Structure Activity Relationships (ECOSAR) software.