Nitrogen deficient carbon nitride for efficient visible light driven tetracycline degradation: a combination of experimental and DFT studies

Abstract

The narrow visible-light absorption range and a high recombination rate of photo-excited electrons and holes are the main reasons for the confined photocatalytic performance of graphitic carbon nitride (g-C₃N₄). Here, g-C₃N₄ samples with nitrogen vacancies were synthesized with a very basic thermal polymerization method, and the resultant nitrogen deficient g-C₃N₄ (g-C₃N₄-1.0) prepared by adding 1 g NaOH exhibited better activity than original g-C₃N₄ for tetracycline degradation, because of a lower recombination rate of photo-excited charge carriers and a redshift of the light absorption range. The advances were confirmed by experiments and spin-polarized density functional theory (DFT), which corroborated each other and showed the effect of defect sites on g-C₃N₄-1.0 by investigating the electronic structure evolution of the system. The sample can be used for tetracycline degradation, and the spin-polarized DFT study helps understand the reaction mechanism.