Acid-induced tubular g-C₃N₄ for the selective generation of singlet oxygen by energy transfer: Implications for the photocatalytic degradation of parabens in real water environments

Parabens are widely present in aquatic environments and pose potential health risk. Although great progress has been made in the field of the photocatalytic degradation of parabens, the powerful Coulomb interactions between electrons and holes are the major limitations to photocatalytic performance. Hence, acid-induced tubular g-C₃N₄ (AcTCN) was prepared and applied for the removal of parabens from a real water environment. AcTCN not only increased the specific surface area and light absorption capacity, but also selectively generated ¹O₂ via an energy transfer-mediated oxygen activation pathway. The ¹O₂ yield of AcTCN was 11.8 times higher than that of g-C₃N₄. AcTCN exhibited remarkable removal efficiencies for parabens depending on the length of the alkyl group. Furthermore, the rate constants (k values) of parabens in ultrapure water were higher than those in tap and river water because of the presence of organic and inorganic species in real water environments. Two possible pathways for the photocatalytic degradation of parabens are proposed based on the identification of intermediates and theoretical calculations. In summary, this study offers theoretical support for the efficient enhancement of the photocatalytic performance of g-C₃N₄ for the removal of parabens in real water environments.