Exciton dissociation and electron transfer behavior of a novel Donor-Acceptor g-C3N4 organic semiconductor photocatalytic separation of uranium

Photocatalytic uranium extraction from nuclear effluent is a promising method to avoid environmental damage and recover uranium resources. Here, the hollow tubular D-A organic semiconductor photocatalyst was fabricated by grafting 2,7-dibromo carbazole (Dbc) onto the g-C3N4 (TCN) framework. The intra-molecular D-A system promoted visible light absorption, enhanced charge transfer, and improved the separation of photogenerated electron-hole pairs. Additionally, the incorporation of the carbazole structure increased the volume separation and the surface separation, adjusted the electron excitation model, and reduced the energy required for exciton dissociation. The results showed that the removal rate of U(VI) by DCN3 reached 96.4% in 120 min and 93.3% removal of U(VI) under sunlight, and it was stable and reusable with little change under sunlight and after 5 consecutive cycles. Therefore, the D-A photocatalyst established a high photocatalytic uranium separation efficiency under sunlight and high concentrations of interfering anions and cations. This study provides insight and guidance for a deeper understanding of photocatalytic uranium separation.