Fabrication of g-C3N4-based conjugated copolymers for efficient photocatalytic reduction of U(Ⅵ)

[Display omitted] •Fabrication of thiophene modified g-C3N4 conjugated copolymers.•TICN show superior photocatalytic performance for U(Ⅵ) reduction and keep the reliability of good performance under sunlight.•The modulated electronic band structure of TICN enhanced photocatalytic reduction for U(Ⅵ).•The photoconversion process of uranium species and the reactive oxygen was systemically studied. The photocatalytic reduction of hexavalent uranium(U(Ⅵ)) is considered to be a preferred approach for uranium extraction from seawater and treatment of uranium-contained wastewater. In this paper, we constructed intramolecular electron-donors doped conjugated copolymers by integrating thiophene donors into graphitic carbon nitride (g-C3N4) skeleton to achieve efficient photocatalytic reduction of U(Ⅵ). Compared with pristine g-C3N4, thiophene doped samples exhibit excellent optical and electrical properties, resulting in the efficiency of U(Ⅵ) photocatalytic reduction, which is 1.83 times higher than that of g-C3N4. The effects of the doping amount of thiophene, initial uranium concentration, solution pH, on the U(VI) removal by thiophene doped samples were preliminarily investigated. To verify the performance of the catalyst under the actual application conditions, we tried to use sunlight instead of the light source of the experimental system. Besides, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to explore the reaction mechanisms.