Fabrication of g-C3N4/Sn3O4/Ni electrode for highly efficient photoelectrocatalytic reduction of U(VI)

Removal of uranium from uranium-containing wastewater is of great significance for uranium contamination remediation and development of nuclear energy. In this paper, the g-C3N4/Sn3O4/Ni (CSN) electrode was fabricated and used as photoanode for photoelectrocatalytic reduction of U(VI) under visible LED light irradiation, and a photoelectrocatalytic approach was proposed to efficiently remove uranium from uranium-containing wastewater. The U(VI) was deposited as U(IV) at cathode and the removal rate of U(VI) reached 94.28 % at pH of 5.0 for photoelectrocatalytic approach, while the removal rates of U(VI) only amounted to 10.56 % and 36.65 % for the photocatalytic and electrochemical extraction approaches, respectively. Furthermore, the photoelectrocatalytic reduction mechanism for U(VI) is explored by XPS, EIS, PL, EPR and DFT calculations, which indicated that the excellent photoelectrocatalytic performance of CSN electrode for U(VI) is mainly because it enhanced visible light absorption, promoted separation of photogenerated electron-hole pairs and decreased the band gap. This work provided a facile route for efficient removal of U(VI) from uranium-containing wastewater via photoelectrocatalytic method.