Construction of BiFeVO4/FeS integrated heterostructures for enhanced synergistic adsorption and photocatalysis reduction of U(VI) under visible light

The photocatalytic reduction of soluble U(VI) to insoluble U(IV) is an effective method for the treatment of uranium-containing wastewater. This study focuses on developing an efficient catalyst for the photocatalytic reduction of U(VI). Herein, FeS was synthesized by liquid-phase precipitation and modified onto BiFeVO 4 . The results demonstrated that the BiFeVO 4 -to-FeS mass ratio of 1:1 combined with a material aging time of 24 h (denoted as BiFeVO 4 /FeS-24) achieved the highest U(VI) reduction efficiency under visible light, which was mainly attributed to the adsorption and reduction of U(VI) by FeS, and the reduction of U(VI) by photo-induced electron and •O 2 − . Notably, the U(VI) removal efficiency of BiFeVO 4 /FeS-24 (84.3 %) was significantly higher that of BiFeVO 4 (9.1 %) and FeS (56.7 %) alone. The maximum U(VI) adsorption capacity of the material is 87.26 mg/g in the dark reaction stage, whereas its maximum U(VI) removal capacity reaches 301.2 mg/g under visible light. BiFeVO₄/FeS-24 maintains high removal efficiency even after five reuse cycles, indicating its high stability and excellent recyclability. The photocatalytic reduction mechanism of U(VI) by BiFeVO 4 /FeS-24 was elucidated through XPS, Mott-Schottky, EIS, I-t, and EPR. These analyses revealed that the excellent photocatalytic performance of BiFeVO 4 /FeS-24 in U(VI) removal stems from crystal structural integration and the formation of a Z -scheme heterojunction, which effectively narrows the band gap, enhances visible light absorption, and facilitates the separation of photogenerated electron-hole pairs. Overall, this study provided a simple approach for the effective removal of U(VI) from uranium-containing wastewater.