Rational construction of defective Z-Scheme tandem heterojunction interfacial charge transfer channels for efficient uranium collection and resistance to biological contamination

Designing an efficient reduction of soluble U(VI) to insoluble U(IV) is a challenge, and efficient electron-hole transfer efficiency is the key to the conversion of U(VI) to U(IV). Herein, defective transition metal sulfide (Ov-ZAF) Z-Scheme tandem heterojunctions with spatial separation were synthesized using an in situ self-assembly method. Ov-ZAF has excellent electron-hole separation, stabilized reactive active sites, and excellent visible light absorption. Ov-ZAF is able to realize the photocatalytic U(VI) reduction reaction (URR) and water oxidation reaction (WOR) synergistically. The results showed that Ov-ZAF was able to reduce 498.3 mg/g of U(VI) in 100 ppm uranium solution for 200 min, with a reduction efficiency of 99.8 %. Ov-ZAF showed excellent reduction ability in a variety of uranium-containing waste solutions as well as in real seawater. In addition, Ov-ZAF is capable of generating reactive oxygen radials (ROS) and has excellent antimicrobial activity against Escherichia coli, Staphylococcus aureus and Pseudoalteromonas xiamen. Oxygen vacancies and tandem components can tune both occupied and unoccupied orbitals near the Fermi level of Ov-ZAF. This work provides a possibility of efficient uranium reduction engineering through tunable compositions and electronic structures.