Boosting efficient U(VI) immobilization via synergistic Schottky heterojunction and hierarchical atomic-level injected engineering

Abstract

The graphical abstract shows the photoreduction mechanism of uranium-containing wastewater via TiOS/NHCS heterojunction. S injection facilitates the yields of photon-generated carries and Schottky junction inhibits recombination of electron-hole pairs. The active electrons reduce the U(VI) to U(IV), while the ethanol, as sacrificial agent deplete the holes. • The S injection engineers the energy level structure of TiO 2 . • Schottky junction optimizes the utilization of electron-hole pairs. • Such enhancements boost the photoreduction capacity of U(VI). • A high U(VI) removal ratio of more than 90% is achieved. Nuclear power has brought promising energy sources while laying down the potential risks for environmental friendliness. The technology that converting mobile U(VI) to immobilized U(IV) via photocatalytic reduction is considered to be an effective strategy for treatment spent fuel wastewater systems. Here we employed S-injected engineering to functionalize atoms in the TiO 2 /N-doped hollow carbon sphere (TiOS/NHCS) heterostructure to obtain exciting U(VI) removal efficiency. The experimental results suggested that the U(VI) reduction efficiency exceeded 90% in 20 min at a low initial concentration of 10 mg L -1 , and even the removal ratio per unit mass reached 448 mg. Density functional theory calculations further proved that the injected S-atoms optimized the energy level structure of TiO 2 and strengthened the light utilization ability. Additionally, the remarkable effect benefit forms the spatial separation of photogenerated electrons by the Mott-Schottky junction and the optimization of the TiO 2 energy-level structure by functionalized atoms. It is believed that this work will lay a foundation for the atomic functionalization of photocatalysts and the collaborative design of more advanced injection engineering and Schottky junction for enriching uranium-containing wastewater in the future.