Enhanced photocatalytic uranium(VI) removal via oxygen vacancy-assisted Z-scheme SPC-Bi/Bi2WO6 with plasmonic Bi activation

Efficient removal of uranium from wastewater is crucial for environmental safety. Herein, we report a multifunctional Z -scheme heterojunction photocatalyst (SPC–Bi/ Bi 2 WO 6 ) synthesized by anchoring plasmonic Bi/Bi 2 WO 6 —with integrated plasmonic effects and semiconductor properties—onto a starch phosphate carbon (SPC) substrate. The synergistic interplay of localized surface plasmon resonance (LSPR) and oxygen vacancies significantly enhances light harvesting, charge separation, and U(VI) reduction. The LSPR effect of Bi under visible light irradiation generates hot electrons and lowers the semiconductor energy barrier, while the oxygen vacancies in SPC act as electron traps to prolong carrier lifetimes. A Z -scheme heterojunction formed at the SPC-Bi/Bi 2 WO 6 interface promotes directional charge transfer and suppresses recombination, enabling efficient photocatalytic U(VI) reduction. The SPC-Bi/Bi 2 WO 6 composite exhibited a high theoretical uranium removal capacity of 1245.3 mg g −1 and excellent selectivity ( K d = 2.84 × 10 4 mL g −1 ), removing 95.3% of U(VI) from real lake water. The composite maintained over 90% performance after six reuse cycles and displayed strong resistance to salinity and competing ions. This work offers a promising strategy for developing low-cost, sustainable photocatalysts for uranium remediation in complex aqueous environments.