Layered MoB MBene integrated with CdS for rapid visible-light-driven photocatalytic reduction of U(VI)

The photocatalytic reduction of soluble U(VI) to insoluble U(IV) stands out as a viable strategy for sustainable uranium-contaminated water treatment. However, the development of efficient, robust photocatalysts remain challenging. Here, we fabricate a layered MBene (MoB) coupled with CdS to form a robust nanocomposite that enables rapid visible-light-driven reduction of U(VI). The 5%MoB/CdS composite achieves 97.4% U(VI) removal within 10 min without sacrificial agents, displaying fast apparent kinetics, strong tolerance to common coexisting ions, and excellent cyclic stability. Radical-trapping experiments and electron spin resonance (ESR) measurements indicate that photogenerated electrons and superoxide radicals (·O₂⁻) are the primary active species driving U(VI) reduction. Kelvin probe force microscopy (KPFM) and femtosecond time-resolved transient absorption spectroscopy (fs-TAS) directly reveal enhanced interfacial charge transfer and prolonged carrier lifetime. Density functional theory (DFT) calculations reveal favorable band alignment and the formation of a Schottky barrier at the MoB/CdS interface, which directs electron transfer from CdS to the highly conductive layered MoB and suppresses charge recombination. The outstanding performance originates from the high conductivity and abundant active sites of sheet-like MoB, which facilitate electron extraction and offer numerous reduction sites. This work introduces a strategy for constructing highly efficient MBenes-based photocatalysts for uranium remediation.