Visible-light induced electron-transfer in MoO3 QDs/g-C3N4 nanosheets for efficient photocatalytic reduction of U(VI)

Visible light-driven photocatalytic technology has become an effective method to remove U(VI) from wastewater. Herein, MoO3 quantum dots (MQDs) were prepared by a one-step oxidation method using molybdenum disulfide as the precursor. The MQDs were used to modify g-C3N4 nanosheet photocatalysts (MQDn-C3N4, where n represents the mass percentage of MQDs) to enhance the photocatalytic performance of g-C3N4 nanosheets. The morphology, chemical composition and optical properties of the MQDn-C3N4 composites were investigated by a series of characterization methods. The MQD3-C3N4 could remove 96.4% of U(VI) after 150 min of illumination, which was about 1.9 times that of g-C3N4. The MQD3-C3N4 samples had excellent stability and recyclability after five cycles. The possible mechanism of the photocatalytic process was proposed through radical trapping experiments and electron spin-resonance, in which the reduction of U(VI) is facilitated by photogenerated e– and •O2– radicals. The MQDn-C3N4 photocatalyst is expected to provide new concepts for the treatment of wastewater containing radionuclides.