Achieving efficient photocatalytic uranium extraction within a record short period of 3 min by Up-conversion erbium doped ZnO nanosheets

As an important strategic resource and environmental pollutant, uranium has high toxicity and economic value. Photocatalytic reduction of soluble hexavalent uranium (U(VI)) is a green and economic method to achieve uranium extraction, whereas the reported photocatalyst commonly requires a long period of > 1 h to reach a high extraction efficiency (>90%). Herein, we reported the ultrafast photocatalytic uranium extraction by up-conversion Er doped ZnO nanosheets. In the initial U(VI) concentration of 200 mg/L, the Er doped ZnO with 4% doping level (Er0.04-ZnO) nanosheets achieved 91.8% within 3 min, which was at least a magnitude shorter relative to ever-reported materials. The Er0.04-ZnO nanosheets reached a high removal efficiency of 96.1% in 10 min, with a considerable U(VI) extraction capacity of 3036 mg/g. The mechanistic study showed that the Er doping induced the up-conversion properties and increases the carrier density, thus enhancing the light adsorption and accelerating the U(VI) extraction.