Ultrafast Photoassisted Capture of Uranium over Cu2O/CuO Heterojunction Enabled by Rapid Interfacial Electron Transfer

Abstract

Photoassisted capture of uranium provides a promising strategy for the sustainable utilization of nuclear energy. Herein, we constructed Cu₂O/CuO heterojunctions in situ by a wet-etching method, showing ultrafast reaction kinetics and photocatalytic activity for U(VI) reduction. In 8 ppm of uranium-containing wastewater, the Cu₂O/CuO heterojunctions exhibited a remarkable uranium extraction efficiency of 94.6% within 10 min under irradiation, which exceeded most recently reported photocatalysts. The photocatalytic reaction rate constant of Cu₂O/CuO heterojunctions was 5.8-time larger than that of pure Cu₂O. A mechanism study indicated that the photogenerated electrons reduced CuO species in Cu₂O/CuO heterojunctions and in situ created the oxygen vacancy during the photocatalysis process, which strengthened the binding of UO₂²⁺. The rapid electron transfer rate over the in situ heterojunction interfaces and the enhanced UO₂²⁺ binding strength by the in situ formed oxygen vacancy accounted for the ultrafast reaction kinetics.