Ultrafast recovery of aqueous uranium: Photocatalytic U(VI) reduction over CdS/g-C3N4

Abstract The photocatalysis can be used as an effective strategy for separating aqueous uranium. However, the low reaction efficiency of the photocatalytic system in open air strongly restrained its practical application. In this study, CdS/g-C3N4 nanocomposites were developed for reducing U(VI) under visible-light. Remarkably high photocatalytic efficiency was realized without the aid of any electron sacrifice, where uranyl was reduced to U(IV) only within 6 min, being the fastest among the ever-reported researches. CdS/CN-33 showed an optimal reaction rate of 0.641 min−1, being 9.67 and 64.10 times of that for pristine CdS and g-C3N4, respectively. Most importantly, a satisfying performance was achieved for the photocatalytic U(VI) reduction in open air, as well as under solar irradiation and a 4 W LED lamp. The extraction capacity for uranium reached 2,379 mg/g, and the recycled CdS/g-C3N4 nanocomposites could keep high stability and activity.