Heterostructure of anatase-rutile aggregates boosting the photoreduction of U(VI)

Abstract

The photoreduction of uranium over TiO2 provides an important pathway to uranium resource utilization and pollution abatement. However, the impact of the TiO2 crystalline type on photocatalytic reduction of U(VI) is still unclear. In this study, the influence of crystal type of TiO2 on U(VI) photoreduction was studied. The results showed that rutile was more reactive for the photocatalytic reduction of U(VI) than anatase. Interestingly, an obvious synergistic effect was observed for mechanically mixed rutile-anatase and the photoconverted UO2 particles preferred to precipitate on rutile surface. The optimum efficiency was achieved for the mixture containing 30 wt% anatase and 70 wt% rutile. The anatase {101} planes tended to match up with rutile {110} facets after the two minerals were mixed. The formation of rutile-anatase aggregates led to the transfer of photogenerated electrons from anatase to rutile. This process could prolong the lifetime of carriers, facilitating U(VI) reduction.