Synergy of oxygen vacancies and thermoelectric effect enhances uranium(VI) photoreduction

Abstract

The conversion of soluble U(VI) to relatively immobilized U(IV) by photocatalytic techniques is considered to be the most effective method to prevent uranium contamination. Herein, a novel photocatalyst (TiO2−x/1T-MoS2) that combines photochemistry and thermoelectric physics is reported. The photocatalyst can use oxygen vacancies to briefly capture surrounding photogenerated electrons to improve the photogenerated carrier separation rate. Additionally, a large thermoelectric potential difference can be generated through a temperature gradient in the liquid environment, thereby changing the high-energy electron population on the substrate, and achieving the efficient capture of U(VI) species in extreme environments. The experimental results show that the TiO2−x/1T-MoS2 photocatalyst can remove more than 98% of U(VI) within 60 min without adding any sacrificial agent, and maintain a good U(VI) removal ratio even in a strong acid/base environment. This work will provide a reference for designing heterogeneous catalysts with both high catalytic activity and practicality for U(VI) photoreduction.