In situ construction of a 2D/2D SnS2/MXene heterojunction for visible-light photocatalytic uranium reduction

Abstract

The photocatalytic reduction of soluble U(VI) into insoluble species presents a promising technique for removing radioactive uranium species from solution. The critical aspect in this field lies in the development of high-performance photocatalysts. Herein, a MXene (Ti₃C₂) and 2D SnS₂ nanosheet composite is synthesized by a one-step hydrothermal method. The as-synthesized SnS₂/MXene heterostructure can reduce 93% of U(VI) under visible light irradiation in 200 min, which is 25% higher than pure SnS₂. In addition, SnS₂/MXene exhibited high stability and can endure more than 6 photocatalytic cycles, with the removal ratio of U(VI) remaining above 84%. Based on XPS, UV-vis, and PL analyses, the construction of a SnS₂/MXene heterojunction not only improves the adsorption capability of visible light but also augments the efficiency of charge separation and transport. Additionally, DFT calculations further corroborate this enhancement mechanism by elucidating the formation of a built-in electric field between SnS₂ and MXene slabs.