Experimental and Computational Study on U(VI) Sorption Mechanisms of Single-Layered Ti₃C₂T_<i>X</i> Nanosheets

Environmental contamination by U(VI) from radioactive wastewater has become a challenging concern in the development of nuclear energy. A highly efficient recovery of U(VI) from wastewater is essential for environmental remediation and can mitigate the depletion of conventional uranium resources. This study describes the synthesis of single-layered Ti₃C₂T_<i>X</i> nanosheets by chemical exfoliation using ultrasonography. The single-layered structure promoted a high sorption capacity of 3.20 mmol/g for U(VI) (distribution constant <i>K</i>_d > 10⁴ mL/g) and excellent selectivity in mine wastewater that contained numerous coexisting ions. Fragmentation of the Ti₃C₂T_<i>X</i> nanosheets from micron-scale to nanoscale upon uranyl sorption was detected by small-angle X-ray scattering and transmission electron microscopy. Extended X-ray absorption fine structure spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculations demonstrated that uranyl groups coordinated with the terminal -OH and -F on the surface of the Ti₃C₂T_<i>X</i> nanosheets. These findings provide imperative insights into the design and application of nanomaterials to effectively treat uranium-contaminated wastewater.