A Defect-Induced In Situ Phosphorylation Strategy of Molybdenum Disulfide: Structural Modification and Uranium Adsorption Performance Enhancement

The development of superior adsorbents that can achieve efficient, fast, and highly selective U(VI) separation for practical applications remains a challenge. MoS₂ has great potential for U(VI) adsorption owing to its two-dimensional layered structure and abundant active sulfur sites. Herein, a novel few-layered Pd-MoS₂-PO₄ with high-density marginal sulfur and phosphoric group active sites was synthesized by using a combined strategy involving molten salt electrolysis and defect-induced in situ phosphorylation. By adjusting the in situ Pd and phosphoric acid concentrations, the phosphoric group concentration and the corresponding adsorption activity can be controlled. 0.5Pd-MoS₂-PO₄ nanosheets exhibit ultrafast adsorption (equilibrium is reached within only 3 min) and ultrahigh adsorption capacity (416.62 mg/g), surpassing those of most previously reported modified MoS₂ and other materials. Moreover, the adsorption process is best fitted with the pseudo-second-order kinetic model and Langmuir isotherm model, indicating the occurrence of heterogeneous chemisorption. 0.5Pd-MoS₂-PO₄ exhibits ultrahigh selectivity to U(VI) (selective adsorption capacity (<i>S</i>_U) > 59.1%). The excellent adsorption properties of 0.5Pd-MoS₂-PO₄ are closely related to its unique structural characteristics, including a large surface area, abundant porosity, excellent chemical stability, and high-density, marginal sulfur, and phosphoric group active sites. Furthermore, 0.5Pd-MoS₂-PO₄ is well suited for highly efficient and selective U(VI) recovery from radioactive wastewater, indicating its potential for practical applications.