Modeling Uranyl Adsorption on MoS₂/Mo₂CT Heterostructures Using DFT and BOMD Methods

Uranium-bearing wastewaters exert a great threat to the ecological environment due to its high radiotoxicity level. The designing and fabrication of novel adsorption materials can be promoted for radionuclide elimination from wastewater. In this work, results from density functional theory and Born-Oppenheimer molecular dynamics simulations are reported for the uranyl adsorption behavior on the MoS₂/Mo₂CT heterostructure in the gas phase and in an aqueous environment. Uranyl ions prefer to be adsorbed at deprotonated O sites on the Mo₂COH surface and S sites on the MoS₂ side of the heterojunctions, resulting in the formation of bidentate configurations. In addition to coordination interaction, H-bond and van der Waals interactions can also play an important role in binding configurations. More importantly, the oxidation state U(VI) can be reduced to U(V) and then to U(IV) caused by the strong reducibility of the Mo₂COH surface at room temperature, whereas the uranyl complex can move freely on the MoS₂ surface. However, the coordination number of U with respect to H₂O in the first hydration shell on the Mo₂COH surface remains unchanged and is found to be 3, which is similar to that on the MoS₂ surface. This work provides novel nanosorbents for the removal of uranyl from wastewater. The present viewpoint provides valuable mechanistic interpretations for uranyl adsorption and will give a supplement to the experimental research.