Despite that two-dimensional transition metal carbides and carbonitrides (MXenes) are burgeoning candidates for remediation of environmental pollutants, the construction of robust functionalized MXene nanosheets with a high affinity for target heavy metal ions and radionuclides remains a challenge. Here we report the successful placement of amidoxime chelating groups on Ti 3 C 2 T x MXene surface by diazonium salt grafting. The introduction of amidoxime functional groups significantly enhances the selectivity of Ti 3 C 2 T x nanosheets for uranyl ions and also greatly improves their stability in aqueous solution, enabling efficient, rapid, and recyclable uranium extraction from aqueous solutions containing competitive metal ions. Benefiting from the excellent conductivity of MXenes, the amidoxime functionalized Ti 3 C 2 T x nanosheets show outstanding electrochemical performance such that when loaded on carbon cloth the application of an electric field increases the uranium adsorption capacity from 294 to 626 mg/g, outperforming all organic electrochemical sorption materials reported previously. The present work provides an effective strategy to functionalize MXene nanosheets with fundamental implications for the design of MXene-based selective electrosorption electrode materials. Figure 2. XPS spectra of Ti 3 C 2 T x nanoflakes before and after grafting. High-resolution O 1s region of (a) TC and (b) G-TC and N 1s region of (c) G-TC and (d) F-TC.
This work presents the electrochemical behaviors of U on a liquid Bi electrode and the formation of Bi-U intermetallic compounds in LiCl-KCl eutectic. It was found that the deposition of U on the liquid Bi electrode was a two-step process. The activity coefficient of U in the liquid Bi was determined by coulometric titration and in-situ open circuit chronpotentiometry versus two different reference electrodes at the temperature range of 723 to 813K. The solubility of U in liquid Bi was evaluated by pulse electrolysis. Furthermore, thermodynamic properties of Bi-U intermetallic compounds were measured by open circuit chronopotentiometry. The linear dependence of the Gibbs free energy of formation as a function of temperature was obtained, from which the enthalpy and entropy of formation were also determined. The activities and partial molar Gibbs free energies of U in two phase coexisting states were calculated through the measurement of electromotive force. Galvanostatic electrolysis was then conducted to prepare Bi-U intermetallic compound in the LiCl-KCl-UCl 3 melt on a liquid Bi electrode. The phase composition and microstructure of the alloy was characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS).
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