Electrochemical behaviour of uranium (IV) in DMF at vitreous carbon |
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Authors: | ML Afonso A Gomes A Carvalho LC Alves F Wastin AP Gonalves |
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Affiliation: | aInstituto Tecnológico e Nuclear/CFMC-UL, P-2686-953 Sacavém, Portugal;bCCMM, Departamento de Química e Bioquímica da Faculdade de Ciências, Universidade de Lisboa, Campo Grande Ed. C8, 4°Piso, P-1749-016 Lisboa, Portugal;cInstituto Tecnológico e Nuclear/CFN-UL, P-2686-953 Sacavém, Portugal;dEuropean Commission, JRC, Inst. Transuranium Elements, D-76125 Karlsruhe, Germany |
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Abstract: | The electrochemical behaviour of UCl4 (0.01 mol L−1 up to 0.05 mol L−1) in 0.1 mol L−1 TBAPF6/DMF solution at vitreous carbon was studied, at room temperature, by cyclic voltammetry and potentiostatic techniques. The electrolytic solutions were analyzed by UV spectroscopy (UV), and the electrodeposited films were characterized by Rutherford Backscattering Spectroscopy (RBS) and X-ray diffraction (XRD). The cyclic voltammetric results, at low UCl4 concentrations (0.01 mol L−1), point that the reduction of U(IV) to U(0) occurs in two steps involving mainly U(IV) and U(III) species. The first electron transfer reaction is quasi-reversible and the second irreversible. The diffusion coefficient of U(IV) in DMF and the charge rate constant were determined to be 4.78 × 10−7 cm2 s−1 and 1.93 × 10−3 cm s−1 (at 0.02 V s−1), respectively.RBS data obtained from samples prepared at constant potential (−3.10 V) during 3 h at room temperature, indicated the presence of uranium particles deposited all over the vitreous carbon surface with aggregates in some places, confirming that the second reduction step corresponds to uranium electrodeposition. No crystallographic ordering could be seen by XRD, pointing to an amorphous character of the uranium films. |
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Keywords: | Uranium tetrachloride Dimethylformamide Cyclic voltammetry Vitreous carbon electrode Electrodeposition |
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