Electrochemical Investigation of Uranyl Nitrate in Ethaline DES and a New Approach for Direct Electrochemical Deposition of UO2

Abstract In the present study, systematic investigation of uranyl nitrate (UO2(NO3)2) dissolution in choline chloride-ethylene glycol (1.2 ratio; ethaline) deep eutectic solvent (DES) was done. Post dissolution, the electrochemical behavior of uranyl species was monitored using cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetric techniques on both Pt as well as on glassy carbon (GC) electrodes at different temperatures. Detailed CV and CA analyses confirmed diffusion controlled reduction of uranyl ion which was quasi-reversible in nature on Pt electrode but irreversible in nature on GC electrode. Based on the electrochemical investigations, the electron transfer mechanism, diffusion coefficient and kinetic rate constants were determined. For the first time, direct electrodeposition of UO2 from novel DES-based electrolyte UO2(NO3)2-ethaline was attempted and successfully deposited on copper electrode as confirmed by GIXRD of the deposited film. Deposited films surface morphology and chemical composition were further analyzed using field-emission scanning electron microscopy combined with energy-dispersive spectroscopy and X-ray photoelectron spectroscopy analysis respectively. The strategy adopted for the deposition of uranium oxide from DES can be implemented as novel recovery and obtaining thin films of uranium oxide.