Rapid and efficient preparation of uranium layers by electrodeposition from aqueous and organic solution systems

Targets containing high-density uranium layers are the primary material to produce ⁹⁹Mo for medical use. Herein, the optimal parameters for the preparation of uranium deposited layers by different methods were obtained by comparing the direct current (DC) and pulsed electrodeposition of uranium in aqueous and organic solutions. The four techniques for preparing uranium layers in this study were ranked in order of their advantages as follows: DC electrodeposition, pulsed electrodeposition, DC molecular plating (DCMP), and pulsed molecular plating (pulsed MP). Uranium layers up to 3.04 mg/cm² were prepared by DC electrodeposition in aqueous solution and up to 6.87 mg/cm² by DCMP in DMF. Simulations using Visual MINTEQ software determined that UO₂(CO₃)₃^4- is the dominant species of uranium in carbonates at pH > 8 with over 94 %. Cyclic voltammetry was used to establish the one-electron transfer process of UO₂(CO₃)₃^4-, and it was determined that the reduction process of UO₂(CO₃)₃^4- was controlled by diffusion. SEM and EDS results proved that the uranium layer obtained in aqueous solution was uniformly distributed on the surface of the 304 stainless steel (304SS) electrode, which conformed to the layer-by-layer (Frank-van der Merwe) growth mode, while the uranium layer obtained in DMF was not uniformly distributed on the surface of the 304SS, which conformed to the island-like (Volmer-Weber) growth mode. XPS, FTIR and XRD results proved that uranium was mainly deposited on the surface of 304SS as UO₂ and U₃O₈ in aqueous solution, and as UO₃ and UO₂(OH)₂ in DMF.