Stable Uranium Oxide Under Atmospheric Conditions: An Electroplating Technique for U Film Fabrication at Boron-Doped Diamond Electrodes

Abstract

An electrodeposition technique of low-enriched uranium onto boron-doped diamond (BDD) electrodes for uranium electro-assembling, sequestration, uranium electrowinning (as the electroextraction alternative), and future neutron detection applications has been developed. Our findings through physicochemical characterization and an in-depth XPS analysis show that the U/BDD system consists of a blend of uranium oxides with IV, V, and VI oxidation states. Results show that U5+ is present and stable under open atmospheric conditions. The U electrodeposition on BDD creates smooth surfaces, free of voids, with uniform deposition of homogeneous tiny particles of stable uranium oxides, instead of chunky particles, and uranium compound mixtures, like large fibers of the precursor uranyl. Our electrochemical method operates without high temperatures or hazardous compounds. Uranium corrosion and oxidation processes occur spontaneously and parallel to the electrochemical formation of metallic uranium on BDD electrode surfaces, with metallic uranium reacting with water, producing fine particles of UO2. This work represents the first attempt to create a surface of uranium oxides, where the film thickness can be controlled for future applications, e.g., improving sensitivity in neutron detection technologies. Our U electro-assembling method provides a sustainable strategy for uranium electro-recovery from nuclear wastes, immobilizing uranium as a storage method or as U-film fabrication (U/BDD) for future neutron detection applications. Besides, this work contributes to uranium-based technologies, improving them and providing a better understanding of their electrochemical properties, e.g., uranium redox processes, uranium oxides’ formation, and stability evaluation. These properties are of remarkable need for uranium-based target formation. The use of our U/BDD method is proposed as an environmental protocol to recover and immobilize uranium-235, and other fissile materials, from civil and defense wastes, contaminated systems, and stockpiles.

Uranium electrodeposition at boron-doped diamond electrodes

“…In-depth curve-tting analyses were performed for the C1s and O1s regions based on our prior study, while the valence band XPS binding energy region for the U/BDD electrode surface was explored within the 0 to 35 eV range [23]. This region encompasses the outer valence molecular orbitals (0 to 15 eV) and the inner valence molecular orbitals (15 to 35 eV).…”

“…In our recent work, a novel electrochemical methodology was developed to produce homogeneous U-thin layers on boron-doped diamond (BDD) electrodes [23]. Employing chronoamperometry as an electrodeposition technique and applying − 1.75V vs. RHE in aqueous media at room temperature, our method yielded homogeneous U-lms with a uranium-based coating predominantly composed of stable uranium oxides (UO 2 , U 3 O 8 , and UO 3 ), devoid of voids and traces of the acetate-based precursor.…”

“…Although our electroplating method exhibited superior uranium electroplating performance compared to previous reports utilizing cyclic voltammetry and chronoamperometry techniques in molten salts, [24][25][26][27][28] we sought to delve deeper by evaluating the in uence of different electrodeposition potentials on the nal con guration of the U-lms. The primary challenge encountered in uranium electrodeposition in aqueous media is the hydrogen evolution reaction (HER) [23]. Despite the underexplored nature of electrodeposition methodologies in the HER potential region, our previous works demonstrated the electrodeposition of various metals in a potential window associated with high current pro les related to the HER [29,30].…”

“…Despite the underexplored nature of electrodeposition methodologies in the HER potential region, our previous works demonstrated the electrodeposition of various metals in a potential window associated with high current pro les related to the HER [29,30]. Given these considerations, and to comprehensively explore the in uence of electrodeposition potential on the features of our U-lms, [23] we conducted an in-depth atomic force microscopy (AFM) study to assess their morphology, topography, and roughness.…”