Electrodeposition of UO2 nanoparticles in molten salt with microplasma gaseous cathode

Abstract

Nano-sized UO2 particles have great application potential in the field of nuclear fuel fabrication and catalysis, while most of the current synthesis methods either cannot obtain products with high stability or need to introduce organic agents which would cause organic residue pollution. Herein, we have developed a new synthesis method by combining the microplasma gas electrode with molten salt electrochemistry. Uranyl ions (UO22+) in molten salt can be directly reduced to UO2 nanoparticles at the interface between plasma and molten salt. These particles have uniform size distribution, strong crystallization and high purity, with no organic reagent contamination or volatilization concerns, and show good long-term oxidation resistance in water, without any change for more than 30 days. The effects of electrolytic parameters such as electrolytic time, melt temperature, initial UO22+ concentration, and electrolytic current on the composition and size of the products have been studied. It is found that these electrolytic parameters have little effect on the composition of the products, which are all UO2, but strongly affect the size. The average particle size increased with electrolysis time, temperature, and the initial UO22+ concentration increased. According to these phenomena, the size of the product can be regulated at the range of 20–200 nm.