Synthesis and preservation of graphene-supported uranium dioxide nanocrystals

Graphene-supported uranium dioxide (UO₂) nanocrystals are potentially important fuel materials. Here, we investigate the possibility of synthesizing graphene-supported UO₂ nanocrystals in polar ethylene glycol compounds by the polyol reduction of uranyl acetylacetone under boiling reflux, thereby enabling the use of an inexpensive graphene precursor graphene oxide into a one-pot process. We show that triethylene glycol is the most suitable solvent with an appropriate reduction potential for producing nanometer-sized UO₂ crystals compared to monoethylene glycol, diethylene glycol, and polyethylene glycol. Graphene-supported UO₂ nanocrystals synthesized with triethylene glycol show evidence of heteroepitaxy, which can be beneficial for facilitating heat transfer in nuclear fuel particles. Furthermore, we show that graphene-supported UO₂ nanocrystals synthesized by polyol reduction can be readily stored in alcohols, impeding oxidation from the prevalent oxygen in air. Together, these methods provide a facile approach for preparing and storing graphene-supported UO₂ nanocrystals for further investigation and development under ambient conditions.