Effect of graphene sheets on the physico-chemical properties of nanocrystallite ceria.

Abstract

Currently, replacing expensive and short-lived materials for supercapacitors based on RuO₂ with more cost-effective and high-performance materials that remain operational after a large number of cycles is a challenge. Cerium-based materials are the most attractive alternative because of cerium's ability to quickly change oxidation state. This work proposes the synthesis of nanostructured graphene-ceria composite and studies its morphological features arising under the impact of oxygen-free graphene. The mechanism of formation of nano-ceria crystallites when the sol-gel transition occurs on the surface of graphene sheets is also considered. It has been proven that the introduction of 0.5-0.6 wt% graphene sheets into nano-ceria ensures the preservation of its single-phase state, while simultaneously increasing its dispersion. Using the dilatometry method, it has been determined that uniformly distributed sheets of oxygen-free graphene lead to a decrease in temperature of the beginning of composite sintering by 175°C compared with pure nano-ceria and increase the shrinkage value by two times, which, in turn, should promote better sintering. This study fills a gap in the synthesis and characterization of oxygen-free graphene composites, promising raw materials for small devices and large power plants.