Enhanced ceria nanoflakes using graphene oxide as a sacrificial template for CO oxidation and dry reforming of methane

Abstract

The development of novel fabrication methods to produce ceria catalysts with good high-temperature stability is critical for their implementation across a range of different applications. Herein, graphene oxide flakes are used as a sacrificial template in the synthesis of ceria particles to replicate the graphene oxide's two-dimensionality. While performing the synthesis without graphene oxide results in large agglomerations of ceria crystallites, the addition of graphene oxide during the synthesis results in ceria nanoflakes (<10 nm) replicating the graphene oxide morphology. This novel shape limits the diffusion of atoms at high temperature to a two-dimensional plane which is translated into a low sintering degree and consequently, an enhanced thermal stability. In this way, the ceria flakes are capable of maintaining high surface areas after calcination at high temperatures (>400 °C) which results in improved catalytic performance for the oxidation of carbon monoxide. This resistance versus sintering has also a beneficial effect when ceria flakes are used as catalytic support of nickel particles. Improved metal dispersion and high metal-support interaction leads to lower sintering during the dry reforming of methane than similarly prepared un-templated ceria nickel catalysts. These results demonstrate the advantage of using graphene oxide as a sacrificial template for the production of sintering-resistant catalysts with good catalytic performance at high temperatures.