Anchoring noble metal nanoparticles on CeO2 modified reduced graphene oxide nanosheets and their enhanced catalytic properties.

The strategy of structurally integrating noble metal, metal oxide, and graphene is expected to offer prodigious opportunities toward emerging functions of graphene-based nanocomposites. In this study, we develop a facile two-step approach to disperse noble metal (Pt and Au) nanoparticles on the surface of CeO2 functionalized reduced graphene oxide (RGO) nanosheets. It is shown that Pt and Au with particle sizes of about 5 and 2nm are well dispersed on the surface of RGO/CeO2. The reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by NaBH4 was used as a model reaction to quantitatively evaluate the catalytic properties of the as-synthesized RGO/Pt/CeO2 and RGO/Au/CeO2 ternary nanocomposites. In such triple-component catalysts, CeO2 nanocrystals provide unique and critical roles for optimizing the catalytic performance of noble metallic Pt and Au, allowing them to express enhanced catalytic activities in comparison with RGO/Pt and RGO/Au catalysts. In addition, a possible mechanism for the enhanced catalytic activities of the RGO/Pt/CeO2 and RGO/Au/CeO2 ternary catalysts in the reduction of 4-NP is proposed. It is expected that our prepared graphene-based triple-component composites, which inherit peculiar properties of graphene, metal oxide, and noble metal, are attractive candidates for catalysis and other applications.