One-step in situ synthesis of CeO2 nanoparticles grown on reduced graphene oxide as an excellent fluorescent and photocatalyst material under sunlight irradiation

Abstract

CeO₂ nanoparticles (NPs) with average particle size of ∼17 nm were grown on graphene sheets by simply mixing cerium chloride as the Ce precursor with graphene oxide (GO) in distilled water and the simultaneous reduction of GO to reduced graphene oxide (rGO), followed by a one-step hydrothermal treatment at 150 °C. A unique blue to green tuneable luminescence was observed as a function of the excitation wavelength. With this method, significant applications of rGO–CeO₂ nanocomposites in many optical devices could be realized. The photocatalytic activity of the as-synthesized CeO₂ and rGO–CeO₂ nanocomposite was investigated by monitoring the degradation of methylene blue (MB) dye under direct sunlight irradiation. The rGO–CeO₂ nanocomposite exhibited excellent photocatalytic activity compared to CeO₂ NPs by degrading 90% of the MB dye in 10 min irradiation under sunlight. This property of rGO–CeO₂ nanocomposites was ascribed to the significant suppression of the recombination rate of photo-generated electron–hole pairs due to charge transfer between rGO sheets and CeO₂ NPs and the smaller optical band-gap in the rGO–CeO₂ nanocomposite.