Solvothermal synthesis of lanthanide-functionalized graphene oxide nanocomposites

We propose a facile approach to the preparation of graphene oxide (GO) composites with lanthanide (Ln) oxide/ hydroxide nanoparticles (Ln = La, Eu, Gd, Tb) under relatively mild conditions by two different procedures of solvothermal synthesis. The mechanism of GO-Ln nanocomposite formation is thought to involve the initial coordination of Ln3+ ions to the oxygen-containing groups of GO as nucleation sites, followed by f Ln2O3 and Ln (OH)3 nanoparticle growth. The nanocomposites obtained preserve the intrinsic planar honeycomb-like structures of graphene as proven by the typical G and D bands in the Raman spectra. Fourier-transform infrared and Xray photoelectron spectroscopy confirm the interaction between oxygen-containing groups of GO and Ln ions. The size and distribution of Ln oxide/hydroxide nanoparticles on GO sheets, estimated from scanning and transmission electron microscopy images, vary broadly for the different lanthanides. The size can span from subnm dimensions for Eu oxide to more than 10 mu m for Eu hydroxide nanoparticles. The most homogeneous distribution of Ln oxide/hydroxide nanoparticles was found in La-containing composites. Thermogravimetric analysis demonstrated that all the GO-Ln nanocomposites are thermally less stable, by up to 30 degrees C than pristine GO.

Automated summary

We propose a facile approach to prepare graphene oxide (GO) composites with lanthanide (Ln) oxide/hydroxide nanoparticles (Ln = La, Eu, Gd, Tb) under mild conditions. The mechanism of GO-Ln nanocomposite formation involves the coordination of Ln3+ ions to oxygen-containing groups of GO, followed by nanoparticle growth. The obtained nanocomposites show the honeycomb-like structure of graphene and the interaction between GO and Ln ions is confirmed. The size and distribution of Ln oxide/hydroxide nanoparticles on GO sheets vary for different lanthanides, with La-containing composites exhibiting the most homogeneous distribution. All GO-Ln nanocomposites are thermally less stable compared to pristine GO.