Green mechanochemical fabrication of graphite-lanthanide oxide nanocomposites

Abstract

In this study, we explored mechanochemistry as a facile and environmentally friendly approach for the synthesis of graphite-lanthanide oxide nanocomposites. We determined the optimal conditions, namely a milling time of 48 h and milling ball size of 10 mm diameter, for which processing mixtures of graphite and lanthanide oxide in a planetary ball mill resulted in exfoliated graphene nanosheets functionalised with lanthanide oxide particles. The prepared nanocomposites were investigated by a suite of analytical techniques; X-ray photoelectron spectroscopy proved that mechanochemical processing in the presence of lanthanide oxides functionalises the graphene surface. Raman spectroscopy and X-ray diffraction results evidenced that the mechanochemical treatment exfoliates graphite and reduces the size of graphite crystallites. Scanning electron microscopy and scanning transmission electron microscopy confirmed the formation of lanthanide oxide nanoparticles and their uniform distribution on the graphene surface and thermogravimetric analysis gave evidence that the graphite-lanthanide oxide nanocomposites are less thermally stable than pristine graphite. The toxicity of the graphite-lanthanide oxide nanocomposites was also studied; we found that COS-7 monkey kidney cell growth was not inhibited for more than 5% in most of the studies.