Sol–gel chemistry for graphene–silica nanocomposite films

Fabrication of graphene nanocomposite films via sol–gel chemistry is still a challenging task because of
the low solubility of graphene in common solvents. In the present work we have successfully developed
a suitable synthesis method employing a solution of exfoliated graphene in 1-vinyl-2-pyrrolidone that
is added to an anhydrous sol of silicon tetrachloride in ethanol. Thin graphene–silica films with high
optical transparency have been obtained; the graphene sheets are composed of two layers and do not
aggregate at a large range of concentrations upon incorporation into the matrix. Thermal processing of
the silica films allows complete removal of 1-vinyl-2-pyrrolidone without oxidation or degradation of the
graphene sheets which are embedded in the oxide.