Graphene-mediated surface enhanced Raman scattering in silica mesoporous nanocomposite films

Silica mesoporous nanocomposite films containing graphene nanosheets and gold nanoparticles have
been prepared via a one-pot synthesis using silicon tetrachloride, gold(III) chloride tetrahydrate, a
1-N-vinyl-2-pyrrolidone dispersion of exfoliated graphene and Pluronic F127 as a structuring agent. The
composite films have shown graphene-mediated surface-enhanced Raman scattering (G-SERS).
Graphene has been introduced as dispersed bilayer sheets while gold has been thermally reduced in situ
to form nanoparticles of around 6 nm which preferentially nucleate on the surface of the graphene
nanosheets. The presence of graphene and gold nanoparticles does not interfere with the self-assembly
process and silica mesoporous films ordered as 2D hexagonal structures. The material has shown a
remarkable analytical enhancement factor ranging from 80 up to 136 using rhodamine 6G as a Raman
probe. The films have been characterised by grazing incidence X-ray diffraction, FTIR and UV-vis
spectroscopy studies; transmission electron microscopy and spectroscopic ellipsometry have been used
to study the morphology, thickness and porosities of the samples. Raman spectroscopy has been
employed to characterise the graphene nanosheets embedded into the mesoporous films and enhanced
Raman scattering.