Graphene-enhanced Raman imaging of TiO ₂ nanoparticles

The interaction of anatase titanium dioxide (TiO ₂) nanoparticles with chemical vapour deposited graphene sheets transferred on glass substrates is investigated by using atomic force microscopy, Raman spectroscopy and imaging. Significant electronic interactions between the nanoparticles of TiO ₂ and graphene were found. The changes in the graphene Raman peak positions and intensity ratios indicate that charge transfer between graphene and TiO ₂ nanoparticles occurred, increasing the Raman signal of the TiO ₂ nanoparticles up to five times. The normalized Raman intensity of TiO ₂ nanoparticles per their volume increased with the disorder of the graphene structure. The complementary reason for the observed enhancement is that due to the higher density of states in the defect sites of graphene, a higher electron transfer occurs from the graphene to the anatase TiO ₂ nanoparticles.