  We investigated the vapour sensing properties of different graphene-gold
hybrid nanostructures. We observed the shifts in the optical spectra near the
local surface plasmon resonance of the gold nanoparticles by changing the
concentration and nature of the analytes (ethanol, 2-propanol, and toluene).
The smaller, dome-like gold nanoparticles proved to be more sensitive to these
vapours compared to slightly larger, flat nanoparticles. We investigated how
the optical response of the gold nanoparticles can be tuned with a corrugated
graphene overlayer. We showed that the presence of graphene increased the
sensitivity to ethanol and 2-propanol, while it decreased it towards toluene
exposure (at concentrations higher than 30%). The slope changes observed on the
optical response curves were discussed in the framework of capillary
condensation. These results can have potential impact on the development of new
sensors based on graphene-gold hybrids.
