Porous-layered stack of functionalized AuNP–rGO (gold nanoparticles–reduced graphene oxide) nanosheets as a sensing material for the micro-gravimetric detection of chemical vapor

With oleylamine as a solvent and reducing agent, Au nanoparticles (AuNPs) are grown in situ on graphene oxide (GO) sheets. Thereafter, a porous-layered stack of AuNPs–GO nanosheets is formed by a gas-phase chemical reduction step. After the AuNPs are modified with 11-mercaptoundecanoic acid (11-MUA) to graft –COOH sensing groups to the amine, the functionalized AuNPs–rGO porous-layer stacked nanosheets are loaded onto a gravimetric resonant microcantilever for use as a mass sensing material. The rGO sheets serve as multi-layer nano-shelves to support and carry the functionalized AuNPs for gas adsorbing/sensing, while the AuNPs serve as nano-spacers between the rGO sheets to provide a high specific surface area for gas molecules accessing the material. The cantilever sensor experimentally exhibits a very rapid response to ppm-level trimethylamine (TMA) vapor, which is attributed to the novel sensing material. Compared with the hydrophilic AuNP–GO, the highly hydrophobic AuNP–rGO shows a much improved suppression to the noise from changes in environmental humidity. Featuring a rapid response, high sensitivity and good resistance to interference from environmental moisture, the novel sensing nanomaterial is promising in various chemical vapor detection applications.