Controllable decoration of CVD-grown graphene with Au NP as a promising ammonia sensing platform

Controllable electroless deposition is proposed for Au nanoparticles (Au NPs) decorated on chemical vapor deposition growth graphene sheet (GS). This method is very simple and easy to manipulate because the redox potential difference between Cu the GS grown substrate and Au helps Au ions in precursor solution reduced to Au NPs. The coverage and size of Au NPs on GS could be controlled in range of 0-61.4 % and 30-140 nm, respectively. Three samples S1, S2 and S3 of spheric Au NPs on GS with coverage 11.5, 21.2 and 22.2 % are transferred to SAW sensor as sensing element for ammonia gas detection. The sensitivities of S1, S2 and S3 are all an order in magnitude higher than that of S0 of pristine GS for ammonia gas detection. Both recovery times and response time of S1, S2 and S3 are shorter than that of S0. The results may provide new thoughts about improving graphene based gas sensor properties.