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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. [ABSTRACT FROM AUTHOR]

Single-walled carbon nanotubes (SWNTs) with a toroidal/coiled geometry-shaped structure sustain innovative preference to future technology material. The toroidal shape can be used in designing nanoelectronic devices for various prospective applications such as tactile sensors, electromagnetic absorbers, and energy storage devices. In this study, we demonstrate the fabrication of toroidal geometry shapes of metallic (m-) and semiconducting (s-) SWNTs, which can be revealed by simply mixing a few solutions in the correct ratio, both oil-in-water (hydrophobic) and water-in-oil (hydrophilic) emulsion processes. Herein, the letter communicates the formation of pure m- and s-SWNTs (metallic and semiconducting) by annular, obtained from gel column chromatography, via the emulsion approach. We have also studied the surfactant sodium dodecyl sulfate removal of sorted species from a gel column by a simple method named as chloroform/methanol/water extraction., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)