A new hydrogen cyanide chemiresistor gas sensor based on graphene quantum dots

Abstract

Graphene quantum dots (GQDs), synthesised via controlled carbonisation of citric acid, were reduced by hydrazine hydrate and then used as hydrogen cyanide (HCN) gas sensors. Checking of the reduction step by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) techniques revealed that most of the oxygen-containing functional groups were removed from the GQDs. It was observed the reduction process is necessary for sensitising of GQDs for HCN gas. The electrical resistance of the reduced GQDs was increased as a result of their exposure to HCN gas. Accepting a p-type semiconducting characteristic for GQD material, the above-mentioned behaviour suggested electron donation from HCN to GQD. The sensor response to HCN gas was reversible, suggesting a reversible adsorption/desorption phenomenon of HCN to the GQDs. The response as well as the recovery time of the sensor was different depending on the HCN concentration tested. The developed sensor showed linear HCN response from 1 to 100 ppm. The detection limit of the sensor was estimated to be 0.6 ppm (S/N).Relative standard deviation f HCN determination by the developed sensor was calculated to be 5.7% (n = 4, [HCN] = 50 ppm). The sensor response was did not vary significantly within 6 months. ARTICLE HISTORY

Fabrication of ultra-small monolayer graphene quantum dots by pyrolysis of trisodium citrate for fluorescent cell imaging

“…It should be noted that the GQDs exhibit nearly no absorption of C-H and C-O-C, implying that they have few surface defects and main functional group of carboxyl on the edge. 28,38 These oxygen-containing functional groups make GQDs soluble in aqueous medium. Even stored for 3 months, there is no precipitation.…”

Enhancement of Dye‐sensitized Solar Cells Efficiency Using Graphene Quantum Dots as Photoanode

“…The Figure 5(b) presents blue luminescence of various sizes of GQDs. 33 Optical properties of graphene determined by photoluminescence indicate that the monolayer of graphene had higher amplification of PL than that of multiple layers. It is probably due to the electron phonon scattering from high-power light source.…”

“…It is probably due to the electron phonon scattering from high‐power light source . In addition the light scattering can be caused by excited state relaxation and by adding a dopant electrically . Optical properties of graphene determined by photoluminescence indicate that the monolayer of graphene had higher amplification of PL than that of multiple layers.…”

Resistive-Based Gas Sensors Using Quantum Dots: A Review

“…GQDs also exhibit new features because of the quantum confinement and boundary effects [85]. Thanks to the conjugated π structure, dangling bonds, defects, high surface area, and outstanding electronic mobility, GQDs are promising materials for gas and humidity sensing studies [86][87][88][89][90][91]. Different techniques for synthesis of GQDs have been described in [92,93].…”