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Room-temperature methane gas sensing properties based on in situ reduced graphene oxide incorporated with tin dioxide
- Lam, King Cheong, Huang, Bolong, Shi, San-Qiang
- Journal of materials chemistry A 2017 v.5 no.22 pp. 11131-11142
- ambient temperature, ascorbic acid, dehydroascorbic acid, density functional theory, electrical conductivity, glucose, graphene oxide, hydrazine, methane, moieties, oxygen, reducing agents, sodium borohydride, synergism, tin dioxide
- We report on the relationship between the degree of reduction of graphene oxide (GO) and its room-temperature methane gas-sensing response by comparing four in situ reducing agents of GO: d-glucose, sodium borohydride, l-ascorbic acid and hydrazine hydrate. We found that gas sensing based on d-glucose and l-ascorbic acid had a higher gas response than that based on sodium borohydride and hydrazine hydrate because the residues contained oxygen functional groups. The poorly conductive GO was successfully reduced in situ by l-ascorbic acid to achieve high electrical conductivity and a high methane gas response. The incorporation of tin dioxide (SnO₂) into the reduced GO (RGO) further increased the gas response by the p–n junction effect. The heterostructure of l-ascorbic acid-reduced RGO–SnO₂ had the highest increase in methane response due to the synergistic effect between dehydroascorbic acid and the SnO₂ surface. This was inferred from density functional theory calculations with self-consistently determined Hubbard U potentials (DFT+U). Compared with the current room-temperature methane sensing and fabrication technologies, the sensing technology reported here is cheaper to produce and more environmentally friendly while retaining the best sensitivity and wider sensing range.