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Sensing of oxidizing and reducing gases by sensors prepared using nanoscale Co3O4 powders: A study through Cu substitution

Giri, S and Anantharamaiah, PN and Sahoo, B (2022) Sensing of oxidizing and reducing gases by sensors prepared using nanoscale Co3O4 powders: A study through Cu substitution. In: Advanced Powder Technology, 33 (4).

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We demonstrate the sensing-mechanism of both oxidising and reducing gases by nanoscale Co3O4 powders through a strategy of Cu-doping in Co3O4. The sensitivity towards both types of gases arises due to presence of Co2+ and Co3+ cations in the (nearly) normal spinel structure of Co3O4. Pellets made up of nanopowders were employed for the detection of �6.5 ppm CO gas present in either pure N2 or in a mixture of synthetic air as carrier gas (which represents the O2 sensing-gas too). The high sensitivity of Co3O4 nanoparticles to detect �6 ppm CO (in N2) arises due to the high surface area of nanopowders exposing a higher number of octahedral Co3+ cations as adsorption sites, whereas the sensitivity towards O2 arises due to partial presence (less number) of octahedral Co2+. To support this mechanism, octahedrally Cu2+ substituted Co3O4 specimens are investigated. The inactive Cu2+ at the octahedral site changes the unexposed tetrahedral Co2+ into Co3+. The presence of inactive Cu2+ at the octahedral site and the burial of the Co3+ at the tetrahedral sites reduce the adsorption sites for O2, thereby drastically reducing the overall O2-gas sensitivity shown by the Cu-substituted sample, although they have higher surface-area (nanoparticles). © 2022 The Society of Powder Technology Japan

Item Type: Journal Article
Publication: Advanced Powder Technology
Publisher: Elsevier B.V.
Additional Information: The copyright for this article belongs to Elsevier B.V.
Keywords: Chemical detection; Copper; Gas detectors; Gases; Nanoparticles; Nanostructured materials; Positive ions; Powders, Adsorption site; Carbon monoxide; Cu substitutions; Gas sensing mechanism; Gas-sensors; High surface area; Nano powders; Nano scale; Oxidizing gas; Reducing gas, Carbon monoxide
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 15 May 2022 08:19
Last Modified: 15 May 2022 08:19
URI: https://eprints.iisc.ac.in/id/eprint/71682

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