High-sensitivity detection of H2S by In2O3/C composite prepared by inert-ambient sealed-tube pyrolysis

Raghavan, MS and Shivashankar, SA (2019) High-sensitivity detection of H2S by In2O3/C composite prepared by inert-ambient sealed-tube pyrolysis. In: SN Applied Sciences, 1 (7).

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Abstract

Indium acetylacetonate, a β-diketonate complex, was pyrolyzed at 700 °C in inert ambient in a sealed quartz tube, to yield a powder composite of nanocrystalline In2O3 and elemental carbon (In2O3/C), as deduced from characterization by powder X-ray diffraction and Raman spectroscopy. Scanning electron microscopy shows that the metal oxide is embedded in micrometer-sized spherical structures, composed largely of carbon. The spherical entities are likely formed when the metal complex melts, decomposes, and vaporizes during pyrolysis, with the vapour condensing into spherical �droplets� as the sealed tube cools gradually to room temperature. The In2O3/C composite was tested (in pellet form) as a gas sensor, specifically the conductometric sensing of H2S. At 5 ppm of H2S, the composite shows a high response of 225 at 250 °C, with the response and recovery being swift (~ 5 s and ~ 15 s, respectively). At 250 °C, the detection limit is found to be of 500 ppb of H2S, with selectivity over NH3, NO2, CH4, and SO2 being considerable. The In2O3/C sensor also displays good cyclability. When carbon in the composite is removed by annealing it in air (550 °C, 60 min), the resulting In2O3 powder (in pellet form) shows a much poorer response to H2S at 250 °C (25 to 5 ppm), illustrating that the elemental carbon in In2O3/C enhances sensitivity to H2S. The advantages of a simple fabrication process and low power consumption make the carbonaceous composite sensor potentially useful. © 2019, Springer Nature Switzerland AG.

Item Type:	Journal Article
Publication:	SN Applied Sciences
Publisher:	Springer Nature
Additional Information:	The copyright of this article belongs to Springer Nature
Department/Centre:	Division of Interdisciplinary Sciences > Centre for Nano Science and Engineering
Date Deposited:	05 Mar 2021 09:57
Last Modified:	05 Mar 2021 09:57
URI:	http://eprints.iisc.ac.in/id/eprint/68142

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