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Herein we demonstrate tungsten oxide (WO3 nanostructures based resistive type sensors for hydrogen sulfide (H2S) gas sensing utility. The WO3 dynamic layers have been deposited upon alumina substrates pre-patterned with gold (Au) interdigitated electrodes. For comparative study, two distinct WO3 nanostructures (S-425 and S-450) have been synthesized using Aerosol Assisted Chemical Vapor Deposition (AACVD) technique at varied deposition temperatures i.e., 425 and 450 °C, respectively. The gas detecting properties of both sensors were investigated against varied concentration (0-60 ppm) of H2S gas levels. The electrical resistance of fabricated gas detectors has been observed at DC bias of 5 V and low operating temperature 250 °C. Specifically, when concentration of H2S gas increases from 0-10 ppm, average resistance of the S-425 and S-450 gas sensors was observed to decrease by 96.5% and 97.6%, respectively. In general, the sensing mechanism of gas sensors proposed in this work can be associated with ionosorption of oxygen species over WO3 nanostructured surfaces. However, the significantly enhanced sensing performance of S-450 sensor may be attributed to improved crystallinity in its structure and improved ions adsorption/desorption kinetics at nanorods surface morphology.
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Shujah et al. (2019) studied this question.