Fabrication and Characterization of ZnO nanorods for room temperature Carbon Monoxide sensing application
28 Nov 2020-
TL;DR: In this paper, a Zinc Oxide (ZnO) nanorod based gas sensor for sensing CO gas is fabricated using a hydrothermal method over a rigid substrate.
Abstract: Detection of toxic gas mainly Carbon monoxide (CO) is very important to avoid loss of lives in various applications. Zinc Oxide (ZnO) nanorods based gas sensor for sensing CO gas is fabricated using a hydrothermal method over a rigid substrate. PEDOT: PSS is used to establish p-type over n-type ZnO nanorods. The material characterization of the fabricated sample is done using X-Ray Diffraction (XRD) revealing dominant, UV-Visible spectroscopy (UV-Vis), Photoluminescence spectroscopy (PL) and Field Emission Scanning Electron Microscope (FESEM). After the characterization of the material, the fabricated ZnO nanorod based sensor is exposed to CO gas at ppm ranging from 50 to 375 at room temperature using gas sensing setup. The sensitivity of the fabricated device is calculated and found to be 24.04%.
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TL;DR: The theory of operation is described and the response of the instrument to be described for different operating conditions is described, including the results obtained in fresh and aged forest-fire and urban plumes.
Abstract: Proton-transfer-reaction mass spectrometry (PTR-MS) allows real-time measurements of volatile organic compounds (VOCs) in air with a high sensitivity and a fast time response. The use of PTR-MS in atmospheric research has expanded rapidly in recent years, and much has been learned about the instrument response and specificity of the technique in the analysis of air from different regions of the atmosphere. This paper aims to review the progress that has been made. The theory of operation is described and allows the response of the instrument to be described for different operating conditions. More accurate determinations of the instrument response involve calibrations using standard mixtures, and some results are shown. Much has been learned about the specificity of PTR-MS from inter-comparison studies as well the coupling of PTR-MS with a gas chromatographic interface. The literature on this issue is reviewed and summarized for many VOCs of atmospheric interest. Some highlights of airborne measurements by PTR-MS are presented, including the results obtained in fresh and aged forest-fire and urban plumes. Finally, the recent work that is focused on improving the technique is discussed.
987 citations
TL;DR: In this paper, the electron conduction mechanism in the above-threshold regime in amorphous oxide semiconductor thin film transistors is shown to be controlled by percolation and trap-limited conduction.
Abstract: The electron conduction mechanism in the above-threshold regime in amorphous oxide semiconductor thin film transistors is shown to be controlled by percolation and trap-limited conduction. The band tail state slope controls the field effect mobility, while the average spatial coherence length and potential fluctuation control percolation conduction. In these limits, the field effect mobility is found to follow a power law, from which a universal mobility versus carrier concentration dependence is extracted.
251 citations
TL;DR: In this paper, Nanocrystalline ZnO films were deposited onto glass substrates by spray pyrolysis of zinc nitrate solutions and used as a liquid petroleum gas (LPG) sensor.
Abstract: Nanocrystalline ZnO films were deposited onto glass substrates by spray pyrolysis of zinc nitrate solutions and used as a liquid petroleum gas (LPG) sensor. The dependence of the LPG sensing properties on the molar concentration of zinc nitrate solutions was investigated. The ZnO films were oriented along (0 0 2) with the hexagonal crystal structure. The grain size and grain density increased with an increase in molar concentration of zinc nitrate solutions. The gas sensing properties for LPG of the ZnO films for LPG with different grain sizes were measured at different temperatures. The maximum sensitivity of 43% at the operation temperature of 673 K was found for the ZnO film prepared by spraying a 0.1 M solution. The ZnO thin films exhibited good sensitivity and rapid response–recovery characteristics to LPG. Further, it has been shown the gas sensitivity of the ZnO gas sensor depends upon its grain size.
219 citations
TL;DR: In this paper, the synthesis of Ag-doped ordered mesoporous tin(IV) oxide-titanium oxide nanohybrids using a sequential combination of a wet impregnation and nanocasting process is presented.
Abstract: Hybrid mesoporous metal oxides show promising attributes in the field of relative gas sensors due to the combined opportunities provided by the high specific surface area and framework components. In this study, we present the synthesis of Ag-doped ordered mesoporous tin(IV) oxide–titanium(IV) oxide nanohybrids using a sequential combination of a wet impregnation and nanocasting process and demonstrate the response by exposing the mesoporous nanohybrids to ethanol gas. HRTEM and N2 adsorption–desorption results indicate that the nanohybrids prepared by nanocasting of SBA-15 as the hard template possess an ordered mesoporous structure and high surface area. It was also observed that the mesoporous Ag-(TiO2/SnO2) shows excellent response towards ethanol with concentrations ranging from 1 ppm to 500 ppm. Besides, the nanohybrid mesoporous sensor shows high selectivity towards other volatile organic compounds (VOCs) including acetone, methanol, isopropanol, benzyl alcohol and ethyl acetate. All the results indicated that the nanocast mesoporous Ag-(TiO2/SnO2) nanohybrids have great potential for applications in designing high performance practical ethanol sensors.
207 citations
TL;DR: In this article, the authors investigated room temperature sensing characteristics of CuO films to various gases, i.e. Cl 2, H 2 S, NH 3, CH 4, CO and NO.
Abstract: We have investigated room temperature sensing characteristics of CuO films to various gases i.e. Cl 2 , H 2 S, NH 3 , CH 4 , CO and NO. CuO films were prepared by oxidation of Cu films, which were deposited on polycrystalline alumina substrates by thermal evaporation technique. CuO films have been found to be highly selective towards H 2 S. We demonstrate that the H 2 S response of CuO films can be divided in to three regions: (a) low concentrations (100–400 ppb), (b) intermediate concentrations (500 ppb to 50 ppm), and (c) high concentrations (>50 ppm). For low concentrations (100–400 ppb), the response curves have been found to be highly reversible with very small response (∼60 s) and recovery (∼90 s) times, indicating suitability of CuO films for sub-ppm sensing of H 2 S. Oxidation of H 2 S by adsorbed oxygen is found to be the responsible sensing mechanism. However, at very high H 2 S concentrations (>50 ppm), surface of CuO grains is found to convert into CuS, resulting in an irreversible response curve. For intermediate concentrations (500 ppb to 50 ppm), the response curve is governed by both H 2 S oxidation and CuS formation mechanisms.
190 citations