Gas sensing performance of hydrothermally grown CeO2-ZnO composites (original) (raw)
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Nanocrystalline sensors having the general formula ZnO + x wt% CeO2, where x = 0, 2, 4 and 6 were prepared by chemical precipitation method and sintered at 400, 600 and 800 oC for 2h in static air atmosphere. The crystal structure and the morphology of the prepared samples were investigated and characterized by using XRD, IR, SEM and TEM techniques. The investigation revealed that the average crystallites size increases with increasing the sintering temperature. The electrical conductivity is found to increase with CeO2 additions and sintering temperature. Gas sensing properties of the prepared samples were also investigated. The effect of CeO2 content and sintering temperature on the structure, electrical conductivity and ethanol gas sensing properties of the prepared samples are discussed.
Modern Applied Science, 2015
Carbon monoxide (CO) is a poisonous gas and could be lethal towards human. A sensitive CO gas sensor isnecessary to prevent accidents caused by CO gas. ZnO is a semiconductor material having many applicationsincluding gas sensors. However ZnO is rarely reported to be used as CO gas sensor material. Therefore, in thisresearch, CO gas sensor has been prepared from ZnO material synthesized via hydrothermal process at 100°C for24 hours using ZnCl2 powder and NH4OH solution. The resulted ZnO gel was subsequently dried andspin-coated on a glass substrate. The ZnO-coated glasses were then calcined at various temperatures of 500°C,550°C, and 600°C for 30 minutes. Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD),Brunauer-Emmet-Teller (BET) analysis were used to characterized the morphology, structure and active surfacearea of ZnO. The sensitivity of the ZnO material towards CO gas was measured using a potentiostat in achamber with operating temperatures 30°C, 50°C, and 100°C with ...
CeO2 doped ZnO flower-like nanostructure sensor selective to ethanol in presence of CO and CH4
Sensors and Actuators B: Chemical, 2012
CeO 2 -doped ZnO nanostructures, with different Ce/Zn ratios, were synthesized via a very fast microwaveassisted method using zinc acetate dihydrate and cerium nitrate as starting materials and water as solvent. The samples were characterized via SEM, EDX, XRD, and BET analyses. Gas sensitivity of the fabricated sensor was studied for selective detection of ethanol in presence of CO and CH 4 and effect of CeO 2 with different concentrations as a dopant was investigated. 5 wt% CeO 2 doped sample was shown to improve the sensor response to 500 ppm ethanol with high selectivity in presence of CO and CH 4 . Furthermore presence of ceria reduced the recovery time of the sensor significantly. The CeO 2 -doped ZnO may be considered a promising sensing material for selective detection of ethanol.
Undoped and Cobalt Doped ZnO Thin Films Ethanol Gas Sensors
In this research, undoped ZnO and doped with cobalt ZnO:Co thin films with different weight percentages of (1, 3, 5,7 )% have been prepared on pre-heated glass substrates up to (400℃) with average thickens (300nm) by using Atmospheric Pressure Chemical Vapor Deposition (APCVD) technique. The effect of Co-doping on structural properties and the ethanol vapor gas sensing has been investigated. The results of XRD showed that the all deposited films are polycrystalline hexagonal structure with a preferred orientation in the (002) direction, the doping with Co does not change crystal structure of ZnO. The increase in the dopant concentration into the ZnO leads to an increase of the crystallite size of the films which is well known causes to increase the gas sensitivity. The effect of operating temperature on performance of the sensor material has been investigated and a choice of optimum temperature was made at around 300 °C.
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A B S T R A C T Nanostructured ZnO thin films have been deposited using a successive chemical solution deposition method. The structural, morphological, electrical and sensing properties of the films were studied for different concentrations of Al-dopant and were analyzed as a function of rapid photothermal processing temperatures. The films were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron and micro-Raman spectroscopy. Electrical and gas sensitivity measurements were conducted as well. The average grain size is 240 and 224 Å for undoped ZnO and Al-doped ZnO films, respectively. We demonstrate that rapid photothermal processing is an efficient method for improving the quality of nanostructured ZnO films. Nanostructured ZnO films doped with Al showed a higher sensitivity to carbon dioxide than undoped ZnO films. The correlations between material compositions, microstructures of the films and the properties of the gas sensors are discussed. ß
Fabrication and Characterization of ZnO Gas Sensor
Eng. & Tech. Journal, 2014
In this paper thin films of zinc oxide ZnO was prepared by spray pyrolyess method with thickness were about (0.1 ±0.05 µm) on n-type silicon substrates at different deposition temperature (300,400,500) C°, from zinc chloride at concentrations (0.05,0.1) M as a sensor for pollutant gases like CO 2 , NO 2 , and H 2 S related with oil manufacture. The crystallinity and morphology of the films were characterized by XRD, and optical microscopy was done on prepared films , addition to sensitivity to polluting gases previously mentioned at different test temperature (10-50) C°. Result shows that the crystallization increased by increasing deposition temperature(substrate temperature), and the sensitivity increased by rising both of the gas concentration or temperature.
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Acta Physica Polonica A
Zinc oxide (ZnO) nanostructures were deposited on glass substrates by physical vapor deposition technique. To improve the crystallinity of ZnO, oxidation treatment was conducted at 400 • for 1 h in an atmospheric environment. The films characteristics of the films were examined by X-ray diffraction, ultraviolet-visible spectroscopy, atomic force microscopy, and scanning electron microscopy. The X-ray diffraction results illustrated that the deposited films have a polycrystalline hexagonal structure. The ultraviolet-visible spectrum showed that the transmittance of the ZnO film has an energy gap of about 3.225 eV. The atomic force microscopy images indicated that the films have good homogeneity, and the scanning electron microscopy images reveal that they consist of spherical nanosized grains with a granular surface. The ZnO films revealed good sensing performance to acetone and ethanol gases at an operating temperature of 25 • C with suitable recovery and response times. The sensitivity measured by homemade gas sensor system was approximately 21.
Sensors and Actuators B-chemical, 2006
Highly crystalline zinc oxide (ZnO) nanoparticles have been synthesized by hydrothermal route at 120 • C over a range of different time periods. The synthesized nanoparticles are characterized for their phase and morphology by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermogravimetric-differential thermal analysis (TG-DTA) follows the thermal changes accompanying the heat treatment and ultra-violet diffuse reflectance spectroscopic studies (UV-DRS) give a measure of the optical properties. Electrical properties of the synthesized nanoparticles are studied by AC impedance and DC conductivity measurement. The gas sensing properties were studied towards reducing gases like liquefied petroleum gas (LPG), ammonia, hydrogen, ethanol (EtOH), etc., and it is observed that the nanoparticles show high sensitivity to LPG and ethanol at relatively low operating temperatures. Pd incorporation results in a decrease in operating temperature by more than 100 • C, and improves the sensing characteristics in terms of response and recovery times.
Journal of Physics: Conference Series, 2020
Fabrication of zinc oxide (ZnO) nanorods thin films based gas sensing ethanol have been done. Ethanol belongs to volatile organic compound (VOC) that are dangerous if inhaled by humans in high concentrations, so that its detection is necessary. Temperature as kinetic controller of chemical bath deposition (CBD) process take effect to ZnO fabrication and characterization. ZnO nanorods thin films was synthesized onto glass substrate by dip-coating technique. ZnO nanorods was grown using Zn(NO3)2.4H2O and HMTA with ratio 1:1 under CBD condition at temperature 75 o C, 83 o C, and 87 o C. Result of SEM showing ZnO CBD 83 o C has nanorods shape with diameter size is 95.56 nm, furthermore at 75 o C the formation of the nanorods was not completed yet while at nanorods became deconstructed. XRD result showed all of ZnO sample have hexagonal wurzite which are match well with ICDS-094004 card. Ethanol gas sensing tested at 100 o C, 150 o C, 200 o C showed high sensitivity of the sensor up to 77.31% for ZnO CBD 75 o C at 100 o C. ZnO CDB 83 o C sample at test 200 o C have highest response on 2.22 min (tres) and 0.45 min (trec). Time respond and recovery will increase along with increasing of test temperature.