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Ethanol-Sensing Characteristics of Nanostructured ZnO: Nanorods, Nanowires, and Porous Nanoparticles
Hanoi Univ Sci & Technol, Int Training Inst Mat Sci ITIMS, 1 Dai Co Viet, Hanoi, Vietnam.
Hanoi Univ Sci & Technol, Int Training Inst Mat Sci ITIMS, 1 Dai Co Viet, Hanoi, Vietnam.
Hanoi Univ Sci & Technol, Int Training Inst Mat Sci ITIMS, 1 Dai Co Viet, Hanoi, Vietnam.
Hanoi Univ Sci & Technol, Int Training Inst Mat Sci ITIMS, 1 Dai Co Viet, Hanoi, Vietnam.
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2017 (English)In: Journal of Electronic Materials, ISSN 0361-5235, E-ISSN 1543-186X, Vol. 46, no 6, 3406-3411 p.Article in journal (Refereed) Published
Abstract [en]

The morphology and crystalline size of metal oxide-sensing materials arebelieved to have a strong influence on the performance of gas sensors. In thispaper, we report a comparative study on the ethanol-sensing characteristics ofZnO nanorods, nanowires, and porous nanoparticles. The porous ZnOnanoparticles were prepared using a simple thermal decomposition of a sheet-like hydrozincite, whereas the nanorods and nanowires were grown byhydrothermal and chemical vapor deposition methods, respectively. Themorphology and crystal structure of the synthesized materials were charac-terized by field-emission scanning electron microscopy and x-ray diffraction.Ethanol gas-sensing characteristics were systematically studied at differenttemperatures. Our findings show that for ethanol gas-sensing applications,ZnO porous nanoparticles exhibited the best sensitivity, followed by thenanowires and nanorods. Gas-sensing properties were also examined withrespect to the role of crystal growth orientation, crystal size, and porosity.

Place, publisher, year, edition, pages
2017. Vol. 46, no 6, 3406-3411 p.
Keyword [en]
ZnO, porous nanoparticles, nanorods, nanowires, gas sensors
National Category
Other Materials Engineering
Identifiers
URN: urn:nbn:se:uu:diva-320148DOI: 10.1007/s11664-016-5270-2ISI: 000400560400019OAI: oai:DiVA.org:uu-320148DiVA: diva2:1088827
Available from: 2017-04-16 Created: 2017-04-16 Last updated: 2017-06-14Bibliographically approved
In thesis
1. Microfabricated Gas Sensors Based on Hydrothermally Grown 1-D ZnO Nanostructures
Open this publication in new window or tab >>Microfabricated Gas Sensors Based on Hydrothermally Grown 1-D ZnO Nanostructures
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, gas sensors based on on-chip hydrothermally grown 1-D zinc oxide (ZnO) nanostructures are presented, to improve the sensitivity, selectivity, and stability of the gas sensors.

Metal-oxide-semiconductor (MOS) gas sensors are well-established tools for the monitoring of air quality indoors and outdoors. In recent years, the use of 1-D metal oxide nanostructures for sensing toxic gases, such as nitrogen dioxide, ammonia, and hydrogen, has gained significant attention. However, low-dimensional nanorod (NR) gas sensors can be enhanced further. Most works synthesize the NRs first and then transfer them onto electrodes to produce gas sensors, thereby resulting in large batch-to-batch difference.

Therefore, in this thesis six studies on 1-D ZnO NR gas sensors were carried out. First, ultrathin secondary ZnO nanowires (NWs) were successfully grown on a silicon substrate. Second, an on-chip hydrothermally grown ZnO NR gas sensor was developed on a glass substrate. Its performance with regard to sensing nitrogen dioxide and three reductive gases, namely, ethanol, hydrogen, and ammonia, was tested. Third, three 1-D ZnO nanostructures, namely, ZnO NRs, dense ZnO NWs, and sparse ZnO NWs, were synthesized and tested toward nitrogen dioxide. Fourth, hydrothermally grown ZnO NRs, chemical vapor deposited ZnO NWs, and thermal deposited ZnO nanoparticles (NPs) were tested toward ethanol. Fifth, the effect of annealing on the sensitivity and stability of ZnO NR gas sensors was examined. Sixth, ZnO NRs were decorated with palladium oxide NPs and tested toward hydrogen at high temperature.

The following conclusions can be drawn from the work in this thesis: 1) ZnO NWs can be obtained by using a precursor at low concentration, temperature of 90 °C, and long reaction time. 2) ZnO NR gas sensors have better selectivity to nitrogen dioxide compared with ethanol, ammonia, and hydrogen. 3) Sparse ZnO NWs are highly sensitive to nitrogen dioxide compared with dense ZnO NWs and ZnO NRs. 4) ZnO NPs have the highest sensitivity to ethanol compared with dense ZnO NWs and ZnO NRs. The sensitivity of the NPs is due to their small grain sizes and large surface areas. 5) ZnO NRs annealed at 600 °C have lower sensitivity toward nitrogen dioxide but higher long-term stability compared with those annealed at 400 °C. 6) When decorated with palladium oxide, both materials form alloy at a temperature higher than 350 °C and decrease the amount of ZnO, which is the sensing material toward hydrogen. Thus, controlling the amount of palladium oxide on ZnO NRs is necessary.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. 60 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1513
Keyword
gas sensor, zinc oxide, on-chip, hydrothermal growth, nanorods, nanowires, annealing, palladium oxide, photoluminescence, alloy, sensitivity, selectivity, stability
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:uu:diva-320183 (URN)978-91-554-9908-2 (ISBN)
Public defence
2017-06-09, 2001, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2017-05-16 Created: 2017-04-17 Last updated: 2017-06-07

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