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Title: Fabrication of highly selective tungsten oxide ammonia sensors

Abstract

Tungsten oxide is shown to be a very promising material for the fabrication of highly selective ammonia sensors. Films of WO{sub 3} were deposited onto a silicon substrate by means of the drop-coating method. Then, the films were annealed in dry air at two different temperatures (300 and 400 C). X-ray photoelectron spectroscopy was used to investigate the composition of the films. Tungsten appeared both in WO{sub 2} and WO{sub 3} oxidation states, but the second state was clearly dominant. Scanning electron microscopy results showed that the oxide was amorphous or nanocrystalline. The WO{sub 3}-based devices were sensitive to ammonia vapors when operated between 250 and 350 C. The optimal operating temperature for the highest sensitivity to ammonia was 300 C. Furthermore, when the devices were operated at 300 C, their sensitivity to other reducing species such as ethanol, methane, toluene, and water vapor was significantly lower, and this resulted in a high selectivity to ammonia. A model for the sensing mechanisms of the fabricated sensors is proposed.

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Univ. Rovira i Virgili, Tarragona (ES)
OSTI Identifier:
20023354
Resource Type:
Journal Article
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 147; Journal Issue: 2; Other Information: PBD: Feb 2000; Journal ID: ISSN 0013-4651
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 54 ENVIRONMENTAL SCIENCES; TUNGSTEN OXIDES; AMMONIA; AIR POLLUTION MONITORS; CHEMICAL COATING; ANNEALING; MORPHOLOGY; TEMPERATURE DEPENDENCE; PERFORMANCE; MATHEMATICAL MODELS

Citation Formats

Llobet, E, Molas, G, Molinas, P, Calderer, J, Vilanova, X, Brezmes, J, Sueiras, J E, and Correig, X. Fabrication of highly selective tungsten oxide ammonia sensors. United States: N. p., 2000. Web. doi:10.1149/1.1393270.
Llobet, E, Molas, G, Molinas, P, Calderer, J, Vilanova, X, Brezmes, J, Sueiras, J E, & Correig, X. Fabrication of highly selective tungsten oxide ammonia sensors. United States. https://doi.org/10.1149/1.1393270
Llobet, E, Molas, G, Molinas, P, Calderer, J, Vilanova, X, Brezmes, J, Sueiras, J E, and Correig, X. 2000. "Fabrication of highly selective tungsten oxide ammonia sensors". United States. https://doi.org/10.1149/1.1393270.
@article{osti_20023354,
title = {Fabrication of highly selective tungsten oxide ammonia sensors},
author = {Llobet, E and Molas, G and Molinas, P and Calderer, J and Vilanova, X and Brezmes, J and Sueiras, J E and Correig, X},
abstractNote = {Tungsten oxide is shown to be a very promising material for the fabrication of highly selective ammonia sensors. Films of WO{sub 3} were deposited onto a silicon substrate by means of the drop-coating method. Then, the films were annealed in dry air at two different temperatures (300 and 400 C). X-ray photoelectron spectroscopy was used to investigate the composition of the films. Tungsten appeared both in WO{sub 2} and WO{sub 3} oxidation states, but the second state was clearly dominant. Scanning electron microscopy results showed that the oxide was amorphous or nanocrystalline. The WO{sub 3}-based devices were sensitive to ammonia vapors when operated between 250 and 350 C. The optimal operating temperature for the highest sensitivity to ammonia was 300 C. Furthermore, when the devices were operated at 300 C, their sensitivity to other reducing species such as ethanol, methane, toluene, and water vapor was significantly lower, and this resulted in a high selectivity to ammonia. A model for the sensing mechanisms of the fabricated sensors is proposed.},
doi = {10.1149/1.1393270},
url = {https://www.osti.gov/biblio/20023354}, journal = {Journal of the Electrochemical Society},
issn = {0013-4651},
number = 2,
volume = 147,
place = {United States},
year = {Tue Feb 01 00:00:00 EST 2000},
month = {Tue Feb 01 00:00:00 EST 2000}
}