Ammonia Sensing Mechanism of Tungstated-Zirconia Thick Film Sensor
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- 作者：Atsushi Satsuma ; Ken-ichi Shimizu ; Koichi Kashiwagi ; Tadanori Endo ; Hiroyuki Nishiyama ; Shiro Kakimoto ; Satoshi Sugaya ; Hitoshi Yokoi
- 刊名：Journal of Physical Chemistry C
- 出版年：2007
- 出版时间：August 16, 2007
- 年：2007
- 卷：111
- 期：32
- 页码：12080 - 12085
- 全文大小：119K
- 年卷期：v.111,no.32(August 16, 2007)
- ISSN：1932-7455
文摘
A sensor element of interdigital capacitor (IDC) electrodes covering with tungstated-zirconia thick film showsa good response and cross-sensitivity in gaseous ammonia sensing. The sensing mechanism of the tungstated-zirconia thick film has been investigated by means of in situ FT/IR and H/D isotope effect. In the absenceof ammonia, the role of protonic conduction was clarified by the H/D isotope effect of water vapor on theconductivity. In the presence of gas phase ammonia, the conductivity of the tungstated-zirconia thick filmsignificantly increased. The conductivity in the presence of ammonia showed unique temperature dependence,i.e., the conductivity at first increased with a decrease in temperature, showed the maximum at 633 K,and then decreased with further decrease in temperature. In situ FT/IR spectra revealed the presence ofboth ammonium ion adsorbed on Br
nsted acid site and ammonia coordinated to Lewis acid site on thetungstated-zirconia surface. Temperature dependence and dynamic response of the conductivity were in goodaccordance with the surface concentration of ammonium ion adsorbed on Brnsted acid site. The contributionof ammonium ion to electric conductivity was indicated. The role of ammonium ion as a migrating speciesfor ammonia sensing was verified from negligible H/D isotope effect of ammonia and mobility of ammoniumion.
nsted acid site and ammonia coordinated to Lewis acid site on thetungstated-zirconia surface. Temperature dependence and dynamic response of the conductivity were in goodaccordance with the surface concentration of ammonium ion adsorbed on Brnsted acid site. The contributionof ammonium ion to electric conductivity was indicated. The role of ammonium ion as a migrating speciesfor ammonia sensing was verified from negligible H/D isotope effect of ammonia and mobility of ammoniumion.