Effect of Humid Aging on the Oxygen Adsorption in SnO2 Gas Sensors
Koichi Suematsu 1,*
, Nan Ma 2,†, Ken Watanabe 1, Masayoshi Yuasa 1,‡, Tetsuya Kida 1,§ and Kengo Shimanoe 1
, Nan Ma 2,†, Ken Watanabe 1, Masayoshi Yuasa 1,‡, Tetsuya Kida 1,§ and Kengo Shimanoe 1
1
Department of Advanced Materials Science and Engineering, Faculty of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
2
Department of Molecular and Material Science, Interdisciplinary Graduate School of Engineering Science, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
*
Author to whom correspondence should be addressed.
†
Present address: Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Science, Beijing 100083, China.
‡
Present address: Department of Biological and Environmental Chemistry, School of Humanity-Oriented Science and Engineering, Kinki University, Iizuka, Fukuoka 820-8555, Japan.
§
Present address: Department of Applied Chemistry and Biochemistry, Kumamoto University, Kumamoto 860-8555, Japan.
Sensors 2018, 18(1), 254; https://doi.org/10.3390/s18010254
Received: 18 December 2017 / Revised: 10 January 2018 / Accepted: 11 January 2018 / Published: 16 January 2018
(This article belongs to the Special Issue Gas Sensors based on Semiconducting Metal Oxides)
Abstract
To investigate the effect of aging at 580 °C in wet air (humid aging) on the oxygen adsorption on the surface of SnO2 particles, the electric properties and the sensor response to hydrogen in dry and humid atmospheres for SnO2 resistive-type gas sensors were evaluated. The electric resistance in dry and wet atmospheres at 350 °C was strongly increased by humid aging. From the results of oxygen partial pressure dependence of the electric resistance, the oxygen adsorption equilibrium constants (K1; for O− adsorption, K2; for O2− adsorption) were estimated on the basis of the theoretical model of oxygen adsorption. The K1 and K2 in dry and wet atmospheres at 350 °C were increased by humid aging at 580 °C, indicating an increase in the adsorption amount of both O− and O2−. These results suggest that hydroxyl poisoning on the oxygen adsorption is suppressed by humid aging. The sensor response to hydrogen in dry and wet atmosphere at 350 °C was clearly improved by humid aging. Such an improvement of the sensor response seems to be caused by increasing the oxygen adsorption amount. Thus, the humid aging offers an effective way to improve the sensor response of SnO2 resistive-type gas sensors in dry and wet atmospheres. View Full-TextKeywords:
SnO2; gas sensors; humid aging; oxygen adsorption; hydroxyl poisoning; hydrogen sensing
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Suematsu, K.; Ma, N.; Watanabe, K.; Yuasa, M.; Kida, T.; Shimanoe, K. Effect of Humid Aging on the Oxygen Adsorption in SnO2 Gas Sensors. Sensors 2018, 18, 254.
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