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Titolo:
SO2 sensing mechanism of Ag/WO3. Surface states and electronic interactions
Autore:
Shimizu, Y; Matsunaga, N; Hyodo, T; Egashira, M;
Indirizzi:
Nagasaki Univ, Fac Engn, Nagasaki 8528521, Japan Nagasaki Univ Nagasaki Japan 8528521 , Fac Engn, Nagasaki 8528521, Japan
Titolo Testata:
ELECTROCHEMISTRY
fascicolo: 2, volume: 69, anno: 2001,
pagine: 109 - 116
SICI:
1344-3542(200102)69:2<109:SSMOAS>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
GAS SENSORS; TIN DIOXIDE; ADSORPTION; XPS; ADDITIVES; OXYGEN;
Keywords:
SO2; semiconductor gas sensor; Ag/WO3; sensing mechanism;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Engineering, Computing & Technology
Citazioni:
14
Recensione:
Indirizzi per estratti:
Indirizzo: Shimizu, Y Kyushu Univ, Interdisciplinary Grad Sch Engn Sci, 6-1 Kasuga Koen, Kasuga,Fukuoka 8168580, Japan Kyushu Univ 6-1 Kasuga Koen Kasuga Fukuoka Japan 8168580 Japan
Citazione:
Y. Shimizu et al., "SO2 sensing mechanism of Ag/WO3. Surface states and electronic interactions", ELECTROCH, 69(2), 2001, pp. 109-116

Abstract

SO2 sensing properties of WO3 loaded with and without a metal have been investigated in the temperature range of 200-800 degreesC. X-ray photoelectron spectroscopic studies and temperature programmed desoprtion spectra from SO2-preadsorbed WO3-based sensor materials were also conducted to clarify the adsorption states of SO2 and their electronic interactions, and then to discuss the SO2 sensing mechanism. The resistance of WO3 increased upon exposure to SO2 at temperatures lower than 500 degreesC, due to the formation of SO2- (ad) at adsorption sites different from those for oxygen adsorbates. In contrast, the resistance of WO3 decreased in SO2 at temperatures higher than 550 degreesC, due to the formation of SO4ad2- by the reaction of a gaseous SO2 molecule and two O-ad(2-) adions. The largest resistance change of WO3 induced by SO2, i.e. the highest sensitivity, was observed at 400 degreesC. Among the metals tested, the addition of 1.0 wt% Ag resulted in themost significant enhancement in sensitivity at 450 degreesC, while the resistance decreased in SO2 over the whole temperature range studied. In the case of 1.0 Ag/WO3 the resistance was determined mainly by the sur-face state of Ag. It was considered that the formation of SO4ad2- was facilitated even at a temperature of 450 degreesC by the reaction of gaseous SO2 and O-ad(2-) on the Ag surface and that this caused the resistance decrease.

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Documento generato il 30/10/20 alle ore 09:36:47