Using a TiO₂/ZnO double-layer film for improving the sensing performance of ZnO based NO gas sensor

NO gas sensors, based on ZnO thin film (ZnOfᵢₗₘ), TiO₂ nanoparticulate film (TiO₂NP), and TiO₂NP/ZnOfᵢₗₘ double-layer film, were fabricated, and their sensing characteristics towards NO gas were investigated in this study. The maximal response of a ZnOfᵢₗₘ deposited onto a rougher Al₂O₃ substrate, t...

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Veröffentlicht in:Sensors and actuators. B, Chemical Chemical, 2011-10, Vol.157 (2), p.361-367
Hauptverfasser: Lin, Chia-Yu, Chen, Jiang-Ging, Feng, Wei-Yi, Lin, Chii-Wann, Huang, Ju-Wen, Tunney, James J, Ho, Kuo-Chuan
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Sprache:eng
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Zusammenfassung:NO gas sensors, based on ZnO thin film (ZnOfᵢₗₘ), TiO₂ nanoparticulate film (TiO₂NP), and TiO₂NP/ZnOfᵢₗₘ double-layer film, were fabricated, and their sensing characteristics towards NO gas were investigated in this study. The maximal response of a ZnOfᵢₗₘ deposited onto a rougher Al₂O₃ substrate, towards NO gas, was higher than that of a ZnOfᵢₗₘ deposited on a smoother glass substrate. Although the sensing response of the TiO₂NPs itself towards NO gas was minute, the TiO₂NP/ZnOfᵢₗₘ double-layer film showed enhanced response as compared with TiO₂NP or ZnOfᵢₗₘ single-layer film. In addition, the sensor response of the TiO₂NP/ZnOfᵢₗₘ double-layer film was strongly influenced by the annealing time for the film preparation; the maximum response to NO was enhanced about 6.2 times as the annealing time was increased from 30min to 2h. Based on the XPS results, the increase in the transition zone between TiO₂NP and ZnOfᵢₗₘ along with the appearance of Ti³⁺ state was noticed when the annealing time was increased. With the high sensitive TiO₂NP/ZnOfᵢₗₘ/Al₂O₃ electrode, the limit of detection (S/N=3) can be achieved at 8.8ppb. The double-layer TiO₂NP/ZnOfᵢₗₘ also showed improved selectivities with respect to NO₂ and CO.
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2011.04.056