Simple point contact WO3 sensor for NO2 sensing and relevant impedance analysis |
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Authors: | Wu-bin Gao Yun-han Ling Xu Liu Jia-lin Sun |
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Institution: | 1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing, 100083, China 2. Department of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China
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Abstract: | A simple and new point contact tungsten trioxide (WO3) sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration (ppm level) environmental pollutants such as NO2. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were applied to characterize the phase and the microstructure of the samples, respectively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor (W-WO3-W) showed rectifying characteristics and an ideal sensing performance of about 110°C. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy (EIS) at a relatively low temperature of 150°C but faded away above 200°C, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site. |
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