کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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743049 | 1462107 | 2013 | 12 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Effects of polytetrafluoroethylene or polyimide coating on H2 sensing properties of anodized TiO2 films equipped with Pd–Pt electrodes Effects of polytetrafluoroethylene or polyimide coating on H2 sensing properties of anodized TiO2 films equipped with Pd–Pt electrodes](/preview/png/743049.png)
Diode-type H2 sensors based on anodically oxidized TiO2 thin films equipped with Pd–Pt electrodes (Pd–Pt/T-TiO2, T-TiO2 represents the TiO2 thin film fabricated by the anodization of the pre-oxidized Ti plate at 600 °C for 1 h in air) have been fabricated, and the effects of the polymer coating on the Pd–Pt/T-TiO2 sensor to humidity and oxygen partial pressure on the sensing properties to 500–8000 ppm H2 under dry and wet atmospheres have been investigated in this study. The films tested were polytetrafluoroethylene (PTFE), polyimide (PI) film and heterogeneously laminated layers of these two polymer films, and the sensors fabricated were referred to as P-n/Pd–Pt/T-TiO2 or P1-n/P2-n/Pd–Pt/T-TiO2 (P, P1 and P2: PTFE or PI, n: polymer concentration of the coating solution (wt%)). The H2 response of almost all sensors in wet air was larger than that in dry air, while the PTFE-n/Pd–Pt/T-TiO2 and PI-n/PTFE-n/Pd–Pt/T-TiO2 sensors showed only a slight enhancement in the H2 response by introduction of moisture, in comparison with the Pd–Pt/T-TiO2 or PI-n/Pd–Pt/T-TiO2 sensors. On the other hand, the H2 response of all sensors in N2 was not affected by humidity. The PI-10/Pd–Pt/T-TiO2 sensor showed the largest H2 response in air at 250 °C as well as N2 among the all sensors tested; the response of the sensors in dry air and dry N2 were ca. 3.1 × 10−4 A and ca. 4.7 × 10−2 A, respectively, where the sensor current in H2 atmosphere was regarded as sensor response, since that in the atmosphere without H2 was extremely small. In addition, the H2 response of the Pd–Pt/T-TiO2, PTFE-20/Pd–Pt/T-TiO2 and PI-20/Pd–Pt/T-TiO2 sensors were almost proportional to the H2 concentration in a lower concentration range (500–2000 ppm) in both dry and wet air, while it tended to saturate at a higher concentration range, especially for the PI-20/Pd–Pt/T-TiO2 sensor in wet air. On the other hand, the sensor response to H2 is well proportional to the logarithm of H2 concentration in both dry and wet N2 in the whole concentration range. Thus, the direct coating of the PTFE-n film on the Pd–Pt/T-TiO2 sensors reduced the effect of humidity on the H2 response and the direct coating of the PI-n film on the Pd–Pt/T-TiO2 sensors was effective for enhancing the H2 response.
Journal: Sensors and Actuators B: Chemical - Volume 183, 5 July 2013, Pages 253–264