TiO2 -WO3 and Graphene / PPy Composite Applications in Humidity Sensor

• Main Authors: Lin, Wangde, 林旺德
• Other Authors: Wu, Renjang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/68116665216837838774

博士 === 靜宜大學 === 應用化學系 === 101 === Humidity sensor application is quite extensive, including agricultural production, pharmaceutical manufacturing, electronic component production, food preservation and other aspects of the need for strict control of humidity. While the ceramic humidity sensor and the polymer humidity sensor, the former has a good thermal and chemical stability; the latter, which has the advantage of high sensitivity, being manufactured easily and low cost, etc., has great development potential. In this study, we use the formation of different composite materials from the metal oxide (TiO2-WO3) and the polymers (graphene / PPy) as humidity sensors respectively, then their surface characteristics and properties and the the sense of the humidity are studied as well. A novel TiO2-WO3 composite material was prepared in a different proportion of TiO2 and WO3. The obtained mesoporous material was characterized by XRD (X-ray diffraction), FTIR (Fourier transform infrared), TEM (Transmission electron microscopy), and N2 adsorption-desorption technology. The humidity sensing properties were measured by using LCR (Inductance, capacitance and resistance) analyzer system. The results exhibited that the sample with TiO2-WO3 (1:1) showed better humidity sensing properties than others within the range of 12-90 % relative humidity (RH), the response and recovery time were about 20 s and 160 s, respectively. Compared to the previous studies, the prepared sensor exhibits higher sensitivity (S=451) and the low hysteresis value was around 0.13% at 32% RH. Complex impedance analysis indicated that the enhanced humidity sensitivity was probably due to with spherical the large BET surface area and hetero-junction between TiO2-WO3 thin films, while the impedance varying about three orders of magnitude. Our results demonstrated the potential application of TiO2-WO3 composite for fabricating high performance humidity sensors. A novel sensing graphene/polypyrrole (PPy) material was prepared by a chemical oxidative polymer-ization method with various weight percentages of graphene. The structure and morphology were characterized by XRD (X-ray diffraction), FTIR (Fourier transform infrared), TEM (transmission electron microscopy), UV–vis spectrometry and TGA (thermo-gravimetric analysis). The humidity sensing proper-ties were measured by using an LCR (inductance, capacitance and resistance) analyzer. The results indicate that the sample with 10% graphene/PPy had better humidity sensing properties than the other samples at relative humidity (RH) in the range 12–90%. The response and recovery times were approximately 15 s and 20 s, respectively. The prepared sensor has a higher sensitivity (S = 138) than those developed elsewhere and the humidity hysteresis value was very small at all humidities (<0.16%). The results herein demonstrate the potential of graphene/PPy composite for use in fabricating high-performance humidity sensors.