One-step Hydrothermal Synthesis And Gas-sensing Properties Of Polyaniline/TiO₂Composites

Hazardous gas detection is important issue in environmental testing. Gas sensors are specifically testing device of gas species and content in an environment. The core components of gas sensors are gas sensing materials. Research and development of high performance gas-sensitive material has a profound effect on the development and ap-plication of gas sensor. Currently, the study of organic/inorganic compos-ite gas-sensitive materials is hot, but the preparation method is more complex.This thesis selected a good, broad application of TiO2and rich in raw materials and simple preparation of polyaniline (PANI), with com-pound means synthesized a new type of gas sensitive materials. Synthe-sized PANI/T1O2composites by hydrothermal method with raw material of TiOSO4·2H2O and C6H5NH2and studied on optimum synthesis condi-tions. Characterization of PNAI/TiO2composite materials used the means of X-ray diffracion、Fourier transform infrared, N2adsorp-tion-desorption、Scanning electron microscopy, X-ray photoelectron spectroscopy, etc. Then maked it into a gas sensor and studied on the properties of gas sensitivity to ammonia and ethanol, etc.Results showed that synthetic temperature of130℃, hot water6h, titanium sulphate with aniline monomer molar ratio for4:1is the optimal technological conditions of preparation of PANI/TiO2composites. Under the conditions, the synthesis of PANI/TiO2composites has good selectiv-ity to ammonia. When ammonia concentration is200ppm, PANI/TiO2composites’s sensitivity is0.95and response time is85s and recovery time is45s. When ammonia concentration is100ppm, the stability of PANI/TiO2composites reduced15%after ten days, and then tended to be stable. We simply introduced the gas sensing mechanism of PANI/TiO2composites by the network formed of p-n junction. The preparation process is simple because PANI/TiO2composites synthesized by hydrothermal method without addition of hydrochloric acid to provide acid environment and Proton acid doping. The materials have a high sensitivity and stability and short response time and recovery time to ammonia. So it has a certain practical value in environmental de-tection.