Preparation And Gas Sensing Properties Of PANI-based Nanocomposites

As one of the important conductive polymers,polyaniline(PANI)has been widely used in the field of gas sensors because of its advantages such as low manufacturing cost,good conductivity,good stability and good workability.As a gas sensor,pure-phase polyaniline sensing materials have problems such as a single morphology,low sensitivity and detection limit.It is an effective way to solve the above problems by improving the crystallinity and surface activity of PANI materials and compounding with oxides.However,the currently reported PANI and oxide composite materials exhibit the response characteristics of polyaniline during the gas sensitivity test,and the sensitivity is low,and the response recovery speed is slow.Therefore,it is of great significance to develop the preparation method of high crystallinity PANI-based materials and the controllable construction of PANI composite materials.This paper designs and synthesizes high crystallinity PANI nanosheet arrays,forest-like PANI/TiO₂nanocomposites and PANI/ZnO nanocomposites.XRD,XPS,SEM,TEM and other methods are used to analyze the PANI-based nanocomposite materials,and the materials are applied to gas sensor research,which can be used for detection Toxic and harmful gases such as NH₃,DMA and NO₂,and the sensitive mechanism is discussed.The content of this article is divided into the following three parts:(1)The PANI nanosheet array material with high crystallinity was synthesized by a simple gas phase diffusion method.We Assembled the materials into gas-sensing components,and tested the gas-sensitivity performance of different gases.The results show that the sensitivity of the PANI sensor is 6.69 at room temperature when the NH₃is 100 ppm,and the lowest detection limit is 100 ppb.The results have a good linear relationship.(2)Using tetrabutyl titanate as the titanium source and water as the solvent,synthesize TiO₂nanorod arrays by a simple hydrothermal method,and synthesize PANI/TiO₂nanocomposites by gas phase diffusion,and assemble the materials into gas sensors.The gas sensitivity test results show that the sensitivity of the PANI/TiO₂sensor to 30 ppm DMA gas at room temperature is 6.36,and the lowest detection limit is 50 ppb,and the material exhibits the response characteristics of a TiO₂n-type semiconductor.(3)Using zinc acetate as the zinc source and water as the solvent,ZnO nanosheet arrays were synthesized by the hydrothermal method.On this basis,PANI/ZnO nanocomposites were synthesized by the gas phase diffusion method.The materials are assembled into gas-sensing components,and the gas-sensitive performance of toxic and harmful NO₂gas is tested.The results show that the gas sensitivity of the ZnO nanosheet array combined with PANI is significantly improved.The sensitivity to 10ppm NO₂at room temperature is 28,the minimum detection limit is 10 ppb,and there is a good corresponding relationship to different concentrations of NO₂.It will promote the application of low temperature detection of semiconductor sensors.