Electrospun CNT Composite Nanofibers And Study On Gas Sensitivity

With the rapid development of modern industrial technology,ammonia can be seen everywhere in people's daily life and industrial production.Long term exposure to excessive ammonia can cause respiratory tract,skin burns,chest tightness,shortness of breath and other health problems.Therefore,there is an urgent need for a gas sensor which can quickly and effectively detect ammonia.In recent years,CNT has become an ideal room temperature gas sensitive material.However,the gas sensor made of CNT has some disadvantages,such as low efficiency,long response time(about 5-20min),complex preparation process and so on.In order to increase the gas sensing performance of CNT,it is hoped that CNT can be combined with conductive polymer with high conductivity and high response.Compared with other methods of preparing composite materials,the gas sensing film prepared by electrospinning method has the advantages of large specific surface area,good flexibility and bending,which is very suitable for the current popular flexible wearable sensors.Therefore,in this paper,CNTs are taken as the basic research object,two kinds of conductive polymers and multi walled carbon nanotubes are electrospun into nanofiber films by electrospinning equipment,which are carried on the interdigital electrode to make gas sensors.Through experimental comparison,it is found that they can effectively monitor ammonia.The specific research contents are as follows:Firstly,an electrospinning equipment was built independently.The electrostatic field during spinning was simulated by COMSOL software,and the reasonable width of collecting plate was selected.According to the simulation results,the relationship between voltage,spinning distance and electric field intensity was analyzed.Secondly,the MWCNT used in the spinning process were treated by mixed acid oxidation to improve the aggregation of CNTs in solution.Then,PVA / PEDOT / CNT and pan / PANI / CNT composite films were prepared by electrospinning method.SEM images of different electrospinning parameters were taken respectively,and the distribution map of 100 fiber diameter in selected area was drawn by image processing software,so as to select the optimal electrospinning parameters.Finally,the two kinds of composite films were carried on the finger electrode respectively to study their gas sensing characteristics.It is found through experiments that the ammonia selectivity and stability of the two composite films are very good,and can effectively detect ammonia above 20 ppm.The sensitivity of the sensor prepared by composite material is 3.15 times higher than that of single component;The sensor prepared by pan/pani/cnt has shorter response recovery time.