Study On PANI-MWCNTs Nanocomposite Room Temperature Flexible Ammonia Gas Sensor

The flexible gas sensor has the characteristics of room temperature detection,flexible bending,etc.,and can be applied to food detection,human health diagnosis and other fields.However,research on flexible gas sensor technology is still in the initial stage.Polyaniline(PANI)has become a research hotspot for flexible materials because of its strong flexibility and tensile strength.However,as a gas-sensitive material,PANI has a low gas-sensitivity response and poor gas-sensing recovery.Multi-walled carbon nanotubes(MWCNTs)are used to improve the gas-sensing response of composites.On the other hand,there are few reports on the influence of temperature and humidity on composite materials,and the research on temperature and humidity is not perfect.In this paper,the influence mechanism of different temperature and humidity on composites is studied in detail.In this paper,two methods are used to prepare composites.One is to prepare nanocomposites by in-situ polymerization,and the other is to use a layering process.Firstly,PANI-MWCNTs nanocomposite structures were prepared by in-situ polymerization method to form nanofiber structures with PANI uniformly encapsulated on the surface of MWCNTs.The effects of different reaction times on the gas-sensing response were mainly studied.The results showed that the polymerized 2h composites had the largest specific surface area and highest sensitivity.,shorten recovery time,improve baseline drift.The interaction between PANI and MWCNTs exists.The addition of MWCNTs improves the sensitivity and tensile strength of the gas-sensing response.A flexible,highly sensitive,selective,low-cost,room-temperatureresponsive ammonia gas sensor is available.The effect of different humidity(20%,40%,and 60%)on the ammonia-sensitive properties of the composites was tested.The results showed that the sensitivity of the ammonia-sensitive properties decreased with the increase of humidity,and the mechanism of humidity was affected.Improve the reaction efficiency,increase the utilization of materials and the dispersibility of MWCNTs,experiment adopt different layers of deposition process to prepare thin films.The gas sensitivity test results show that the first-rotated MWCNTs second-polymerized PANI(M?P)film has the highest sensitivity.The contact area is the largest,the interaction is the strongest,and it becomes a good interface contact.Next the gas-responsive response parameters of the gas-sensitive films prepared by the two processes are compared,and the advantages and disadvantages of the two processes were analyzed.Finally,the effects of humidity and temperature on the resistance of M?P hierarchical structure were tested,and the mechanism of the decrease of the resistance with the increase of humidity was analyzed from perspectives of the proton exchange and PANI conductivity models.Tested under relative humidity of 25% and relative humidity of 50%,the relationship between the resistance of M?P hierarchical structure at different temperatures,and the influence mechanism of the resistance increasing with increasing temperature was analyzed from the thermal expansion theory of PANI,and finally the room temperature operating conditions for the stable operation of the device were determined.In conclusion,this article studied in detail the performance of PANI and MWCNTs composites applied to flexible ammonia sensors,focusing on the gas-sensing response mechanism,and the influencing factors of temperature and humidity on composite membranes.