Polyaniline/Graphene Coated Polyacrylonitrile Fabric To Prepare Wearable Ammonia Sensor

Ammonia?NH3?is a toxic gas,the inhalation of that may cause various acute respiratory diseases.Therefore,it is the general trend to develop an ammonia sensor with low power consumption,good selectivity,high sensitivity and good stability.As the core of the sensor,ammonia-sensitive materials are extremely important for in-depth research.Polyaniline?PANI?is a conductive sensing polymer,and its excellent doping/dedoping properties are widely used in ammonia-sensitive sensors.,Has a good response to NH3.Graphene,a two-dimensional material,has excellent electrical conductivity,physicochemical properties,and chemical stability.It can improve sensor performance to a certain extent,and is one of the ideal candidate materials for gas sensing.It can be improved by combining with PANI Sensing performance.The matrix material is also very important.After slight hydrolysis of polyacrylonitrile?PAN?filament fabric,a certain amount of carboxyl groups will be produced on the surface of the fabric,which is easy to modify and becomes one of the best choices for composite substrates.Generally speaking,the preparation of PAN-based sensing fabric is divided into two steps:first,the coating of aniline?An?monomer,and second,the polymerization of An monomer on the fabric.Because the bonding force between PANI and the substrate is van der Waals force,the bonding force is weak,the coating efficiency is low,and the load rate is low.In view of this,in order to improve the load and firmness of PANI,this experiment aims to explore a new coating method and conduct a series of studies on its gas sensing performance.The main content and conclusion of the paper are as follows:?1?The alkaline method is used to hydrolyze the surface of the PAN filament fabric to a certain degree,so that certain functional groups such as carboxyl groups and amide groups are generated on the surface.The PANI is coated by electrostatic adsorption to control the hydrolysis temperature and other variables.Response performance,determine the best hydrolysis process,using infrared spectroscopy,electron microscopy and digital multimeter method to characterize the structure and electrical conductivity of the prepared sensor fabric.Data analysis shows that the best preparation condition for fabric treatment is hydrolysis in 8 wt%NaOH at 90?for 2 h.When the concentration ratio of An monomer to initiator is 1:1,the hydrochloric acid doping concentration is 1 mol/L,at this time,the coating effect of PANI is the best,and it has a higher response value?100 ppm NH₃,the sensitivity is about 1000%?,and the recovery time is faster?the response speed is faster than the hydrolysis at 90?for 1 h by 29%,The recovery speed is increased by 31%?,it has better stability after multiple measurements,its response value under different NH₃concentrations shows good linearity?R=0.997?,and bending test shows that the device has good Mechanical properties and bending resistance,washing test proves that its washing resistance has been greatly improved?resistivity only increased by 8.8%after 10 times of 30 min washing?.?2?Polymerize aniline monomer?An?on the surface of GO to prepare PANI/GO composite coating.Infrared spectroscopy,Raman spectroscopy,electron microscopy and digital multimeter method were used to characterize the structure and sensing performance of the prepared sensing fabric.Using FT-IR and SEM to analyze the structure and morphology of the PANI/GO composite coating,it was found that PANI formed a nanorod array on the GO nanosheet,and the reduction degree of rGO was characterized by Raman?ID/IG=1.27?.The sensing performance of PAN/GO/PANI and PAN/rGO/PANI fabrics is analyzed,and the sensing mechanism is analyzed.The results show that PAN/GO/PANI has a high response value?2100%?at 100 ppm NH₃,and PAN/rGO/PANI has a higher response speed?63 s?and recovery speed?34 s?;in addition,we have also studied The mechanism of the effect of GO and rGO on PANI sensing performance is discussed,and the promotion effect of pn heterojunction on sensing performance is discussed.The above research provides a new preparation method for wearable flexible sensors,which is simple,fast,efficient,and has good stability.Therefore,the preparation method has broad application prospects in flexible sensors and room temperature gas detection products.