Study On The Preparation Of Polyaniline-based Nanomaterials And Their Ammonia Sensitivity

Ammonia is a colorless and irritating odor gas,excessive inhalation of ammonia can cause respiratory problems in the human body.35 ppm ammonia will carry a risk to human health within just 15 minutes.Therefore,it is critical to develop new material sensors that have high sensitivity,good selectivity,low detection limits,and can operate in a room temperature environment.Polyaniline?PANI?,as one of conductive polymers,has many advantages such as low manufacturing cost,good plasticity,good thermal stability,simple synthesis,and it shows a broad application prospects in the field of ammonia gas detection at room temperature.Moreover,PANI-based material is easier to grow on flexible substrates than metal oxide material to form flexible material.This flexible,electrically conductive PANI-based material is more advantageous for use in the field of wearable,portable gas sensors.In this paper,PANI-based nanomaterials were prepared by one-step hydrothermal synthesis and gas phase diffusion,and the microstructure and morphology of the materials were characterized by X-ray diffraction?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?and Raman spectroscopy?Raman?.The gas sensitivity of PANI-based materials sensors to detect ammonia at room temperature is also discussed.The research content of this paper mainly includes the following aspects:Initially,PANI/TiO₂ and PANI/Fe₂O₃ nanocomposites materials powders were synthesized by one-step hydrothermal method.At room temperature,these both materials sensors have a good response to NH₃.The responses of two sensors are 5.423and 3.79,the detection limits are 0.5 ppm and 0.3 ppm,respectively.What's more,in order to improve the gas sensitivity,the PANI/Fe₂O₃ nanocomposites was directly grown on a flexible substrate by hydrothermal method to make a flexible sensor.This flexible sensor can be directly applied to the detection of ammonia at room temperature,and the response to 100 ppm ammonia is increased to 6.12.And the bending of the film has less influence on the gas sensing performance of the sensor.Based on the above research,it is found that the flexible and conductive film is good for the improvement of gas sensitivity.Therefore,we prepared a 2D PANI film material by gas phase diffusion at a low temperature.This material has a thinner layer,higher crystallinity and better gas sensitivity to ammonia.The response of PANI flexible film sensor is up to 12.8,and the detection limit is as low as 50 ppb.