Preparation Of Carbon Nanotube Array Composite And Its Application As A Gas Sensor

Carbon nanotube has a large specific surface area,a unique hollow structure.Its good electrical properties attribute to the graphite sheet structure,therefore carbon nanotube is widely used in sensor field.At present,the research on carbon nanotube based gas sensors is focused on random-oriented carbon nanotube.However,the carbon nanotube array has a high orientation,which plays a critical role in sensing performance.Conductive polymer polyaniline has the characteristics of insulation and the electrical properties of the metal,the unique redox adjustable performance,good environmental stability,low cost and easy synthesis,etc.It also has a excellent sensitivity to acid and alkali gas.It has shown great potentials for applications in sensing devices.This paper presents a method for preparing carbon nanotube array/polyaniline composites,which have the characteristics of simple operation and low cost.Using the experimental method of preparation of porous scaffolds by silk fibroin solution,which is dropping the silk fibroin solution into the carbon nanotube array prepared by chemical vapor deposition method,the carbon nanotube array with original orientation and structures is obtained.Then,the array is modified with polyaniline by using electrochemical method.The composites are characterized by scanning electron microscopy,infrared spectroscopy and raman spectroscopy.The response sensitivities of carbon nanotube array to ammonia and hydrogen chloride are higher than that of random-oriented carbon nanotube,and the response sensitivity of carbon nanotube array modified with polyaniline is better than that of carbon nanotube array.The sensitivity of the carbon nanotube array/polyaniline composite material is 2.9% in the 50 ppm ammonia gas and 4.1% in the 200 ppm hydrogen chloride atmosphere.To investigate the selectivity of carbon nanotube arrays/polyaniline composites to gases,this paper also conducts a gas-sensing test on organic gases including acetone,ethyl acetate and methanol.The results show that the sensors show responses to these organic gases and have good sensitivity to ammonia and hydrogen chloride.