Research On The Gas Sensing Properties Of Double-Walled Carbon Nanotubes

The research level and the application degree of nano-devices symbolize a national nano-science and technology total level. However, the device research based on carbon nanotube is an extremely important area in nano-devices research.The electronic structure and the property of electricity of carbon nanotube depend on its microstructure. For example, the different degree of spiral may cause its property of electricity from metal to semiconductor.In addition, the property of electricity of carbon nanotube also sensitively relies on its environment, the adsorption of gas molecules affects its propoerty of electricity. Based on this, the high sensitivity, the high selective nano gas sensors may be constructed. In this paper, we take double-walled carbon nanotubes as the object of study, and find out its property of gas adsorption and new sensing property to study its new property of electronic structure and new nano sensing devices.Double-walled carbon nanotubes have been synthesized by fluctuation catalyst chemical vapor deposition in this paper. Then, sensor device based on simple double-walled carbon nanotube was constructed by the technologies of supersonic dispersion,high speed centrifugal purification, deep ultraviolet submicron lithography craft, vacuum coating, and so on. The computer is connected to the precision instrument 2602 of American Keithley company by GPIB data bus. The test of gas sensing device will be automatic controlled by the computer, because of using the concept of virtual instrument and utilizing the LabVIEW to programme.The property of electricity of metal double-walled carbon nanotubes gas sensors and semiconductor double-walled carbon nanotubes gas sensors under differen atmosphere , different illumination and different gas adsorption, such as 0₂, H₂O₂, NO₂, NH₃, have been discussed. The experimental results show that the conductivity of double-walled carbon nanotubes is more changeable and more sensitive to gas. In the end, the encountered problems have been analysed in the test and the prospect of the sensors has been discussed.