Research Of Gas Sensor Based On Carbon Nanotubes And The Effects Of Palladium And Copper Doping

As one of the perfect one-dimensional nano-materials, carbon nanotube has porous microstructure with high surface area and energy, which makes it a promising gas sensing material. In this paper, the preparation and characteristic of gas sensor based on carbon nanotubes for formaldehyde, benzene, toluene and xylene detection were discussed. When the organic volatile compound gas molecule is adsorbed in the carbon nanotubes film, the conductivity of the sensing film changes. The concentration of the gas could be achieved by measuring the change of the conductivity. In the experiments, the gas sensor was prepared by spreading the water solution of carbon nanotubes between the interdigitated Au electrode, which was splashed on alumina. In this paper, three methods, such as mixing palladium and copper chloride, deoxidizing palladium and copper by chemical and electrochemical means, were used to doping palladium and copper in multi-wall carbon nanotubes. The effect of doping on the characteristic of the gas sensor was studied. The sensor was sensitive to formaldehyde, benzene, toluene and xylene, whose concentration was as low as 10ppm. The sensitivity of the gas sensor was improved by different doping methods, especially by chemically doping palladium and electrochemically doping copper.The size and uniformity of the doped metal grain were found important to the doping effects. In this paper, two ways of chemical copper doping were studied, which indicate that sensitivity of the gas sensor can be improved by small grain size and uniformly doping. Different electric charge of electroplating was studied in electrochemical doping, it was found that the response of gas sensor was high when the electroplating charge is 10mC.