A comparison of the gas sensing properties of purified and platinum decorated chemical vapour deposition grown multi walled carbon nanotubes

Multi walled carbon nanotubes (MWCNTs) are known to respond well to a range of gases and vapours. Metallic additives are often introduced to improve the sensitivity and selectivity to some gases. Here the difference in response between MWCNT sensors with and without a metal additive is discussed for a range of gases. Resistive sensors fabricated from chemical vapour deposition (CVD) grown multi walled carbon nanotubes (MWCNTs) collected between gold microelectrodes by di-electrophoresis are presented as a cheap, scaleable and facile method of producing carbon nanotube gas sensors. The MWCNTs sensors were exposed to a series of test gases including NO2, NH3, CO and H2 and exhibited low ppm. detection at room temperature. Increasing the temperature not only reduced the recovery time of the sensors, but also increased the sensitivity to some gases whilst a decrease in the sensitivity was seen for other gases. A method for decorating MWCNTs with nanometer sized Pt particles is presented and compared as a sensing material to purified MWCNTs which have undergone acid reflux and base washing. The role of defects and the sensing mechanisms are discussed. © 2008 Springer-Verlag Berlin Heidelberg.