Tailoring gas sensing properties of multi-walled carbon nanotubes by in situ modification with Si, P, and N

A simple method for the synthesis of multi-walled carbon nanotubes (MWCNTs) containing Si, P-N and N is reported, and their gas sensing properties were investigated. The MWCNTs were synthesised by the thermal decomposition of aerosols containing mixtures of ferrocene/triphenylsilane, ferrocene/triphenylphosphine/benzylamine, and ferrocene/benzylamine/toluene. Electron microscopy studies revealed that the addition of Si, P, and N alters the structure of CNTs dramatically. Gas sensing experiments were carried out using Si, P-N, N-containing MWCNTs, and were compared with pure MWCNTs synthesised at similar experimental conditions. These experiments showed that the gas sensitivity and selectivity of CNT-based sensors can be indeed tailored without any post-processing of the raw nanotubes. The efficient in situ tailoring of nanotube properties and functionality are important for nanotubes to become viable materials at the industrial scale where low cost processes are required.