The effect of multiwalled carbon nanotube doping on the CO gas sensitivity of SnO₂-based nanomaterials

A simple in situ method is applied for the synthesis of SnO 2 -coated multiwalled nanotubes (MWNTs), in which MWNT bundles are uniformly coated with a monolayer of SnO 2 nanoparticles (∼4 nm). A hybrid SnO 2 material combined with 0.1% wt MWNTs is fabricated and its CO gas-sensing properties are evaluated. SnO 2 -coated MWNTs are homogeneously distributed in the SnO 2 matrix and the specific surface area of the hybrid material is nearly two times higher compared to pure SnO 2 material. The electrical resistance is found to be dramatically decreased by three orders of magnitude compared to a conventional SnO 2 sensor. The CO gas sensitivity is found to be three times higher than that of a SnO 2 sensor, with good stability, indicating that the addition of 0.1% wt MWNTs is effective in improving the sensitivity towards CO. A model is proposed to explain the improvement of CO gas sensitivity for our hybrid MWNT/SnO 2 material.