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 SnO2-coated multiwalled nanotubes (MWNTs), in which MWNT bundles are uniformly coated with a monolayer of SnO2 nanoparticles (∼4 nm). A hybrid SnO2 material combined with 0.1% wt MWNTs is fabricated and its CO gas-sensing properties are evaluated. SnO2-coated MWNTs are homogeneously distributed in the SnO2 matrix and the specific surface area of the hybrid material is nearly two times higher compared to pure SnO2 material. The electrical resistance is found to be dramatically decreased by three orders of magnitude compared to a conventional SnO2 sensor. The CO gas sensitivity is found to be three times higher than that of a SnO2 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/SnO2 material