A simple sol-gel method was applied for the synthesis of 0.01 wt% multiwalled carbon nanotubes (MWCNTs)-doped TiO 2 xerogel composite film. The film's CO gas sensing properties were then evaluated. Doped MWCNTs were coated with TiO 2 and distributed on a TiO 2 xerogel matrix. The TiO 2 xerogel showed an anatase structure after heat treatment at 450 °C under vacuum. The specific surface area of the composite material was larger than the pure TiO 2 xerogel material. The CO gas sensitivity of the MWCNTs(0.01 wt%)-doped TiO 2 xerogel composite film was found to be seven times higher than that of pure TiO 2 xerogel film and to have good stability. This higher gas-sensing property of the composite film was due to both an increase of specific surface area and the n-p junction structure of the TiO 2 xerogel coated on MWCNTs. The electrons generated from TiO 2 after adsorption of CO gas induces electron transfer from the TiO 2 to the MWCNTs. This induces a characteristic change in the MWCNTs from p-type to n-type, and the resistance of MWCNTs-doped TiO 2 xerogel composite sensor is therefore decreased.
All Science Journal Classification (ASJC) codes
- Surfaces, Coatings and Films