Room temperature gas sensor based on tin dioxide-carbon nanotubes composite films

Chemical sensors based on tin dioxide-carbon nanotubes (SnO2-CNT) composite films were fabricated by hot filament chemical vapor deposition (HF-CVD) technique. The composite films consist of SnO2 nanoparticles highly dispersed on the CNTs surface. Their resistivity is highly sensitive to the presence of adsorbates, which become easily attached or detached at room temperature and ambient pressure depending on their gas phase concentration. We systematically studied the sensitivity of the SnO2-CNT composite films for ethanol, methanol and H2S. The results were also compared to those for SnO2 and CNTs separately. It is shown that the SnO2-CNT composite films can detect ethanol, methanol and H2S down to ppm levels below OSHA's permissible exposure limits at room temperature and ambient pressure. Moreover, they self-recover within 1 min without requiring any heating or energy source.