CO sensing performance in micro-arc oxidized TiO2 films for air quality control

Porous TiO2 films were prepared by the micro-arc oxidation (MAO) of Ti plates, and their CO sensing properties at low concentrations (5-100ppm) were investigated as an application for an air quality control sensor. The obtained rutile films exhibited the maximum CO gas response at 350°C, which is typical for semiconductor-type gas sensors, and the Ra/Rg was 1.6 for 10ppm CO (Ra: resistance in air, Rg: resistance in a sample gas). The magnitude of the gas response increased almost linearly with increasing the CO concentration from 5 to 100ppm. The CO sensing performance of the TiO2 sensor in the presence of humidity was investigated and compared with that of a SnO2 sensor.