Carbon dioxide resistive sensor based on titanium oxide nanowires doped with potassium

Potassium-doped titanium oxide (TiO₂) nanowires are fabricated by the moisture-assisted, direct oxidation of a thin film of titanium at 650°C. The influence of the fabrication conditions on the structure and morphology of the nanowires was investigated. It was shown that the presence of potassium (K) is necessary for the formation of the nanowires. The density of growth of the nanowires was high, and the lengths of the nanowires were tens of micrometres. The K-doped TiO₂ nanowires showed the possibility of use as a sensing material because of their significant and consistent response to responding to carbon dioxide (CO₂) gas. In addition, H₂ plasma treatment improved the sensitivity of the CO₂ gas sensor made of K-doped TiO₂ nanowires. Although the sensing mechanism is not clear, this development suggests opportunities for the fabrication of simple and inexpensive CO₂ microsensors with low power consumption.