TiO(2-x)/TiO(2)-Structure Based ‘Self-Heated’ Sensor for the Determination of Some Reducing Gases

In this research we report the gas-sensing properties of TiO(2-x)/TiO(2)-based hetero-structure, which was ‘self-heated’ by current that at constant potential passed through the structure. Amperometric measurements were applied for the evaluation of sensor response towards ethanol, methanol, n-propanol and acetone gases/vapours. The sensitivity towards these gases was based on electrical resistance changes, which were determined by amperometric measurements of current at fixed voltage applied between Pt-based contacts/electrodes deposited on the TiO(2-x)/TiO(2)-based layer. X-ray diffraction (XRD) analysis revealed the formation of TiO(2-x)/TiO(2)-based hetero-structure, which is mainly based on Ti(3)O(5)/TiO(2) formed during the hydro-thermal oxidation-based sensing-layer preparation process. Additionally, photoluminescence and time-resolved photoluminescence decay kinetics-based signals of this sensing structure revealed the presence of TiO(2) mainly in the anatase phase in the TiO(2-x)/TiO(2)-based hetero-structure, which was formed at 400 °C annealing temperature. The evaluation of TiO(2-x)/TiO(2)-based gas-sensing layer was performed at several different temperatures (25 °C, 72 °C, 150 °C, 180 °C) and at these temperatures different sensitivity to the aforementioned gaseous materials was determined.