CO and C3H8 sensing performance of coatings obtained from TiO2-powders

Different semiconductor oxides have been widely studied for gas sensing applications. In this work, titanium dioxide (TiO2) powders, synthesized by the homogeneous precipitation method, have been used to deposit thick coatings over sodalime glass sustrates by using a simple and scalable chemical method, Doctor Blade. TiO2 powders were processed via the precipitation process from both titanium isopropoxide (TTI) and titanium butoxide (TiBu), separately, as Ti precursors. For processing the TiO2, the precursors were dissolved in a mix of methanol, glacial acetic acid, and sulfuric acid; the disolution was stirried and heated at 65 °C and kept under a reflux system, resulting in a white precipitate. This precipitate was centrifuged, decanted, dried at 200 °C for 2 h, and finally calcined in air at 650 °C for 6 h. For depositing the TiO2 coatings, a paste prepared from TiO2 powders, deionized water and lactic was used. Afterwards, the coatings were dried at 45 °C for 2 h, and finally thermally treated at 400 and 450 °C for 3 h. The structure and morphology of the TiO2 powders were analyzed by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM), respectively, whereas the TiO2 coatings were characterized by profilometry and Atomic Force Microscopy (AFM). The gas sensing response of the coatings was tested in both, C3H8 and CO, at different operating temperatures and gas concentrations. The sensitivity results were significant to both gases, and it was confirmed the potential application of TiO2 coatings deposited by the Doctor Blade method as gas sensors.