Photocatalytical Decomposition of Contaminants οn Thin Film Gas Sensors

Gas sensing materials have been prepared in a form of $TiO_{2}-SnO_{2}$ thin films by rf reactive sputtering from $Ti:SnO_{2}$ and $Sn:TiO_{2}$ targets. Material studies have been performed by scanning electron microscopy, atomic force microscopy, X-ray diffraction at grazing incidence, Mössbauer spectroscopy, X-ray photoelectron spectroscopy and optical spectrophotometry. Dynamic gas sensing responses have been recorded as reproducible changes in the electrical resistance upon introduction of hydrogen at a partial pressure of 100-6000 ppm over a wide temperature range 473-873 K. Contamination experiments have been carried out with the motor oil (40 vol.% solution in $CCl_{4}$) in order to study the effect of UV light illumination on the gas sensor response. Optical spectroscopy has been applied to monitor the photodecomposition of the test compound, bromothymol blue. The Electronic Nose, ALPHA MOS FOX 4000 has been used in order to differentiate between different groups of motor oil vapors.