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Studies on Hydrogen Sensing by Anodized Nanoporous Titania Thin Film Using Soft Drink Electrolyte
並列摘要
Nano-porous titanium dioxide (TiO_2) thin films were developed by UV assisted potentiostatic anodization of 99.7% pure titanium foil. The internationally popular soft drink 'Coca-Cola' was used as the electrolyte in this anodization process. Electrochemical oxidation and photoetching were carried out at room temperature and at 10 V potentiostatic bias without and with 400 W UV light illumination respectively. The prepared TiO_2 thin film was annealed at 150℃ for 3 hours. The surface of the prepared TiO_2 film was characterized with Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) to confirm the crystallinity, porous structure and surface roughness. The Optical study revealed a band gap of 3.898 eV. Hot probe method exhibited n-type conductivity of the electrochemically grown TiO_2 thin films. Palladium-Silver alloy (Pd-Ag) contacts were deposited laterally on the oxide surface as catalytic metal electrodes to fabricate a planar sensor configuration. The hydrogen sensor study was carried out at different temperatures (100 to 200℃) and in different hydrogen gas concentrations (1000 to 10000 ppm). Nanocrystalline and nano-porous TiO_2 sensor was promising to sense hydrogen in air ambient with relatively fast response and recovery times (e.g. ~2.9 s and ~75 s) at the optimum temperature of 150℃. Brief mechanism behind the sensing performance has been also discussed.