Studies on Hydrogen Sensing by Anodized Nanoporous Titania Thin Film Using Soft Drink Electrolyte

Abstract

Nano-porous titanium dioxide (TiO2) 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 TiO2 thin film was annealed at 150ᴼC for 3 hours. The surface of the prepared TiO2 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 TiO2 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 200ᴼC) and in different hydrogen gas concentrations (1000 to 10000 ppm). Nanocrystalline and nano-porous TiO2 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 1500C. Brief mechanism behind the sensing performance has been also discussed.