Study On Photo-Electrochemical Sensor Based On Oxide Modified Ti Electrode

Titanium dioxide is one kind of n-type semiconductor material. Nano-sizetitanium dioxide material not only has the general properties of the nanometermaterial but also has favorable photo-catalytic property so that it is in many people’sgood graces. The studies of the TiO2usually focused on photo-catalysis and solar cell.Ti meets the requirement for the substrate of the modified electrode because of itsgood stability，favorable conductivity and strong corrosion resistance. In this thesis,high purity Ti wire and Ti foil are chosen as substrate. Oxide layer was grown on theTi substrate by anodic oxidation method. This kind of modified electrode isresearched in photo-electrochemical field. Our research expended the use of TiO2nanometer materials. The thesis consists of4chapters. In the chapter1, thephoto-electric properties, species, preparation methods and applications of TiO2nano-materials are introduced.In the chapter2, C-doped TiO2film was prepared by anodized Ti wire in N,N-Dimethylformamide (DMF) at32V. The crystal form of the C-doped TiO2film wascharacterized by X-ray powder diffraction (XRD). Surface elements’ existing states ofthe C-doped TiO2film were characterizd by X-ray photoelectron spectroscopy (XPS).Band gap was decreased by C atoms in the TiO2crystal lattice so that the generationefficiency of hot electron was improved obviously. Luminol has good hot-electroninjected ECL at this kind of electrode. At this kind of ECL system, linear range ofLuminol was1.0×10-8mol/L-9.0×10-8mol/L, detection limit was2.0×10-9mol/L.In the chapter3, Ru(bpy)32+has hot-electron injected ECL at TiO2nanotubearray modified electode at-40V cathode pulse. The ECL of Ru(bpy)32+was thestrongest at anatase TiO2nanotube modified electrode. The morphology and structureof nanotube have influences on ECL of Ru(bpy)32+. The emission wavelength ofRu(bpy)32+was also been measured. The ECL mechanism of Ru(bpy)32+at TiO2nanotube modified electrode was Reduction-Oxidation type. The detection limit ofRu(bpy)32+was1.0×10-9mol/L at this kind of electrode.In the chapter4, the TiO2nanotube array modified electrode was prepared byanodizing Ti foil in the electrolyte solution containing F-and glycerol. The influencesof the crystal form and different sizes of the nanotube towards the pH responding sensitivity of the modified electrode have been researched. The results show thatTiO2/Ti electoed by natural oxidation has no pH response, pH response of anataseTiO2nanotube array modified electrode has deviated linear relationship, amorphousTiO2nanotube has good pH responding sensitivity. After being irradiated by UV, thesensitivity of the amorphous TiO2nanotube is improved to theory value (59.2mV/pH).This kind of electrode has good stability and reproducibility. It can be used to detectsome kinds of soft drinks. Electrodes’ surface morphology, crystal, existing state ofsurface elements were characterized to discuss possible mechanism of pH response. Itwas found that the pH responding sensitivity of the modified electrode inproved withthe increasing of surface hydroxyl groups and hydrophilicity.