Papers by Keyword: Nanocrystalline TiO₂

Abstract: In order to extend light response of TiO₂ into the visible region and enhance its photocatalytic activity, V and W surface codoped nanocrytalline TiO₂ film was synthesized by the sol-gel method. Tetrabutyl titanate (Ti (OC₄H₉)₄) was chosen as the precursor, and ammonium metavanadate or ammonium tungstate was chosen as vanadium or tungsten source. The high-resolution field emission scanning electron microscopy (FE-SEM) results revealed that the film was composed of uniform round-like nanoparticles with size smaller than 6 nm. The photocatalytic activities of TiO₂ films were investigated by degradation of organic dyes in aqueous solutions. V and W codoped TiO₂ film exhibited excellent photocatalytic activity compared to undoped TiO₂ film or single doped TiO₂ film. The improvement mechanism by V and W codoping was also discussed. Keywords: Nanocrystalline TiO₂; Composte films; Photocatalytic activity

Abstract: Nanocrystalline TiO₂ has been synthesized through non-aqueous sol-gel using acetic acid (HOAc) and hydrochloric acid (HCl) as a catalyst. Titanium isopropoxide (TTIP) as precursor was prepared by reaction between TiCl₄ with isopropyl alcohol (IPA) in concentration of 0.3 M. The sol-gel process employed at around 60°C using tert-butanol as solvent and HOAc was added as ligand to stabilize the reaction. Controlled hydrolysis and condensation reactions were achieved through in-taking of water molecules released from the esterification reaction of HOAc with tert-butanol. In this paper, the influence of acidic catalyst was described at the volume ratio of HOAc:HCl are 0:2 ; 1:1 and 2:0. The crystallinity and crystal phase of the samples were characterized by X-ray Diffraction and nanocrystalline TiO₂ with anatase phase was resulted. The morphology of the TiO₂ powder was analyzed by Scanning Electron Microscopy. Pore size and the BET surface area were determined by Brunauer-Emmett-Teller (BET) analysis. Nanocrystalline TiO₂ produced was applied for photoelectrode of dye-sensitized solar cell. The optical properties of the TiO₂ photoelectrodes were measured using by UV-Vis Spectrophotometer. The performance of the cell was measured using a solar simulator with light at an intensity of 50 mW/cm² generated by a xenon lamp. The best efficiency of 0.5% was achieved for active area of 0.48 cm².

Abstract: The new technique for the TiO₂ photocatalyst manufacturing with titanium tetrachloride alcoholic solution using was revealed. The ammonium titanate precursor was precipitated by double-jet method with TiCl₄ alcoholic and ammonium aquatic solutions using. The TiO₂ nanopowders were prepared by precursors calcinations at 400, 500, 600, 700 and 800°C. The photocatalytic activity determination was made by the way of dye photodegradation technique (methyl orange). The difference in adsorption ability of TiO₂ dispersion reference to organic dyes was found. The conditions for the synthesis of TiO₂ anatase effective photocatalyst synthesis were revealed.

Abstract: Nanocrystalline and flower like structured TiO2 thin films are prepared by sol-gel spin coating method. The prepared films are annealed at 450°C. Natural dyes are prepared from delonix regia flower and eugenia Jambolana fruit. The prepared natural dyes were sensitized into both nanocrystalline and flower like structured TiO2 thin films. The prepared solar cell was characterized by SEM, Uv-Vis spectroscopy and J-V characteristics. Conversion of solar light into electricity was successfully accomplished with both natural dye based solar cells. The best solar energy conversion efficiency (ƞ= 0.2%) was obtained for eugenia Jambolana dye sensitized flower like structured TiO2 thin film solar cell.

Abstract: Solid state polymer electrolyte blend of polyethylene oxide, chitosan, ammonium iodide, and iodine crystals has been prepared by solution cast technique. The highest ionic conductivity of the polymer electrolyte was 1.18 × 10−5 S cm−1 at room temperature. Addition of chitosan to the electrolyte has improved its mechanical properties. A photovoltaic junction with configuration ITO/TiO2-solid state polymer blend electrolyte/ITO has been constructed. The open circuit voltage Voc, short circuit current density Jsc, and fill factor FF% obtained from the photovoltaic system under white light illumination of 100W Tungsten lamp are 320-350 mV, 0.59-2.5μAcm-2 and 42%-59% respectively.

Abstract: We are presenting our results based on unsymmetrical zinc phthalocyanine by adopting ‘push-pull’ concept for the nanocrystalline dye-sensitized solar cells. Using this sensitizer in combination with nonvolatile organic-solvent-based electrolytes, we obtained a photovoltaic efficiency of 1.52% under standard global AM 1.5 sunlight and compared the results with volatile organic-solvent based electrolyte. These devices exhibit admirable stability when subjected to continuous thermal stress at 60 oC for 1000 h. The sensitizer is thermally stable up to 150 oC and can be useful for roof top applications.