Papers by Keyword: Sol-Gel Method

Abstract: Butyl acetate titanate as precursors, no water ethanol as solvent, pure TiO2 and different doping ratio of F/TiO2 photocatalysts were prepared through sol-gel method; And F doping amount on photocatalytic activity of TiO2 influences were analysed systematically through uv-vis spectrophotometer, infrared spectrometer, etc. Experimental results show that photocatalytic activity of TiO2 is better when the mole ratio of F is between 10% and 20%; When F doping amount is 20%, catalyst amount is 25g, the photocatalytic degradation rate of F/TiO2 can reach 85.74% in10%wt methylene blue solution under 250W high-voltage mercury lamp illumination after 2 hours and the area of illumination 6.94×10-3m2. In the same way, the photocatalytic degradation rate of pure TiO2 is just 35.39 %. It proves that F/TiO2 catalyst of doping amount 20% presents the best photocatalytic activity.

Abstract: Aluminum titanate (Al₂TiO₅) film was prepared via sol-gel method at low temperature, using ethyl acetoacetate and anhydrous citric acid as compound chelating agent, tetrabutyl titanate (Ti (OC₄H₉)₄) and aluminum chloride (AlCl₃^.6H₂O) as precursors, ethanol as solvent. The phase transformation of Al₂TiO₅ xerogel during heat treatment, the effect of different chelating agents on the synthesis of Al₂TiO₅, and the phase composition and morphology of film were investigated by means of differential thermal and thermo gravimetric analysis (DTA-TG), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR) and field-emission scanning electron microscopy (FE-SEM). The results demonstrate that Al₂TiO₅ can be synthesized at 750 °C by using compound chelating agent, rather than single chelating agent. Compound chelating agent contributes to the formation of Al-O-Ti heterogeneous bond, which is the key to preparing Al₂TiO₅ at low temperature. High quality Al₂TiO₅ film could be coated on the SiC substract at 750°C.

Abstract: Cu-N co-doped TiO₂ powder was prepared by sol-gel method. The Powder was characterized by X-ray diffraction (XRD) and UV-Visible absorbance spectroscopy (UV-Vis). The X-ray results indicated that Cu-N co-doped has no effect on its anatase type. The UV-Vis results show that the absorb threshold has extend to visible-light, the absorbility of co-doped TiO₂ is higher than that of pure TiO₂, and the Photocatalytic activity has been increased.

Abstract: Butyl titanate as titanium source, anhydrous ethanol as solvent, glacial acetic acid as inhibitor, La-WO₃/TiO₂, La/TiO₂, WO₃/TiO₂ and pure TiO₂ photocatalysts were prepared through sol-gel method; At the same time, both of which were characterized by infrared spectrometer and uv-vis spectrophotometer; With methyl orange as simulated target degradation material, heat treatment temperature、different dopants, etc. on photocatalytic performance influences of TiO₂ were studied by spectrophotometer. Experimental results show that doping can improve obviously the photocatalytic activity of TiO₂. When calcination temperature is 500 ℃, dosage of catalyst is 0.25 g, pH is 1, and methyl orange concentration is 10 mg/L, La-WO₃/TiO₂ photocatalytic effect is best, and degradation rate is 46.18%.

Abstract: Summarizd the methods of oxide coated on the surface of carbon nanotubes. Using carbon nanotubes (CNTs) as template, TiO₂/CNTs nanocomposite was prepared by a sol-gel method. Urea as a promoter, obtained by the slow hydrolysis of tetrabutyl titanate Ti (OH)₄ precursor is deposited on the carbon nanotubes, is further dehydrated to form TiO₂. Its structure was characterized by X-ray energy spectroscopy (EDS) and scanning electron microscopy (SEM), and obtain uniform coating of TiO₂/CNTs composites

Abstract: Zinc oxide (ZnO) thin films were prepared by sol-gel spin coating technique, which were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), NKD thin film analysis system and fluorescence spectrophotometer. The results show that ZnO thin films with the each layer thickness of 80 nm present obvious c-axis orientation. With the increase of coating layers, the c-axis orientation characteristic weakens. The reason is considered that the growth mode of ZnO thin films transforms from layer growth to island growth. For the ZnO thin film with 4 layers, it has a compact surface and a uniform particle size of approximately 50 nm, and the photoluminescence (PL) spectrum primarily consists of two PL emission bands, one is a strong and narrow ultraviolet (UV) emission band, another is a weak and broad luminescence emission band from 400 nm to 650 nm. The average transmittance in the visible range is beyond 90%. A optical band gap of 3.26 eV, slightly less than the intrinsic band gap width of 3.37 eV, is obtained by Tauc plotting method. The defects, such as Zn or O vacancies, grain boundaries, are considered to be the main factors causing this situation.

Abstract: Solvolytic sol-gel synthesis was applied for the low temperature production of photoelectrode for dye-sensitized solar cell (DSSC). In this study, commercial TiO₂ standard (Degussa P25) was used as the main component in the preparation of photoelectrode film. Addition of TiO₂ gel prepared from a solvolytic sol-gel method reduced cracking in the dry film while still maintains porosity. Further modification by simply adding hydrofluoric acid (HF) and ammonia (NH₃) increase porosity and improve interconnection between fluorine doped tin oxide (FTO) layer on the substrate and the coated TiO₂ layer even under low temperature baking condition (<150°C). The modified TiO₂ electrode showed significantly better electrical and electrochemical properties. Furthermore, the DSSC cell with modified TiO₂ film also showed higher cell efficiency when compared with the controlled cell that used only Degussa P25.

Abstract: Magnetite (Fe₃O₄) nanoparticles were successfully synthesized by the sol-gel method from ferric nitrate-EG (EG=ethylene glycol) gel. The precursors were calcined in argon under an atmospheric pressure at the temperatures varied from 400°C to 500°C. The synthesized magnetic nanoparticles were characterized by X-ray diffractrometer (XRD), field emission scanning electron microscope (FE-SEM) and vibrating sample magnetometer (VSM). The XRD patterns of powder calcined temperature at 400^๐C showed clearer Fe₃O₄ phase than those calcined at other temperatures. The particle size and morphology of magnetic nanoparticles were studied using FE-SEM. The FE-SEM images showed that the particle sizes varied from 30-108 nm. The particle sizes increased with the increase of calcination temperature. VSM measurements indicated that the Fe₃O₄ nanoparticles were soft ferrite with the maximum magnetization (M_m) and coercivity (H_c) of 35 emu/g and 17 Oe, respectively.

Abstract: Fluorine-doped tin dioxide (FTO) nanocrystals were prepared with sol–gel method using SnCl₄·5H₂O and NH₄F as precursor material. The FTO was characterized with X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Differential Thermal Analysis and Thermal Grativity (DTA-TG) and Infrared Radiation (IR) respectively. The electrical property was measured with Hall Effect Sensor. The result of XRD and SEM shows that FTO nanocrystal size is about 20 nm and the dimension of the grain is about 300 nm. IR spectrum analysis proves fluorine doping. The crystal phase transformation was discussed with DTA-TG curve. When the sintering temperature is 450°C, the sintering time is 60 min, and the molar ratio of F to Sn is 2:10, the sheet resistance of FTO film is 107Ω/□.

Abstract: Nano-sized LiNi0.5Mn1.5O4 spines is prepared by a sol-gel reaction at 800 °C in air. Scanning electron microscopic (SEM) image indicates that LiNi0.5Mn1.5O4 has cubic spinel structure with small and homogeneous particles (about 300 nm). Electrochemical test shows that the prepared LiNi0.5Mn1.5O4 delivers up to 125 mAh g− 1at 0.2 C, and the capacity retains 110 mAh g− 1 at 0.5 C after 50 cycles.