Papers by Keyword: ZnO-TiO₂

Abstract: Zinc oxide-titanium dioxide (ZnO-TiO₂) have been successfully synthesized by hydrothermal method. ZnO-TiO₂ nanocomposite were prepared at different molar ratio 100:0, 100:0, 30:70, 50:50 and 70:30. The objective of this research is to determine the effect of molar ratios on the structural and optical properties of ZnO-TiO₂ nanocomposite. The samples were analyzed using X-ray diffraction (XRD) analysis, Field-emission scanning electron microscopy (FESEM) and UV-Vis spectroscopy. Based on the XRD results, it is revealed that ZnO-TiO₂ nanocomposite consists of hexagonal wurtzite structure of ZnO and mixed of anatase/ rutile phase of TiO₂. FESEM images showed ZnO in rod-like structure while TiO₂ is formed in nanoparticle. ZnO-TiO₂ composite is formed combination of rod-like and nanoparticles. UV-Vis spectra showed that all samples exhibited good absorption towards UV region. The calculated energy band gaps of ZnO-TiO₂ composite are 2.92 eV which is slightly smaller compared to bulk ZnO and TiO₂. The tuning energy band gaps of ZnO-TiO₂ composite samples is a good indicator for use in catalytic activities.

Abstract: Ho³⁺/Yb³⁺ co-doped ZnO-TiO₂ composite system were synthesized by powder-solution mixing method and their upconversion (UC) luminescence characteristics were investigated under the 980 nm laser excitation. The effect of various ZnO/TiO₂ mixing ratios, and Ho³⁺ and Yb³⁺ concentrations were also studied. The XRD patterns showed that the product fired at 1300 °C consisted of Zn₂TiO₄, TiO₂, RE₂Ti₂O₇, and RE₂TiO₅ (RE = Ho³⁺ and/or Yb³⁺) phases. The green emission centered at 538 nm wavelength was detected as the strongest emission intensity which it was in accordance with the ⁵F_4, ⁵S₂ → ⁵I₈ transition of Ho³⁺ ion. The emission intensity of the product changed by varying ZnO/TiO₂ mixing ratios, and Ho³⁺ and Yb³⁺ concentrations. Brightest UC emission was observed in the sample of 1ZnO:1TiO₂ (in mole) doped with 0.03 mol% Ho³⁺, 9 mol% Yb³⁺ fired at 1300 °C for 1 h. Besides, the dependence of the UC emission intensity on the excitation power indicated that the two-photon process was responsible for this UC system.

Abstract: Prepared and heat-treated sol-gel ZnO-TiO₂ coatings onto microscope glass slides were characterised by atomic force microscopy (AFM), scanning electron microscopy (SEM), as well as absorption spectra of light has been obtained. Thermally treated xerogels were characterised by X-ray diffraction (XRD). As well as their photocatalytic activity using methyl orange (MO) and observing the colour changes over the time in visible light (VIS) and ultra violet (UV) light has been determined. The influence of ZnO concentration on morphology, photocatalytic activity and antibacterial properties of coatings was analysed. The growth of S. epidermidis on the surface of the samples was inhibited due to photocatalytic properties of coatings.

Abstract: The sol-gel method is adopted in this study to prepare the TiO₂-composite semiconductor materials doped with ZnO, whose crystal structures are characterized by way of X-ray diffraction and Transmission Electron Microscopy (TEM). It is concluded that the optimal doping amounts of Zn and lanthanum and the calcination temperature are respectively 3%, 0.3% and 500°C. Mixed with water, the photocatalytic oxidation effects of reactive brilliant blue X-BR, taken as the degradation target, was investigated in this study. When the doping amount of lanthanum is 0.3%, the chroma removal rate of the reactive brilliant blue X-BR by lanthanum-modified ZnO-TiO₂ can reach 97.3%. The conditions for optimal decolorization rate are: under ultraviolet light for 2h, using the 100mg / L reactive dyes, controlling pH at about 1 and the chloride concentration at 1mol / L.

Abstract: This experiment aims to prepare the Zn^{2 +}-doped TiO₂ composite semiconductor materials by the sol-gel method and to characterize their crystal structures by X-ray diffraction and electron microscopy (SEM) scanning. The degradation target in this experiment is the pharmaceutical wastewater of a certain Chinese patent medicine, whose COD is as high as 300,000 mg/L and chroma is above 500 degrees. When the doping ratio of ZnO is 8%, the pharmaceutical wastewaters COD and chroma removal rates for 2hs degradation respectively reach 72.5% and 33.8%. The doping of Ce⁴⁺ or La³⁺ can improve the catalytic activity of ZnO-TiO₂. The cerium doped in can improve ZnO-TiO₂s catalytic property within 7%, and when the doping ratio of lanthanum is 0.4%, the chroma removal rate of the pharmaceutical wastewater reaches 65%, 31.2% more than that of the pure ZnO-TiO₂.

Abstract: This research aims to treat pharmaceutical wastewater with the ZnO-TiO₂composite material prepared by the sol-gel method. It examines and analyzes the causes and effects of ZnO‘s doping ratio, calcination temperature calcination time and irradiation time on ZnO-TiO₂ composite photocatalyst material’s degradation of pharmaceutical wastewater. Both the undoped TiO₂ test and the blank test are done for its reference and contrast.

Abstract: Using titanyl sulfate and zinc sulfate and others as the main resources, we adopted separately sluggish precipitation method and co-precipitation method to prepare pure TiO₂ nano-powder and ZnO-TiO₂ nano-composite photo-catalytic materials. The authors used X-Ray Diffraction (XRD) to research crystal types of the TiO₂ nano-powder and ZnO-TiO₂ nano-composite photo-catalytic materials, and conducted experiments of photo-catalytic performance and light absorption performance of the samples that were made. The experiment results showed that the prepared TiO₂-ZnO nano-composite photo-catalytic materials are relatively ideal. The paper used visible light as the light source to realize the effective degradation of the organic matters.

Abstract: The effects of CuO-MoO3 addition on the sintering behavior and microwave dielectric properties of ZnO-TiO2 ceramics were investigated. ZnO-TiO2 ceramics were prepared with conventional solid-state method and sintered at temperatures from 850 to 1050 °C. The sintering temperature of ZnO-TiO2 ceramics with CuO-MoO3 addition could be effectively reduced to 950 °C due to the liquid phase effects resulting from the additives. A proper amount of CuO-MoO3 addition could effectively improve the densification and microwave dielectric properties of ZnO-TiO2 ceramics. ZnO-TiO2 ceramics with 3 wt% addition sintered at 950 °C for 4 h exhibited better microwave dielectric properties as follows: εr of 26.8, a Q×f value of 16780 GHz at 5.42 GHz, and a τ f value of +34.7 ppm/°C.