Papers by Keyword: Photocatalytic

Abstract: This study targets the development of a polishing technique that uses a photocatalyst and a fluorescent substance excited by an ultraviolet ray. Nickel (hereafter referred to as Ni) was polished chemically and mechanically at the micrometer level under ultraviolet-ray irradiation. Measurements clarified that TiO2 of 0.1-μm grain size, at which size the excitation by the ultraviolet ray was less influential, mechanically polished the Ni. Cathilon (a luminous dye) chemically polishes Ni. The corrosion of the Ni surface became large under ultraviolet-ray excitation. A flat surface was attained on the Ni by chemical and mechanical polishing using both the TiO2 and cathilon, when was irradiated by an ultraviolet ray.

Abstract: This study investigated the effect of surface roughness on a coating of TiO2 submicron powders that had been applied on a stainless steel mesh using electrophoretic deposition (EPD). Roughness was provided to the surface of EPD coating using UV pre-illumination to the suspension prepared by isopropyl alcohol and commercial TiO2 powder. The Ra value was increased around 20% by this treatment. The rough coating provided a higher photocatalytic decomposition rate of 1,4-dioxane in water than a smooth coating obtained from the suspension without UV pre-illumination. That increase is attributable to the increase of the reaction field on the coating surface.

Abstract: TiO2 shows a high efficiency in Photocatalysis, however, the recycling of TiO2 is difficult, composite coating is prepared by simultaneous elecroless deposition of NiP and TiO2 on substrates, surface topography and hardness of composite coating are investigated by metalloscope, SEM, EDS and Vickers microhardness; The relation between absorbence of methyl orange and time is researched by 723# spectrophotometer. The results show when TiO2 content in bath is 4g/L, plating speed is most fast and amount to 12.2μm/h, the photocatalytic effect is best. by comparing the microhardness of heat-treated compound coating and the Ni-P alloy coating, the maximum microhardness of the former appears in 500°C and achieves HV1180, and the latter appears in 400 °C and achieves HV950.

Abstract: To obtain porous and thick TiO2 film, the precursor sol was prepared by hydrolysis of Ti isopropoxide and then complexed with trehalose dihydrate. The porous TiO2 film was fabricated by dip-coating technique on quartz glass substrates using this sol. The TiO2 films were calcined at 500-700 °C. The photocatalytic activity of the films was evaluated by examining decomposition of methylene blue in aqueous solution under UV light irradiation. The TiO2 film prepared from the sol with trehalose was more active than TiO2 film prepared from the sol without trehalose. The trehalose addition to the dip-coating solution was effective in improving the photocatalytic activity of the TiO2 film.

Abstract: Visible-light responsible Mn-N-codoped TiO2 nanocrystal photocatalysts were synthesized for the first time by a simple hydrothermal synthesis method. X-ray powder diffraction (XRD) measurement indicated that all of the photocatalysts have an anatase crystallite structure and the increase of the doping concentration had less effect on the structure and particle size. Comparing to N-doped TiO2, a shift of the absorption edge of Mn-N-codoped TiO2 to a lower energy and a stronger absorption in the visible light region were observed. The Mn-N-codoped TiO2 showed a higher photocatalytic reactivity than undoped TiO2 and N-doped TiO2 for the photodegradation of rhodamine B (RhB) under visible light irradiation. The doping concentration had an optimal value, according to the highest photocatalytic activity. This suggested that Mn and N codoping has important effects on the improvement of visible-light responsible photocatalytic activity.

Abstract: Nitrogen doped titania was coupled with the commercial titania nanoparticles by mechanical milling in liquid medium. When small amount of nitrogen doped titania was added into the commercial titania, higher intensity and longer lifetime of 1O2 was observed, and the photocatalytic activity was efficiently improved. The TiO2-xNy acts as the acceptor of photoinduced holes. The recombination of the electron-hole was effectively depressed by the heterogeneous electron transfer. This could be an effective way to obtain high active photocatalyst.

Abstract: Fluidized Bed Chemical Vapor Deposition (FB-CVD) method offers advantages over conventional Chemical Vapor Deposition method in coating three dimensional objects. In addition, catalysts prepared by FB-CVD method often show improved physicochemical properties. Thus, FB-CVD seems a useful method for coating TiO2 onto small beads, in view of their photocatalytic application in aqueous environment, for example. In this work, we produced TiO2 coated beads (1~2mm in diameter) of alumina, silica-gel, and glass in ~35nm thickness using FB-CVD method, and examined photocatalytic performance of TiO2 coated beads in the photocatalytic decomposition reaction of methylene blue solution. Based on the combined results of the decomposition reaction kinetics of methylene blue and FE-SEM images of the surface morphology of TiO2 coated beads, we were able to account for the photocatalytic performance with respect to characteristic features detected in the surface morphology.

Abstract: The influence of the titania photocatalyst nano-particles to the skin is to be doubted. We studied the influence of different titania photocatalyst nanoparticles shape to the artificial skin like the human body under the UV light irradiation conditions. The decomposition degree of the artificial skin was evaluated from the monitoring of the amount of carbon dioxide generated from them by the titania photocatalyst nanoparticle activity. When spreading their titania nanoparticles on the skin sample, the carbon dioxide generated from the skin was not detected in the apatite coating titania nano-particle sample through was detected the sample coating no apatite. The result was considered not to have existed the influence on the skin samples because the titania nano-particle was not to touch the skin sample directly.

Abstract: F-doped TiO2 has exhibited superior photocatalytic activity. However, its electronic structures and photocatalysis mechanism are still unclear. In the present work, the structural optimization and electronic structure of F-doped anatase TiO2 have been investigated by means of the first-principles pseudopotential total energy method. It has been demonstrated that F doping would modify the valence band at the lower energy direction in the F-doped TiO2. Calculation results confirm that doping of fluorine would not shift the absorption edge into the visible light region. Instead, we attributed its photocatalytic activity to the enhancement of the oxidative power of F-doped TiO2.

Abstract: Developing new semiconductor materials with improved photocatalytic activity is a promising technology for the remedy of environmental pollution. Here we report on the synthesis of Yb containing TiO2 nanoparticles and their catalytic activity under visible light. Highly monodispersed, spherical TiO2 and TiO2 :Yb nanoparticles of 27- 40 nm size range were prepared through controlled hydrolysis of titanium tetrabutoxide (TTB) and characterized by X-ray diffraction (XRD), energy dispersion spectroscopy (EDS), high-resolution transmission electron microscopy (HRTEM), high angle annular dark field (HAADF), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS) techniques. Average size of the nanoparticles was found to decrease with the increase of Yb doping concentration. The photocatalytic activity of Yb doped TiO2 was evaluated by measuring the degradation rates of methylene blue (MB) under UV and visible lights. Doping with ytterbium ions enhanced significantly the photocatalytic activity of TiO2 nanoparticles for MB oxidation under visible light.