Papers by Keyword: Photodeposition

Abstract: Titanium dioxide (TiO₂) nanotubes with a highly ordered structure were grown by a self-organized anodization process. The photodeposition process was used to improve the visible light response of titanium dioxide (TiO₂) nanotubes. The irradiation was carried out with 500 W halogen lamp for 1, 5, 15, 30 and 60 min in the mixed ethanol solution of antimony trisulfide (Sb₂S₃). The obtained samples were annealed at 250 °C for 30 min. The morphology of the fabricated sample was characterized by a field emission scanning electron microscope (FE-SEM). The phase of samples was determined by X- ray diffractometer (XRD). The weight percentages of a component in the sample were measured by X-ray fluorescence spectrometry (XRF). UV-Vis diffuse reflectance spectra (DRS) of the samples were recorded. All titanium dioxide (TiO₂) nanotube samples prepared by anodization process were anatase phase. All composite titanium dioxide (TiO₂) nanotube /Sb₂S₃ samples were a crystalline phase. The percentage of Sb and S increase with increasing of photodeposition’s time. The increasing photodeposition of antimony trisulfide (Sb₂S₃) on titanium (TiO₂) nanotubes from 1 to 60 min lead to increasing of photoabsorption property of the material in the visible region.

Abstract: Friction stir processing (FSP) has successfully evolved as a technique in fabricating surface composite. An alternative technique on fabrication of a SiC-reinforced Al6061 aluminum matrix composite (AMC) by stirring copper-coated SiC particles into matrix to form a reinforced zone was developed. Copper film was deposited onto the SiC particles by electroless plating and by photodeposition processes. The copper coating serves as an adhesion and diffusion layer to enhance the cohesion between the particles and the matrix. It is to expect that the strength of the AMC could be improved. The uniformity of particle distribution in the stir zone (SZ) was improved by adjusting the location of particle insert and by a double-pass stir. T5 post weld heat treatment (PWHT) was conducted to retrieve the hardness and the strength of the SZ to the strength level of the matrix. While the submicron-thick Cu-coating was partially separated from SiC particles after FSP, photodeposition Cu-coating less than 100 nm thick exhibited a better adhesion to the SiC particles. The EPMA analysis across the interface shows evidence of interdiffusion between copper and aluminum which implies an enhanced cohesion between the particles and matrix. After PWHT, while the SZ containing photodeposition Cu-coated SiC exhibited the highest hardness among different SZs, the SZ containing electroless Cu-coated SiC exhibited the highest strength. The possible mechanisms for the improvement of the hardness and strength were discussed. In summary, the purpose of fabricating a locally particulate-reinforced Al6061 AMC by stirring Cu-coated SiC particles into Al6061 matrix was achieved. Keywords:Friction stir processing (FSP), particulate reinforced AMC, electroless plating, photodeposition, copper-coated SiC particles

Abstract: We reported that titania ceramic coating loaded with palladium catalyst worked as an optical hydrogen gas sensor at room temperature. The palladium metal of this sensor worked as a catalyst not only for room-temperature operation but also for high selectivity to hydrogen gas. Precise control of metal/ceramic interface between the titania and the palladium was very important in order to improve the sensor performance such as sensitivity, response time, recovery time. Influence of a difference in palladium-catalyst loading method (photodeposition and sputtering) on the optical hydrogen gas sensing properties for the titania-based sensor was investigated. It was found that the catalytic loading process significantly affected the optical hydrogen characteristics of the titania-based coating.

Abstract: Palladium (Pd) nanoparticles were prepared on photocatalytic TiO2-coated glass substrate by a photodeposition process and the optical hydrogen sensing properties were examined at room temperature. The TiO2 coatings were prepared on a non-alkaline glass substrate by a sol-gel process and hot water treatment. Pd nanoparticles were deposited on the TiO2 film by photodeposition using UV light. The obtained Pd/TiO2 thin film showed remarkable optical transmittance response to hydrogen gas at room temperature. The normalized transmittance of the Pd/TiO2 thin film at a wavelength of 640 nm decreased to 0.9 on exposing the film to hydrogen gas for only 5 s. This transmittance decrease is considered to be due to a gaschromic effect of the TiO2 photocatalytic coating.

Abstract: Authors have successfully synthesized a new environmental catalysis which reacted with harmful formaldehyde in air at room temperature. Although manganese oxide is practically used for a major ingredient of formaldehyde removing materials, intermediates such as formate formed on the surface reduced the removal efficiency. Then, manganese oxide was photodeposited onto the surface of titanium dioxide particles which could decompose certain organic compounds with UV irradiation. It was confirmed that the complex oxide decomposed formaldehyde into carbon dioxide at room temperature. Moreover, UV irradiation enhanced the production of the carbon dioxide.