• 한국세라믹학회지
• /
• 제53권6호
• /
• pp.665-669
• /
• 2016

$TiO_2/BiVO_4$ layered films were prepared by sol-gel and spin coating methods. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Uv-vis spectroscopy were used to investigate the crystal structure, morphology and ultraviolet-visible absorption of the $TiO_2/BiVO_4$ films. The photocatalytic activity of the prepared films was inspected according to the degradation of methylene blue. The results show that the prepared films present a net chain structure; the absorption band edge had obvious red shift. The degradation of the methylene blue solution was about 80% after 300 mins using $TiO_2/BiVO_4$ layered films under visible light, which was stronger than when using only pure $TiO_2$ film and $BiVO_4$ film.

• 한국재료학회지
• /
• 제12권5호
• /
• pp.353-358
• /
• 2002

The microstructure and growth behaviors of anodic oxide layers on titanium were investigated. $TiO_2$ oxide films were prepared by anodizing at constant voltages of 180 and 200V in sulfuric acid electrolyte. The anodic $TiO_2$ layer formed at 200V showed a cell structure with more irregular pore shapes around the interface between the anodic oxide layer and the substrate titanium compared with that formed at 180V. Irregular shape of pores at the initial stage of anodization seemed to be attributed to spark discharge phenomena which heavily occurred during increasing voltages. The thickness of the anodic oxide film increased linearly at a rate of $1.9{\times}10^{ -1}\mu\textrm{m}$/min. The oxide layers formed at 180 and 200V were composed mainly of anatase structure, and the anodizing process could be suggested as one of fabrication methods of photocatalytic $TiO_2$.

• Environmental Engineering Research
• /
• 제19권3호
• /
• pp.215-221
• /
• 2014

Nano-sized $TiO_2$ particles were produced by a premixed flame aerosol reactor, and they were immobilized on a mesh-type substrate in form of particulate film. The reactor made it possible maintaining the original particulate characteristics determined in the flame synthetic process. The particulate morphology and crystalline phase were not changed until the particulate were finally coated on the substrate, which resulted in the better performance of the photocatalytic conversion of the volatile organic compounds (VOCs) in the ultraviolet $(UV)-TiO_2$ system. In the flame aerosol reactor, the various specific surface areas and the anatase weight fractions of the synthesized particles were obtained by manipulating the parameters in the combustion process. The performance of the $TiO_2$ particulate films was evaluated for the destruction of the VOCs under the various UV irradiation conditions. The decomposition rates of benzene and formaldehyde under the irradiation of UV-C of 254 nm in wavelength were evaluated to check the performance of $TiO_2$ film layer to be applied in air quality control system.

• 한국재료학회지
• /
• 제28권11호
• /
• pp.620-626
• /
• 2018

Highly self-cleaning thin films of $TiO_2-SiO_2$ co-doped with Ag and F are prepared by the sol-gel method. The asprepared thin films consist of bottom $SiO_2$ and top $TiO_2$ layers which are modified by doping with F, Ag and F-Ag elements. XRD analysis confirms that the prepared thin film is a crystalline anatase phase. UV-vis spectra show that the light absorption of $Ag-F-TiO_2/SiO_2$ thin films is tuned in the visible region. The self-cleaning properties of the prepared films are evaluated by a water contact angle measurement under UV light irradiation. The photocatalytic performances of the thin films are studied using methylene blue dye under both UV and visible light irradiation. The $Ag-F-TiO_2/SiO_2$ thin films exhibit higher photocatalytic activity under both UV and visible light compared with other samples of pure $TiO_2$, Ag-doped $TiO_2$, and F-doped $TiO_2$ films.

• 한국에너지공학회:학술대회논문집
• /
• 한국에너지공학회 1995년도 춘계학술발표회 초록집
• /
• pp.60-68
• /
• 1995

This work wes performed to investigate the photocatalytic decolorization of waste water from textile industries. Methyl orange was used as a target dye with suspended Hombikat TiO$_2$ photocatalyst with a recirculating annular photoreactor. 1 wt % Pt-doped Hombikat thin film tubular reactor with parabolic reflector also wes usedin this experiment. The pH effect and flow rate effect on photobleaching of 0.012 g/l methyl orange solution, AtpH=3 Colour of methyl orange was completely bleached in 30 min with a 20 W UV lamp.

• 한국표면공학회지
• /
• 제32권3호
• /
• pp.336-339
• /
• 1999

Photo-excited $TiO_2$ surface has a strong ability to induce various chemical reactions. Our study concentrates mainly on the utilisation of light energy to induce reactive radicals for environmental protection application. For instance, we have successfully used TiO$_2$ to break down foul smelling substances in air. In order to retain and separate the $TiO_2$ catalyst from the reactants and products, $TiO_2$ was immobilised by fixing onto various substrates. $TiO_2$ catalyst coated onto glass, wall paper and painted panel was found to show significant deodorising effect. The deodorising effect continues as long as$TiO_2$ is exposed to light irradiation.

• 한국가시화정보학회지
• /
• 제20권3호
• /
• pp.42-48
• /
• 2022

The shortage of available freshwater is a major global issue worldwide and an increasing demand for clean water requires efficient water purification strategies. Here we describe a method to drastically increase the efficiency of a microreactor for photocatalytic water purification. To find out how the shape of the catalyst affects water purification, nanostructured catalysts of different structures, such as dense film, nanorod, and nanohelix, are prepared and their water purification characteristics are analyzed. Compared to the flat catalyst, the nanostructured catalyst showed a distinct ability in its pollutant degradation, but the detailed structural variation does not significantly affect the water purification. To further increase efficiency, we apply a micromixer to nanorod-based microreactor, which allows even enhanced mass transfer. This enables the solution of the water purification problem and greatly contributes to the industries where the efficiency of photocatalytic activity has attracted extensive interest.

• 한국재료학회지
• /
• 제11권1호
• /
• pp.61-66
• /
• 2001

양극산화법을 이용하여 광촉매 특성을 나타내는 $TiO_2$ 피막을 제조하고 염료의 분해반응을 통하여 광분해 효율을 조사하였다 양극산화법에 의해 제조된 산화피막은 모두 광촉매 분해특성이 있었으며 양극산화의 조건에 따라서 $TiO_2$ 피막의 성장거동과 피막 형태에 차이가 나타났다. 황산용액에서 양극산화된 $TiO_2$ 피막은 불규칙적 인 입자모양으로 anatase와 rutile이 혼합된 조직이었으며, 인산이 첨가된 혼합용액에서 형성된 $TiO_2$는 anatase로 셀 모양의 피막형태로 생성되었다. 광촉매 특성에 적합한 양극산화의 인가 전압은 180V인 것으로 나타났다.

• Bulletin of the Korean Chemical Society
• /
• 제31권10호
• /
• pp.2849-2853
• /
• 2010

A method to improve the photocatalytic activity of titanium dioxide by modification with a sensitizer and a metal oxide is proposed. To achieve this goal, we used metal oxides as dopants. In particular, $CaWO_4$ and $Gd_2O_2S$:Tb were used because their 2.6 eV and 2.2 eV band gap energy and optical properties have a large positive effect on photocatalysis. The improvement in the photocatalytic activity of $TiO_2$ modified with $Gd_2O_2S$:Tb under ultraviolet light irradiation is described in a previous study. The present work focuses on the sensitization of metal oxide-modified $TiO_2$. Having observed the ultraviolet-visible absorption spectra of 3,4,9,10-Perylenetetracarboxylic diimide in the wide visible-light region from 400 nm to 650 nm and the broad peaks in its photoluminescence spectra at 695 nm and 717 nm, we decided to use this perylene dye to sensitize modified $TiO_2$ to enhance its activity as a visible-light harvesting photocatalyst. We also explored the positive effects thin-film surface changes stemming from ultraviolet pre-treatment have on photocatalytic activity. Finally, we subjected several metal oxide-modified $TiO_2$ products sensitized by the perylene dye to ultraviolet pre-treatment, obtaining the most active photocatalysts.

• 한국수소및신에너지학회논문집
• /
• 제21권5호
• /
• pp.375-382
• /
• 2010

A layered perovskite photocatalysts, $SrBi_2Nb_2O_9$ (SBN), was synthesized by the conventional solid-state reaction method and characterized by X-ray diffraction (XRD) and UV-visble spectrophotometry. The results showed that the structure of $SrBi_2Nb_2O_9$ is orthorhombic. Diffuse reflectance spectra for calcined and attrition-milled SBN showed the main absorption edges were less 400 nm, that is ultraviolet region. SBN under micron-sized powder was deposited on the $Al_2O_3$ by room temperature powder spray in vacuum process, so called aerosol deposition (AD), and nano-grained $SrBi_2Nb_2O_9$ photocatalytic thick film was fabricated. AD-deposited SBN thick films were characterized by XRD, scanning electron microscopy (SEM) and UV-visable spectrophotometry, Moreover, it was found that several nano-sized SBN film by AD process can improve the photocatalytic activity under visable reflectance.