• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.1
• /
• pp.7-10
• /
• 2002

$TiO_2$ thin films were prepared by coating and subsequent pyrolysis processes using Titanium-naphthenate as a raw material. $TiO_2$ thin films were made by spin-coating technique on the glass substrates, and heat treated at 45$0^{\circ}C$, The transmittance, refractive index, crystallinity and surface morphology of the $TiO_2$ thin films were measured by UV/Vis spec trophotometer, x-ray diffractometer and scanning electron microscope. $TiO_2$thin films on the slide glass showed the trans mittance of 70-90% and refractive index of 2.6 at 420 nm. The results of XRD and SEM showed that the $TiO_2$ thin films exhibited the anatase phase and the thread-like surface morphology.

• Analytical Science and Technology
• /
• v.21 no.3
• /
• pp.229-236
• /
• 2008

$C/TiO_2$ composites were prepared with surface modified MWCNT sequentially after HCl treatment and TNB as titanium source. There is a single crystal structure which is anatase in all of the samples from the data of XRD. The SEM microphotographs of $C/TiO_2$ composites show that the $TiO_2$ particles were well mixed with the CNT. There are C, O and Al with strong Ti peaks in all samples from EDX results, and it also shows that the sample CT has much more amount of C and Ti content than that of sample HCT. Finally, the photocatalytic activities for the $C/TiO_2$ composites have more effective than that of pristine $TiO_2$.

• Journal of the Korean Ceramic Society
• /
• v.45 no.3
• /
• pp.150-156
• /
• 2008

Pitch-binded activated carbon fiber(ACF)/$TiO_2$ composite photocatalysts were prepared by Carbon Tetra Chloride (CTC) solvent mixing method with different mixing ratios of anatase to ACF. The result of the textural surface properties demonstrated that there is a slight increase in the Brunauer, Emmett and Teller (BET) surface area of composites with an increase of the amount of ACF. The surfaces structure morphologies of the composites were observed using an Scanning Electron Microscope (SEM). In the XRD patterns for all ACF/$TiO_2$ composites, the diffraction peaks showed the formation of anatase crystallites. The EDX spectra showed the presence of C, O and Si with strong Ti peaks. Most of these samples were richer in carbon and major Ti metal than any other elements. From the photo-decomposition results, the excellent activity of the ACF/$TiO_2$ composites between c/$c_0$ for methylene blue and UV irradiation time could be attributed to both the effects of the photocatalysis of the supported $TiO_2$ and adsorptivity of activated carbon fiber and another carbon derived from pitch.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.671-674
• /
• 2003

Generally, $TiO_2$ powders absorb ultraviolet rays and make oxidation/reduction reactions on its surface. Hydroxide radical(OH), a product of photocatalyst reactions, has so strong oxidation/reduction electric potential that it can oxidize noxious gas like NOx. In this study, $TiO_2$ was substituted for cement to investigate the purifying degree of NOx. Rutile and anatase types of $TiO_2$ were used as photocatalyst. The sun rays and the ultraviolet were used as a light source. Anatase type $TiO_2$ was better than rutile type in purifying performance. The sunray showed the best purifying performance among the light sources. 3% substitution of TiO$_2$ with the sunray was enough to purify NOx efficiently.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.10
• /
• pp.33-39
• /
• 2010

A self-organized nano-structured, photocatalytic $TiO_2$ membrane with large surface area of anatase crystallites was successfully fabricated by anodization. The nano-structured anodized $TiO_2$ membrane was characterized using EDX, SEM and XRD techniques and the effect of electrolyte type and concentration to fabricate $TiO_2$ metal membrane was also investigated. Regular nano tubular arrays were obtained By the EDX, SEM and XRD patterns, the anodized $TiO_2$ membrane showed the enhanced photocatalytic properties of anatase phase. Photocatalytic activities of fabricated $TiO_2$ metal membrane was also experimentally investigated as model compound of humic acid.

• Korean Journal of Materials Research
• /
• v.11 no.1
• /
• pp.61-66
• /
• 2001

$TiO_2$films for photocatalytic reaction were synthesized by anodizing process. The photocatalytic efficiencies of anodized $TiO_2$were evaluated by the rate of decomposition of aniline blue. The properties of photocatalysis on anodic $TiO_2$films have been observed, but the efficiencies of photocatalytic reaction depended on the conditions of films formation. The microstructure of the anodic film formed in $H_2SO_4$ solution differed from that of $TiO_2$films formed in $H_2SO_4+H_3PO_4$ solution. It has been shown that the appropriate applied-voltage for anodizing of titanium for photocatalysis was 180V in both aqueous solutions.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.12
• /
• pp.3981-3986
• /
• 2012

Anatase nanocrystalline and its tungsten-doped (0.4, 2, and 4 mol %) powders have been synthesized by microwave irradiation through hydrolysis of titanium tetra-isopropoxide (TIP) in aqueous solution. The materials are characterized by XRD, Raman, SEM-EDX, TEM, FT-IR and UV-vis techniques. The nanocrystalline $TiO_2$ particles are 30 nm in nature and doping of tungsten ion decreases their size. As seen in TEM images, the crystallites of W (4 mol %) doped $TiO_2$ are small with a size of about 10 nm. The photocatalytic activity was tested on the degradation of 4-nitrophenol (4-NP). Catalytic activities of W-doped and pure $TiO_2$ were also compared. The results show that the photocatalytic activity of the W-doped $TiO_2$ photocatalyst is much higher than that of pure $TiO_2$. Degradation decreases from 96 to 50%, during 115 min, when the initial 4-NP concentration increases from 10 to 120 ppm. Maximum degradation was obtained at 35 mg of photocatalyst.

• Proceedings of the Korean Ceranic Society Conference
• /
• 2000.10a
• /
• pp.114.2-114
• /
• 2000

• Bulletin of the Korean Chemical Society
• /
• v.18 no.6
• /
• pp.640-643
• /
• 1997

Pure titanium dioxide $(TiO_2)$ films were prepared by pulsed laser deposition on a single crystal Si(100) substrate. We have investigated the growth of crystalline titanium dioxide films with respect to substrate temperature and ambient oxygen pressure. The structural properties of the films were analyzed by X-ray diffraction. We found that the anatase as well as the rutile phases could be formed from the original rutile phase of the target $TiO_2$. At 0.75 torr of ambient oxygen pressure, the structure of $TiO_2$ film was amorphous at room temperature, anatase between 300 and 600 ℃, a mixture of anatase and rutile between 700 and 800 ℃, and only rutile at 900 ℃ and above. However, at a low ambient oxygen pressure, the rutile phase became dominant; the only rutile phase was obtained at the ambient oxygen pressure of 0.01 torr and the substrate temperature of 800 ℃. Therefore, the film structures were largely influenced by substrate temperature and ambient oxygen pressure.

• Korean Journal of Materials Research
• /
• v.13 no.10
• /
• pp.691-696
• /
• 2003

To improve the photocatalyticactivity of $TiO_2$-coated coal fly ash, tungsten hydroxide was doped by impregnation method and was oxidized by heat treatment in temperature ranges of $WO^{\circ}C$ for 2 hrs. The changes of crystal structure and crystal size of $TiO_2$and $WO_3$on coal fly ash were investigated by X-ray diffraction analysis. The crystal structure of titanium dioxide showed only anatase type and $TiO_2$-$WO_3$ compounds appeared in the heat treatment temperature ranges of $500∼600^{\circ}C$. By adding $V_3$in $TiO_2$coated on fly ash, the growth of crystal size of anatase was restrained and the anatase phase was stabilized in temperature ranges of TEX>$500∼<800^{\circ}C$. And $WO_3$acted as a trap site of electrons excited from anatase by irradiating UV. The maximum removal efficiency of NO gas for $TiO_2$/$WO_3$-coated coal fly ash was 84% and appeared when the ammonium tungstate of $1.3${\times}$10^{-3}$ M was doped and then heated at $600^{\circ}C$ for 2 hrs.