• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.173-176
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• 2011

The characteristic changes in ZnO thin film according to H- and O- plasma treatments have been studied by Photoluminescence (PL) spectroscopy at room temperature. The red shift of UV peak by 20-30 meV in PL spectra after plasma treatments is identified, which indicates that there are changes in the binding energy of bound exciton and/or the movement of energy levels of lattice defects and impurities. The width of UV peak is decreased after plasma treatments, which is believed to be closely related to the crystal quality of ZnO film. The increase of UV peak intensity after H-plasma treatment is also observed, and this could mean that the radiative recombination is strengthened because the hydrogen atoms in the plasma diffuse into the film where they passivate and neutralize the defects and the impurities.

• Korean Journal of Materials Research
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• v.26 no.2
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• pp.73-78
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• 2016

$TiO_2$ nanoparticles were synthesized by a sol-gel process using titanium tetra isopropoxide as a precursor at room temperature. Ag-doped $TiO_2$ nanoparticles were prepared by photoreduction of $AgNO_3$ on $TiO_2$ under UV light irradiation and calcinated at $400^{\circ}C$. Ag-doped $TiO_2$ nanoparticles were characterized for their structural and morphological properties by X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and transmission electron microscopy (TEM). The photocatalytic properties of the $TiO_2$ and Ag-doped $TiO_2$ nanoparticles were evaluated according to the degree of photocatalytic degradation of gaseous benzene under UV and visible light irradiation. To estimate the rate of photolysis under UV (${\lambda}=365nm$) and visible (${\lambda}{\geq}410nm$) light, the residual concentration of benzene was monitored by gas chromatography (GC). Both undoped/doped nanoparticles showed about 80 % of photolysis of benzene under UV light. However, under visible light irradiation Ag-doped $TiO_2$ nanoparticles exhibited a photocatalytic reaction toward the photodegradation of benzene more efficient than that of bare $TiO_2$. The enhanced photocatalytic reaction of Ag-doped $TiO_2$ nanoparticles is attributed to the decrease in the activation energy and to the existence of Ag in the $TiO_2$ host lattice, which increases the absorption capacity in the visible region by acting as an electron trapper and promotes charge separation of the photoinduced electrons ($e^-$) and holes ($h^+$). The use of Ag-doped $TiO_2$ nanoparticles preserved the option of an environmentally benign photocatalytic reaction using visible light; These particles can be applicable to environmental cleaning applications.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.425.2-425.2
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• 2014

$TiO_2$ possesses great photocatalytic properties but absorbs only UV light owing to high band gap energy (Eg = 3.2 eV). By narrowing the band gap through doping a metal ion, the photocatalytic activity can be enhanced in condition of the light of a higher than 365 nm wavelength. Main purpose for this study is to evaluate the activities of metal doped $TiO_2$ for degrading the volatile organic compounds (VOCs); p-xylene is chosen in the VOC removal test. Vanadium is selected in this study because an ionic radius of vanadium is almost the same as titanium ion and vanadium can be easily doped into $TiO_2$. V-doped $TiO_2$ was synthesized by sol-gel methods and compared with pure $TiO_2$. Pure TiO2 powder and V-doped $TiO_2$ powder were coated on glasses by spray coating method. UV-Visible spectrophotometer was used for the measurement of the band gap changes. VOC concentration degradation level was tested with using various UV light sources in an enclosed chamber. Catalytic activities of prepared samples were evaluated based on the experimental results and compared with coated pure $TiO_2$ sample.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.40 no.5
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• pp.53-59
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• 2008

This study was carried out to investigate the effect of photocatalysis using $TiO_2$ and UV applied for the COD reduction of wastewater in linerboard mill. Trials were done to obtain the optimum addition amounts of $TiO_2$ and $H_2O_2$ to the wastewater and find an appropriate pH condition for photocatalysis on $TiO_2$ for degrading COD. The photocatalytic reaction was applied to the wastewater collected after secondary activated sludge treatment in WWTP of linerboard mill. The optimum application of photocatalysis reaction was obtained under the addition conditions of 2 g/L of $TiO_2$ and 200 mg/L of $H_2O_2$ at pH 3.0, respectively. The removal efficiency of $SCOD_{Cr}$ by photocatalytic treatment was 86.4 % and higher than Fenton treatment in which removal efficiency was 67.4 %. It was concluded that the photocatalytic process using $TiO_2$ and UV could be applied to the wastewater treatment in linerboard mill and also to the dramatic drop-off in NBDCOD load from wastewater of tertiary treatment in WWTP.

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.157-163
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• 1995

The ultraviolet blocking agents used to skincare are largely classified ultraviolet scattering agent and ultraviolet absorbent agents. There are UVC, UVB, and UBA in ultraviolet ray(UV) showing shorter wavelength than visible light. Both visible light and UVA give rise to 1st dark-skinned phenomena. On exposure of the skin to UV, phenomena of skin variation are termed sunburn or suntan. There are chronic and acute adverse reactions in skin response to UV. The latter is caused by UVB, which has mainly effects on the skin. But lately due to destruction of ozone layer, UVA has more serious irritation on the skin than UVB. In this paper spectrometric properties of UV absorbent agents such as PABA, octyl-PABA, Urocanic acid, and 2-hydroxy-4-methoxy benzophenone in vitro have been investigate. As results, it was found that the three fomer were more suitable than the last. UV scattering measurements on the sample used inorganic pigments showed that pigments containing titanium dioxide had a better scattering effects than the inorganic pigments such as $Fe_2O_3$, $Al_2O_3$, etc.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.829-832
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• 2004

The pure product of 2,3-diaminophenazine was prepared by the enzyme-catalyzed reaction of ophenylenediamine-$H_2O_2$-horseradish peroxidase and characterized by UV/Vis spectroscopy, IR spectroscopy and NMR spectroscopy. The electrochemical behaviour of 2,3-diaminophenazine on the glassy carbon electrode was studied. The interaction between 2,3-diaminophenazine and deoxyribonucleic acid was studied by cyclic voltammetry method and UV/Vis spectroscopy, which indicated that the interaction between them is intercalation. The influence of reacting time was also studied. The binding ratio of the 2,3-diaminophenazine-DNA complex is calculated to be 1 : 2 and the binding constant is to be $5.07{\times} 10^3L{\cdot}mol^{-1}$ at room temperature.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.102.1-102.1
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• 2007

• Journal of the Korean Ceramic Society
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• v.41 no.5
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• pp.359-363
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• 2004

Photoluminescence excitation (PLE) spectroscopy studies were performed for anodically etched porous Zn, which exhibited a PL in the blue/violet spectral range peaking at 420 nm (2.95 eV), and oxidzed porous Zn at 380$^{\circ}C$ for 10 min and 12 h. A broad absorption band was observed at 4.07 eV (305 nm), 3.49 (355 nm) for anodically etched porous Zn. In contrast, both the oxidized porous Zn and sintered ZnO exhibited an almost identical one broad absorption band at 3.85 eV (322 nm), when PLE spectra were measured at 378 nm (3.28 eV). The oxidized porous Zn and sintered ZnO, which displayed both UV and green luminescence band, showed an additional absorption band at 389 nm (3.19 eV) and 467 nm (2.66 eV). In contrast, no significant absorption band was detected for a 10-min oxidized porous Zn, which only displayed one UV luminescence void of deep-level luminescence. These absorption bands determined by PLE studies enabled a clear understanding of an emission mechanism for the UV and green luminescence from ZnO.

• Journal of the Korean Applied Science and Technology
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• v.39 no.1
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• pp.34-41
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• 2022

As the use of chemical products increases in daily life, the removal of dye waste has also emerged as an important environmental issue. This dye waste can be decomposed using a photocatalyst, and the photocatalyst can be synthesized very cost-effectively by using the sol-gel technology. The sol-gel technology is not only very useful for nanoscale film formation, but also can simply form multilayer structures. Using a multiple spin coating method, in this study, a ZnO film with a multilayered structure (3 layers, 5 layers) was formed by using zinc oxide (ZnO), which is effective in decomposing various dyes. For performance comparison, a ZnO film having a single layer structure by a single spin coating method was prepared as a control. Structural and elemental analysis of ZnO film was performed using an X-ray diffraction analyzer and an energy dispersive X-ray spectrometer. A nanowire-like surface morphology could be observed through a scanning electron microscope. Additionally, UV-Vis spectrophotometer was used to measure the absorbance of UV light. The ZnO film with a five-layer structure degraded the simulated methylene blue by 49% more than the ZnO film with a single-layer structure. In conclusion, it was found that ZnO having a multilayered structure is useful as a photocatalyst that decomposes methylene blue dye more effectively.

• Journal of the Korean Applied Science and Technology
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• v.23 no.2
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• pp.153-159
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• 2006

The photocatalytic degradation of methylene blue(MB) was investigated using $TiO_2$ as photocatalyst and UV radiation. $TiO_2$ supported with activated carbon(AC) was prepared by SOL-GEL method and depended on several parameters such as the mass ratio of $TiO_2/AC$, pH and experimental time. The presence of the anatase and rutile crystal phase was determined by XRD analyses of the prepared $TiO_2$. The degradation of MB with $TiO_2/AC$ was about 20% higher than that of AC alone. A variation of photodegradation was negligible under UV radiation conditions ( ${\geq}$ 40W). It was experimentally showed that the photodegradation rate was increased with increasing the amount of photocatalyst. The optimal catalyst was prepared by impregmation of $5wt%-TiO_2$ with AC and was calcined at $300^{\circ}C$, and showed about 99% removal efficiency for 3hrs.