• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3031-3038
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• 2009

Cobalt-loaded activated carbon fibers (ACFs) supported titanium dioxide ($TiO_2$) photocatalyst was developed by sol-gel method. The Co-ACFs/$TiO_2$ photocatalyst were characterized by scanning electron microscope (SEM), X.ray diffraction patterns (XRD), energy dispersive X.ray analysis (EDX) and UV-vis absorption spectroscopy. Decomposition efficiency of methylene blue (MB) solution by Co-ACFs/$TiO_2$ photocatalyst reached almost 100% under 300 min reaction. The MB molecules in the bulk solutions were supposed to be condensed around $TiO_2$ particles by adsorption of ACFs. Therefore, the photocatalyst possesses the combined effect of adsorption by activated carbon fibers and photocatalytic reactivity of $TiO_2$ on MB degradation. Due to the cobalt has electron transition effece, thus improved the photodegradation of MB solution.

• Environmental Engineering Research
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• v.14 no.1
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• pp.32-40
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• 2009

In this study, we have prepared three kinds of carbon nanometer tube $CNT/TiO_{2}$ electrodes through impregnation with different concentration titanium n-butoxide (TNB) solution. The prepared electrodes were characterized with surface properties, structural crystallinity, elemental identification and photoelectrocatalytic activity. The $N_2$ adsorption data showed that the composites had decreased surface area compared with the pristine CNT. This indicated the blocking of micropores on the surface of CNT, which was further supported by observation via SEM. XRD results showed patterns for the composites and a typical single and clear anatase crystal structure. The main elements such as C, O and Ti were existed for all samples from the EDX data. The catalytic efficiency of the developed electrode was evaluated by the photoelectrodegradation of methylene blue (MB). The positive potential applied in photoelectrocatalytic (PEC) oxidation was studied. It was found that photoelectrocatalytic (PEC) decomposition of MB solution could be attributed to combination effects between $TiO_2$ photocatalytic and CNT electro-assisted. Through the comparison between photocatalytic (PC) oxidation and photoelectrocatalytic (PEC) oxidation, it was found that the PEC oxidation efficiency for MB is higher than that of PC oxidation.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.139-144
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• 2014

Activated carbon fiber (ACF) was modified with MnS nanoparticles to prepare MnS-ACF, and it was employed for preparation of MnS-$ACF/TiO_2$ composites with titanium (IV) n-butoxide (TNB). The properties of MnS-$ACF/TiO_2$ composites were characterized by XRD, SEM, and EDX. EDX results showed the presence of C, O, and Ti as major elements and traces of the metal elements Mn and S. The photocatlytic activity was evaluated by degradation of methyl blue (MB) and methyl orange (MO) dye. The results demonstrated that as-prepared samples could effectively photodegrade MB and MO under UV irradiation. Subsequently, the decomposition of MB solution showed the combined effects of adsorptions by ACF and enhanced photocatalytic effect by $TiO_2$. Finally, the photocatalytic effect increased due to photo-induced-electron absorption effect by ACF and electron trap effect by comodified MnS nanoparticles.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.366-366
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• 2011

이성분 산화물인 ZnO/$TiO_2$ core-shell 나노입자는 core-shell 구조의 특성과 이성분 산화물의 상호작용에 의해서 염료감응형 태양전지의 효율향상을 기대할 수 있다. Znic acetate($Zn_2(CH_3COO)$)와 Titanium(IV) butoxide($Ti(OBu)_4$)를 이용하여 ZnO 나노입자를 수열합성하고 그 주의에 $TiO_2$을 가수분해 반응을 이용하여 둘러싸는 core-shell형태의 물질을 합성하였다. 그 이후 결정성 및 유기물 제거를 위해서 4시간 동안 고온에서 소성하였다. SEM 결과에 따르면 소성 온도를 600도까지 증가시키면 ZnO의 경우 나노입자의 크기가 증가하는 경향을 확인하였다. 하지만 core-shell의 경우는 ZnO의 뭉침현상을 $TiO_2$이 방해하여 초기합성된 크기와 동일한 크기를 유지하는 것을 확인하였다. 또한 XRD 결과에 따르면 주변에 형성된 $TiO_2$ 이외에 $Zn_2TiO_4$의 spinel 구조를 가지는 물질이 합성되는 것을 확인할 수 있었다. 합성된 core-shell 구조의 나노입자는 약 40~50 nm의 크기를 가지고 600도에서 소성된 입자의 경우 산소 정공이 거의 없는 약 3 eV의 밴드갭을 가지는 물질로 합성이 되었다. Core-shell 나노입자의 경우 염료 감응형 태양전지의 반도체 물질로 응용 가능할 것으로 판단된다.

• Korean Journal of Materials Research
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• v.25 no.5
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• pp.247-252
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• 2015

The effect of precursor concentration on the structural, morphological, and optical properties of $TiO_2$nano-flowers was investigated in this study. An increase in crystallite size was observed with an increase in the concentration of the precursor (titanium butoxide). The FE-SEM micrographs of the as-prepared samples show a three-dimensional flower-like morphology. The flowers consist of several nanorods coming out of a single core and have very sharp edges. Also, the variation in the aspect ratio of the nanostructure was observed with the concentration of the precursor. The photocatalytic properties of the samples show that the sample that has a high aspect ratio (AR~9) has a much better photocatalytic activity compared to the nano-crystal with a low aspect ratio (AR~6.1). It is believed that the excellent photocatalytic performance and short time synthesis of $TiO_2$nano-flowers using the microwave hydrothermal method can have potential applications in the field of photocatalysis.

• Macromolecular Research
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• v.13 no.1
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• pp.73-79
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• 2005

Poly(L-lactic acid-co-succinic acid-co-l,4-butane diol) (PLASB) was synthesized by direct condensation copolymerization of L-lactic acid (LA), succinic acid (SA), and 1,4-butanediol (BD) in the bulk using titanium(IV) butoxide as a catalyst. The weight-average molecular weight ofPLASB was $2.1{\times}10^{5}$ when the contents of SA and BD were each 0.5 mol/100 mol of LA. Electrospinning was used to fabricate porous membranes from this newly synthesized bioabsorbable PLASB dissolved in mixed solvents of methylene chloride and dimethylformamide. Scanning electron microscopy (SEM) images indicated that the fiber diameters and nanostructured morphologies of the electrospun membranes depended on the processing parameters, such as the solvent ratioand the polymer concentration. By adjusting both the solvent mixture ratio and the polymer concentration, we could fabricate uniform nanofiber non-woven membranes. Cell proliferation on the electrospun porous PLASB membranes was evaluated using mouse fibroblast cells; we compare these results with those of the cell responses on bulk PLASB films.

• Polymer(Korea)
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• v.29 no.1
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• pp.41-47
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• 2005

The transesterification of dimethyl terephthalate (DMT) with 1,3-propanediol (PDO) was investigated in the presence of catalyst, titanium (IV) butoxide (TBO), at 175~190 $^{\circ}C$ . The degree of transesterification reaction was measured by the output of methanol which was distilled from the reactor. The amount of methanol increased as the reaction temperature, molar ratio and catalyst concentration increased. The observed overall rate of the transesterification was third order; first order with respect to DMT, PDO, and the concentration of catalyst, respectively. Using calculated rate constants, the activation energy for transesterification was 26.93 kcal/mole. The melting temperature of bis(2-hydroxytrimethyl) terephthalate (BHTMT) was 85.2$^{\circ}C$ and heat of fusion 141.3 J/g.

• Polymer(Korea)
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• v.24 no.3
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• pp.299-305
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• 2000

In order to increase the thermal stability at high temperatures, new hybrid ceramic percursors were synthesized by chemical modification of polycarbosilane (PCS). The structure of hybrid ceramic percursors were investigated by using FT-IR and $^1$H-NMR spectrometers. The syntheses of hybrid ceramic precursors were confirmed by monitoring the change of the adsorption peaks appearing at 0893, 1092, 609 $cm^{-1}$ / on the FT-IR spectra, and also by the presence of peaks at 3.8, 2.0, 0.6 ppm on the $^1$H-NMR spectra. The conversion of hybrid ceramic percursor was around 74 and 10 wt% higher than that of the pure PCS. After the heat-treatment at 150$0^{\circ}C$, the crystalline peaks for $\beta$-SiC were observed at 2$\theta$=35.7, 42.2, 61.0$^{\circ}$ on the X-ray powder diffractogram. It showed the conversion of hybrid ceramic percursor to crystalline $\beta$-SiC.