• Korean Journal of Materials Research
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• v.20 no.10
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• pp.535-542
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• 2010

In this study, we used coal-based activated carbons and charcoal as startingmaterials, phenolic resin (PR) as a binder, and TOS as a titanium source to prepare $TiO_2$ combining spherical shaped activated carbon photocatalysts. The textural properties of the activated carbon photocatalysts (SACP) were characterized by specific surface area (BET), energy dispersive X-ray spectroscopy (XRD), scanning electron microscopy (SEM), iodine adsorption, strength intensity, and pressure drop. The photocatalytic activities of the SACPs were characterized by degradation of the organic dyes Methylene Blue (MB), Methylene Orange (MO), and Rhodamine B (Rh. B) and a chemical oxygen demand (COD) experiment. The surface properties are shown by SEM. The XRD patterns of the composites showed that the SACP composite contained a typical single, clear anatase phase. The EDX spectro for the elemental indentification showed the presence of C and O with Ti peaks. According to the results, the spherical activated carbon photocatalysts sample of AOP prepared with activated carbon formed the best spherical shape, a high BET surface area, iodine adsorption capability and strength value, and the lowest pressure drop, and the photocatalytic activity was better than samples prepared with charcoal. We compared the degradation effects among three kinds of dyes. MB solution degraded with the SACP is better than any other dye solutions.

• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.343-348
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• 2016

Manganese and $TiO_2$ grown on Activated Carbon Fiber (ACF) was synthesized by hydrothermal method. The prepared composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive X-ray (EDX). The catalytic behavior was investigated through the decomposition of methylene blue (MB) and methyl orange (MO) as standard dyes under visible light. The degradation performance of the degraded standard dye solutions was determined by UV-Vis spectrophotometry. This enhanced photocatalytic activity arises from the positive synergetic effect among the Mn, $TiO_2$ and ACF in this heterogeneous photocatalyst. The process contributes to the release of abundant photocatalytic sites of Mn and $TiO_2$ and improves the photocatalytic efficiency. The excellent adsorption and photocatalytic effect with the explanation of the synergetic mechanism are very useful not only for fundamental research but also for potential practical applications.

• Applied Science and Convergence Technology
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• v.24 no.4
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• pp.96-101
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• 2015

Quantitative evaluation of photocatalytic activity of oxide nanoparticles in aqueous solution is quite challenging in that the kinetic reaction rate is determined by a complicated interplay among various limiting factors such as light scattering and absorption, diffusion and adsorption of reactants in condensed liquid phase, photoexcited charge separation and recombination rate, and the exact nature of active sites determined by detailed morphology and crystallinity of nanocrystals. Here, we present our simple experimental results showing that the kinetic regime of a typical photocatalytic degradation experiment over UV-irradiated $TiO_2$ nanoparticles in aqueous solution is in that dominated by the photoactivity of $TiO_2$ and its concentration. This result lays a firm ground of using the measured kinetic reaction rate in evaluating photocatalytic efficiency of oxide nanocrystals under evaluation.

• Journal of Electrical Engineering and Technology
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• v.6 no.3
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• pp.402-407
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• 2011

The current paper describes a simpler ground-type, single-plate electrowetting configuration for droplet transport in digital microfluidics without performance degradation. The simplified fabrication process is achieved with two photolithography steps. The first step simultaneously patterns both a control electrode array and a reference electrode on a substrate. The second step patterns a dielectric layer at the top to expose the reference electrode for grounding the liquid droplet. In the experiment, a $5{\mu}m$ thick photo-imageable polyimide, with a 3.3 dielectric constant, is used as the dielectric layer. A 10 nm Teflon-AF is coated to obtain a hydrophobic surface with a high water advancing angle of $116^{\circ}$ and a small contact angle hysteresis of $5^{\circ}$. The droplet movement of 1 mM methylene blue on this simplified device is successfully demonstrated at control voltages above the required 45 V to overcome the contact angle hysteresis.

• Journal of Powder Materials
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• v.24 no.4
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• pp.279-284
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• 2017

The formation mechanism and photocatalytic properties of a multiwalled carbon nanotube (MWCNT)/$TiO_2$-based nanotube (TNTs) composite are investigated. The CNT/TNT composite is synthesized via a solution chemical route. It is confirmed that this 1-D nanotube composite has a core-shell nanotubular structure, where the TNT surrounds the CNT core. The photocatalytic activity investigated based on the methylene blue degradation test is superior to that of with pure TNT. The CNTs play two important roles in enhancing the photocatalytic activity. One is to act as a template to form the core-shell structure while titanate nanosheets are converted into nanotubes. The other is to act as an electron reservoir that facilitates charge separation and electron transfer from the TNT, thus decreasing the electron-hole recombination efficiency.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.260-261
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• 2014

$TiO_2$ nanotubes (TNT) synthesized by microwave-assisted hydrothermal method by using $TiO_2-P25$ as a precursor at hydrothermal temperature $150^{\circ}C$ in 4 hours. The concentration of alkaline solution is between 4M and 10M. Samples were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) and UV-vis DRS spectroscopy. The results demonstrated the effects of the alkali concentration to the formation of nanotubes. The photocatalytic activity was investigated by degradation of Methylene Blue (MB).

• Journal of the Korean Ceramic Society
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• v.48 no.3
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• pp.211-216
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• 2011

Nickel oxide-doped ACF and $TiO_2$ composites (NiO/ACF/$TiO_2$) were prepared by a sol-gel method. The composite obtained was characterized by BET surface area measurements, X-ray diffraction, transmission electron microscopy and energy dispersive X-ray analysis. A methylene blue (MB) solution under visible light irradiation was used to determine their photocatalytic activity. Excellent photocatalytic degradation of the MB solution was observed using the $TiO_2$, Ti-ACF and NiO/ACF/$TiO_2$ composite under visible light.

• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2309-2314
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• 2012

Ag deposited N-$TiO_2$ composite nanoparticles were prepared via $NH_3$ plasma treatment. X-ray diffraction, UV-vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared $TiO_2$ samples. The plasma treatment did not change the phase composition and particle sizes of $TiO_2$ samples, but extended its absorption edges to the visible light region. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of Ag deposited N-$TiO_2$ composite nanoparticles were much higher than Ag-$TiO_2$, N-$TiO_2$, and P25. A possible mechanism for the photocatalysis was proposed.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1269-1274
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• 2012

A visible light responsive N, Mo co-doped $TiO_2$ were prepared by sol-gel method. X-ray diffraction, TEM, $N_2$ adsorption, UV-vis spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy were used to characterize the prepared $TiO_2$ samples. Doping restrained the phase transformation from anatase to rutile and reduced the particle sizes. The band gap was much narrowed after N, Mo co-doping. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activities of doped $TiO_2$ were much higher than that of neat $TiO_2$. The photocatalytic stability of N, Mo co-doped $TiO_2$ was much better than that of N doped $TiO_2$.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.181-182
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• 2023

The purpose of this study is to enhance the photocatalytic properties of a mixture of low-cost titanium dioxide and calcium carbonate through a simple mixing process. To increase the photocatalytic activity, the weight ratio of titanium dioxide to calcium carbonate was selected as a variable. Photocatalytic activity was evaluated by measuring the degradation of methylene blue and NOx under ultraviolet light. The results showed that a mixture containing 60% titanium dioxide and 40% calcium carbonate exhibited the highest photocatalytic activity.