• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.34-34
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• 2010

Activities of various $TiO_2$ nanostructures in photocatalytic decomposition of methylene blue and toluene were determined in order to shed light on the relationship between structures and photocatalytic activity. Commercially available P-25 samples were used in the present work. In addition, $TiO_2$ nanostructures were synthesized using atomic layer deposition (ALD). We show that change in the surface structure of $TiO_2$ upon variois surface treatments results in variation in photocatalytic activity. In particular, increase in the number of OH groups on the surface leads to the enhancement in photocatalytc activity. Surface OH groups increases adsorption reactivity of organic reactants, thereby increasing activity in photocatalytic decomposition of methylene blue and toluene.

• Journal of the Korean Ceramic Society
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• v.47 no.5
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• pp.433-438
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• 2010

Fe-carbon/$TiO_2$ composites were prepared by a sol-gel method using AC, ACF, CNT and $C_{60}$ as carbon precursors and were characterized by means of BET surface area, X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The activity of the prepared photocatalysts was investigated by degradation reaction of methylene blue (MB) irradiated with UV lamp. Effects of different carbon sources and irradiation time on photocatalytic activity were also investigated. The results showed that the photocatalytic activity of the Fe-carbon/$TiO_2$ composites was much higher than that of pristine $TiO_2$ and Fe/$TiO_2$ composites. The prominent photocatalytic activity of Fecarbon/$TiO_2$ composites could be attributed to both the effects of photo-adsorption and electron transfer by carbon substrate. In addition, the higher photocatalytic activity of Fe-carbon/$TiO_2$ composites can be compared with that of carbon/$TiO_2$ and Fe /$TiO_2$ composites due to cooperative effects between Fe and carbon.

• Journal of the Korean Ceramic Society
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• v.46 no.6
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• pp.621-626
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• 2009

Fe-AC/Ti$O_2$ photocatalysts were prepared by a sol-gel method. The photocatalytic properties of Fe-AC/Ti$O_2$ photocatalysts for the purification of water have been investigated. The samples were characterized by scanning electron microscopy (SEM), specific surface area (BET), X-ray diffraction analysis (XRD), and energy dispersive X-ray spectroscopy (EDX). The photocatalytic activities were evaluated by the photocatalytic oxidation of methylene blue (MB) solution. It was found that the prepared Fe-AC/Ti$O_2$ composites have an excellent photocatalytic under visible light irradiation. A small amount of Fe ions in the AC/Ti$O_2$ composites could obviously enhance their photocatalytic activity. The high activities of the Fe-AC/Ti$O_2$ composites could be attributed to the results of the synergetic effects of the enhancement of the Fe element, the photocatalytic activity of Ti$O_2$, and the adsorption of AC.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.588-588
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• 2012

Zn-doped $TiO_2$ mesoporous microspheres with high photocatalytic activity were synthesized via combined sol-gel and solvothermal methods for photocatalytic water splitting. It is found that the photocatalytic water splitting and photocatalytic degradation activity can be enhanced by doping an appropriate amount of Zn. Our results reveal that Zn doping inhibits the recombination of photo-generated charge carriers of $TiO_2$ and improves the probability of photo-generated charge carrier separation and hence the photocatalytic activity of $TiO_2$.

• Clean Technology
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• v.24 no.3
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• pp.206-211
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• 2018

Lead molybdate ($PbMoO_4$) were successfully synthesized using a facile surfactant-assisted hydrothermal process and characterized by XRD, Raman, PL, BET and DRS. We also investigated the photocatalytic activity of these materials for the decomposition of Rhodamine B under UV-light irradiation. From XRD and Raman results, well-crystallized $PbMoO_4$ crystals have been successfully synthesized with a facile surfactant-assisted hydrothermal process and had 52-69 nm particle size. The $PbMoO_4$ catalysts prepared at $160^{\circ}C$ showed the highest photocatalytic activity. The PL peak was appeared at about 540 nm at all catalysts and it was also shown that the excitonic PL signal was proportional to the photocatalytic activity for the decomposition of Rhodamine B.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.32 no.2
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• pp.161-164
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• 2019

This study describes the development of graphene-$TiO_2$ conjugates for the enhancement of the photocatalytic efficiency of $TiO_2$. Graphene-based hybrid nanomaterials have attracted considerable attention because of the unique and advantageous properties of graphene. In the proposed hybrid nanomaterial, graphene serves as an electron acceptor to ensure fast charge transfer. Effective charge separation can, therefore, be achieved to slow down electron-hole recombination. This results in an enhancement of the photocatalytic activity of $TiO_2$. In addition, increased adsorption and interactions with the adsorbed reagents also lead to an improvement in the photocatalytic activity of graphene-$TiO_2$ hybrid nanomaterials. The acquired result is encouraging in that the photocatalytic activity of $TiO_2$ was initiated using visible light (630 nm) instead of the typical UV light.

• 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.

• Nano
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• v.13 no.10
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• pp.1850117.1-1850117.11
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• 2018

Sulfated $TiO_2$ nanoparticles were successfully immobilized on zeolite through improving hydrolysis-deposition method. Microstructure, crystallization, surface state and surface area of composite catalysts were characterized by SEM, XRD, FTIR spectra, XPS and BET and the photocatalytic activity was evaluated by degradation of methyl orange under UV irradiation. We optimized these factors ($SO^{2-}_4$ ions, calcination temperature and loading amount of sulfated $TiO_2$) on photocatalytic activity and crystallization of composite photocatalysts. The results indicated that the $SO^{2-}_4$ ions are successfully immobilized on the surface of $TiO_2$, and sulfated $TiO_2$/zeolite show the highest photocatalytic activity for methyl orange at the $[SO^{2-}_4 ]/[Ti^{4+}]$ molar rate of 1:1, calcination temperature of $600^{\circ}C$ for 2 h, and sulfated $TiO_2$ loading amount of 40%, respectively.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.425-425
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• 2011

The photocatalytic decomposition of toluene gas was investigated with $TiO_2$ on nano-diamond powder (NDP) under UV irradiation. Atomic layer deposition (ALD) was used for the growth of $TiO_2$ on the NDP. The structure and surface properties of catalysts were characterized by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The photocatalytic activity for the toluene decomposition was evaluated by measuring the concentration change of toluene and $CO_2$ gas with gas chromatography (GC)-flame ionization detector (FID) system. The photocatalytic activities of $TiO_2$/NDP catalysts were compared with that of P-25. The rate of initial photocatalytic decomposition of toluene for the $TiO_2$/NDP catalysts was relatively lower when compared to P-25. The photocatalytic activity of P-25 was rapidly decreased with time, whereas, the deactivation of $TiO_2$/NDP catalysts was less pronounced. Therefore, as the reaction time increased, the photocatalytic activity of $TiO_2$/NDP catalysts became higher than that of P-25. The intermediates such as benzaldehyde or benzoic acid, etc were more easily adhered to the active site on the P-25 surface during reaction, resulting in easier deactivation of P-25. These results could be confirmed using FT-IR spectroscopy. We suggest that the NDP used as substrate can reduce the deactivation of $TiO_2$ on the surface.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.436-437
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• 2006

The $Ag/TiO_{2-x}N_x$ nanoparticles were synthesized by photochemical deposition in a $TiO_{2-X}N_X$ suspension system. The prepared products were characterized by means of XRD, Uv-vis and photoluminescence spectra (PL). Its photocatalytic activity was investigated by the decomposition of methylene blue (MB) solution under illumination of visible and ultraviolet light, respectively. Compared to $TiO_{2-x}N_x$, the photocatalytic activity of the as-prepared $Ag/TiO_{2-x}N_x$ is obviously enhanced due to the decreasing recombination of a photoexcitated electron-hole pairs. The Mechanism in which photocatalytic activity is enhanced has been discussed in detail.