• Applied Chemistry for Engineering
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• v.32 no.2
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• pp.125-131
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• 2021

Semiconductor-based photocatalysts can only be activated with ultraviolet or visible light due to their intrinsic bandgap, and they cannot use the energy in the near-infrared region, which accounts for about 50% of solar energy. Therefore, in order to improve the performance of the semiconductor photocatalyst, it is necessary to utilize more solar energy in a broad band ranging from ultraviolet to near-infrared. Combining upconversion nanoparticles with semiconductor photocatalysts for near-infrared absorption have thus been reported. Upconversion nanoparticles can sequentially absorb multiple near-infrared photons and convert them into ultraviolet or visible to activate photocatalysts. In addition, by coupling the semiconductor photocatalyst and the upconversion nanoparticles with the plasmonic metal nanoparticles, the photocatalytic activity can be further improved. This review summarizes the recent studies on improving the photocatalytic performance with near-infrared absorption by using upconversion nanoparticles.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.932-938
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• 2005

[ $TiO_2$ ] nanoparticles were prepared from the precipitation in $TiCl_4$ and the sol-gel profess in $Ti(OC_3H_7)_4$ as starting materials with various synthetic conditions. The samples were characterized by XRD, SEM, and TEM testing techniques. The photocatalytic degradation of congo red has been investigated in $TiO_2/UV$ process to evaluate photocatalytic activities for the samples. $TiO_2$ nanoparticles calcined at $400^{\circ}C$ had the best photocatalytic activity with the rate constant of the degradation of congo red as $0.0319\;min^{-1}$. The rate constant of $TiO_2$ photocatalysts was increased with the calcination temperature under $400^{\circ}C$ and decreased with the calcination temperature upper $400^{\circ}C$. In the case of $TiO_2$ photocatalysts, the photocatalytic activity wasn't greatly affected by the frequencies of usage. In the similar synthesis condition, the degradation efficiency of the $TiO_2$ particle prepared by $TiCl_4$ was increased to 8.8%, when the rate was compared with the sample prepared by $Ti(OC_3H_7)_4$. The photocatalytic activities of $TiO_2$ photocatalysts synthesized by $Ti(OC_3H_7)_4$ with various conditions were also discussed.

• Clean Technology
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• v.26 no.4
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• pp.311-320
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• 2020

In this study, the photocatalytic degradation of rhodamine B (RhB), methyl orange (MO) and methylene blue (MB) was carried out under visible light irradiation using CdS and CdZnS/ZnO photocatalysts prepared by a simple precipitation method. This study focused on examining the effect of physicochemical properties of dye and photocatalyst on the reaction pathway of photocatalytic degradation. The prepared photocatalysts were characterized by XRD, UV-vis DRS and XPS. Both the CdS and CdZnS/ZnO photocatalysts exhibit an excellent absorption in the visible light and the UV light regions. It was observed that the photocatalytic degradation of MO proceeds via the same reaction mechanism on both the CdS and CdZnS/ZnO photocatalysts. However, the photocatalytic degradation of RhB and MB was found to proceed through a different reaction pathway on the CdS and CdZnS/ZnO catalysts. It is interesting to note that MB dimer was formed on the CdS catalyst at the beginning of the photocatalytic reaction, while the MB monomer was degraded during the overall photocatalytic reaction on CdZnS/ZnO. The above results may be mainly ascribed to the difference of band edge potential of the conduction band in the CdS and CdZnS/ZnO semiconductors and the adsorption property of dye on the catalysts.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2008.04a
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• pp.416-417
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• 2008

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.469-470
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• 2010

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2010.04a
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• pp.467-468
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• 2010

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2009.10a
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• pp.428-429
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• 2009

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2011.06a
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• pp.287-287
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• 2011

• Korean Journal of Materials Research
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• v.19 no.9
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• pp.481-487
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• 2009

The photocatalysts of Fe-ACF/$TiO_2$ compositeswere prepared by the sol-gel method and characterized by BET, XRD, SEM, and EDX. It showed that the BET surface area was related to adsorption capacity for each composite. The SEM results showed that ferric compound and titanium dioxide were distributed on the surfaces of ACF. The XRD results showed that Fe-ACF/$TiO_2$ composite only contained an anatase structure with a Fe mediated compound. EDX results showed the presence of C, O, and Ti with Fe peaks in Fe-ACF/$TiO_2$ composites. From the photocataytic degradation effect, $TiO_2$ on activated carbon fiber surface modified with Fe (Fe-ACF/$TiO_2$) could work in the photo-Fenton process. It was revealed that the photo-Fenton reaction gives considerable photocatalytic ability for the decomposition of methylene blue (MB) compared to non-treated ACF/$TiO_2$, and the photo-Fenton reaction was improved by the addition of $H_2O_2$. It was proved that the decomposition of MB under UV (365 nm) irradiation in the presence of $H_2O_2$ predominantly accelerated the oxidation of $Fe^{2+}$ to $Fe^{3+}$ and produced a high concentration of OH radicals.

• Advances in environmental research
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• v.3 no.1
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• pp.11-28
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• 2014

Advanced oxidation processes using UV and catalysts like $TiO_2$ and ZnO have been recently applied for the photocatalytic degradation of MTBE in water. Attempts have been made to replace the UV radiation by the solar spectrum. This review intends to shed more light on the work that has been done so far in this area of research. The information provided will help in crystallizing the ideas required to shift the trend from UV photocatalysis to sunlight photocatalysis. The careful optimization of the reaction parameters and the type of the dopant employed are greatly responsible for any enhancement in the degradation process. The advantage of shifting from UV photocatalysts to visible light photocatalysts can be observed when catalysts like $TiO_2$ and ZnO are doped with suitable metals. Therefore, it is expected that in the near future, the visible light photocatalysis will be the main technique applied for the remediation of water contaminated with MTBE.