• 한국재료학회지
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• 제31권1호
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• pp.8-15
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• 2021

Transparent, photocatalytic, and self-cleaning TiO2 thin film is developed by TiO2 sol-gel coating on glass and polycarbonate (PC) substrates. Acetyl acetone (AcAc) suppresses the precipitation of TiO2 by forming a yellowish (complex) transparent sol-gel. XPS analysis confirms the presence of Ti2p and O1s in the thin films on glass and PC substrates. The TiO2-sol is prepared by stabilizing titanium (IV) isopropoxide (TTIP) with diethylamine and methyl alcohol. The addition of AcAcsilane coupling solution to the TiO2-sol instantaneously turns to yellowish color owing to the complexing of titanium with AcAc. The AcAc solution substantially improves the photocatalytic property of the TiO2 coating layer in MB solutions. The coated TiO2 film exhibits super hydrophilicity without and with light irradiation. The TiO2 thin film stabilized by adding 8.7 wt% AcAc shows the highest photo-degradation for methylene blue (MB) solution under UV light irradiation. Also, the optimum photocatalytic activity is obtained for the 8.7 wt% AcAc-stabilized TiO2 coating layer calcined at 450 ℃. The thin-films on glass exhibit fast self-cleaning from oleic acid contamination within 45 min of UV-light irradiation. The appropriate curing time at 140 ℃ improves the anti-fogging and thermal stability of the TiO2 film coated on PC substrate. The watermark-free PC substrate is particularly beneficial to combat fogging problems of transparent substrates.

• 한국세라믹학회지
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• 제53권3호
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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.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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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 $TiO_2$.

• 한국환경과학회지
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• 제12권10호
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• pp.1071-1077
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• 2003

The aim of this study is, firstly, to find out what kinds of inorganic species are produced in the photocatalytic oxidation of ammonium-nitrogen containing water and, secondly, to seek the influence of anion for the photocatalytic oxidation of ammonium contained compounds. The photoenergy above 3 eV(λ <415 nm) was effectively absorbed by TiO$_2$ and TiO$_2$/polymer was used to be oxidized NH$_4$-N in wastewater to NO$_3$-N. Existing the anion as Cl$\^$-/, the rate of photocatalytic oxidation decreased regardless of other condition. This result showed that the chloride ions reduced the rate of oxidation by scavenging oxidizing radical species as OH$\^$-/ and OCl$\^$-/. Some of the added ion might have blocked the active sites of the catalyst surface, thus deactivated the catalyst.

• Nano
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• 제13권11호
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• pp.1850129.1-1850129.10
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• 2018

To improve the high charge carrier recombination rate and low visible light absorption of {001} facets exposed $TiO_2$ [$TiO_2(001)$] nanosheets, few-layered $MoS_2$ nanoparticles were loaded on the surfaces of $TiO_2(001)$ nanosheets by a simple photodeposition method. The photocatalytic activities towards Rhodamine B (RhB) were investigated. The results showed that the $MoS_2-TiO_2(001)$ nanocomposites exhibited much enhanced photocatalytic activities compared with the pure $TiO_2(001)$ nanosheets. At an optimal Mo/Ti molar ratio of 25%, the $MoS_2-TiO_2(001)$ nanocomposites displayed the highest photocatalytic activity, which took only 30 min to degrade 50 mL of RhB (50 mg/L). The active species in the degradation reaction were determined to be $h^+$ and $^{\bullet}OH$ according to the free radical trapping experiments. The reduced charge carrier recombination rate, enhanced visible light utilization and increased surface areas contributed to the enhanced photocatalytic performances of the 25% $MoS_2-TiO_2(001)$ nanocomposites.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2660-2664
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• 2014

A simple method of depositing titanium dioxide ($TiO_2$) nanoparticles onto graphene oxide (GO) as a catalytic support was devised for photocatalytic degradation of methylene blue (MB). Thiol groups were utilized as linkers to secure the $TiO_2$ nanoparticles. The resultant GO-supported $TiO_2$ (GO-$TiO_2$) sample was characterized by transmission electron microscopy (TEM), near-edge X-ray absorption fine structure (NEXAFS), and X-ray photoelectron spectroscopy (XPS) measurements, revealing that the anatase $TiO_2$ nanoparticles had effectively anchored to the GO surface. In the photodegradation of MB, GO-$TiO_2$ exhibited remarkably enhanced photocatalytic efficiency compared with thiolated GO and pure $TiO_2$ nanoparticles. Moreover, after five-cycle photodegradation experiment, no obvious deactivation was observed. The overall results showed that thiolated GO provides a good support substrate and, thereby, enhances the photodegradation effectiveness of the composite photocatalyst.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2480-2486
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• 2018

Mesoporous $TiO_2$ microspheres were prepared by spray pyrolysis for photocatalysis. Post modification of $TiO_2$ by heat treatment was performed to optimize its photocatalytic performance. First, spherical $TiO_2$ particles with mesoporous structure were synthesized at pyrolysis temperatures of 500, 600, and $700^{\circ}C$. After characterization by XRD, SEM, and $N_2$ adsorption, a sample prepared at $500^{\circ}C$ was found to possess desirable properties for photocatalytic performance through post-modification. In methylene blue degradation, mesoporous $TiO_2$ microspheres synthesized at $500^{\circ}C$ outperformed other microspheres. Furthermore, samples obtained by spray pyrolysis at $500^{\circ}C$ were calcined at various temperatures as a post-modification process. The sample calcined at $350^{\circ}C$ showed improved photocatalytic activity due to optimal anatase crystallinity and surface area.

• Bulletin of the Korean Chemical Society
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• 제30권1호
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• pp.193-196
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• 2009

Mesoporous $TiO_2$ material was synthesized from diblock copolymers with ethylene oxide chains via a sol-gel process in aqueous solution. The properties of these materials were characterized with several analytical techniques including field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), wide angle X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, and Barrett-Joyner-Halenda (BJH) analysis. The mesoporous $TiO_2$ materials calcined at 400${^{\circ}C}$ were found to have specific surface areas 212 $m^2g^-1$, average pore sizes 6.2 nm, and their average crystal sizes were found to be 8.2 nm. The photocatalytic activity of mesoporous $TiO_2$ was characterized with UV-Vis spectroscopy, and it was found to be 5.8 times higher than that of Degussa P25 $TiO_2$ (P25). For deactivation of Escherichia coli, mesoporous $TiO_2$ also has high photocatalytic inactivity than that of P25. Such a high photocatalytic activity is explained with large surface area and small crystal size with wormhole-like mesoporous structure.

• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1895-1899
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• 2012

$SiO_2$-coated $TiO_2$ composite materials with enhanced photocatalytic activity under UV light was prepared by a simple catalytic hydrolysis method. XRD, TEM, UV-vis spectroscopy, Photoluminescence, FT-IR and XP spectra were used to characterize the prepared samples. The obvious shell-core structure was shown for obtained $SiO_2$@$TiO_2$ sample. The average thickness of the $SiO_2$ coating layer was 2-3 nm. The interaction between $SiO_2$ and $TiO_2$ restrained the recombination of excited electrons and holes. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under UV light. The photocatalytic activity of $SiO_2$@$TiO_2$ was much higher than that of P25 and mechanical mixing sample $SiO_2/TiO_2$. The possible mechanism for the photocatalysis was proposed.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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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.