• Analytical Science and Technology
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• v.19 no.5
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• pp.376-382
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• 2006

In this work, pitch/activated carbon/$TiO_2$ composite were prepared by $CCl_4$ solvent method with different mixing ratios. The BET surface area of pitch/activated carbon/$TiO_2$ composite has a significantly increase with increasing activated carbon content in pitch/activated carbon/$TiO_2$ composite. The surface structure and elemental compositions of the composite were studied by SEM and EDX, respectively. The SEM results were presented to the characterization of porous texture on the pitch/activated carbon/$TiO_2$ composite. And EDX data was shown the presence of C, O, S, Ti and other elements. The structural properties of the composite were studied in XRD measurements. The $TiO_2$ crystal phases of the pitch/activated carbon/$TiO_2$ composite had lots of rutile-type structure which transforms from anatase-type with a little of anatase-type structure. The photocatalytic activities of the composite were evaluated using a photo-decomposition method under UV lamp. The pitch/activated carbon/$TiO_2$ composites were observed better photocatalytic activity than that of pristine $TiO_2$.

• Korean Journal of Materials Research
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• v.22 no.2
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• pp.91-96
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• 2012

AC and ZnS modified $TiO_2$ composites (AC/ZnS/$TiO_2$) were prepared using a sol-gel method. The composite obtained was characterized by Brunauer-Emmett-Teller (BET) surface area measurements, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, scanning electron microscope (SEM) analysis, and according to the UV-vis absorption spectra (UV-vis). XRD patterns of the composites showed that the AC/ZnS/$TiO_2$ composites contain a typical single and clear anatase phase. The surface properties as observed by SEM present the characterization of the texture of the AC/ZnS/$TiO_2$ composites, showing a homogenous composition in the particles showing the micro-surface structures and morphology of the composites. The EDX spectra of the elemental identification showed the presence of C and Ti with Zn and S peaks for the AC/ZnS/$TiO_2$ composite. UV-vis patterns of the composites showed that these composites had greater photocatalytic activity under visible light irradiation. A rhodamine B (Rh.B) solution under visible light irradiation was used to determine the photocatalytic activity. The degradation of Rh.B was determined using UV/Vis spectrophotometry. An increase in the photocatalytic activity was observed. From the photocatalytic results, the excellent activity of the Y-fullerene/$TiO_2$ composites for the degradation of methylene blue under visible irradiation could be attributed to an increase in the photo-absorption effect caused by the ZnS and to the cooperative effect of the AC.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.1035-1040
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• 1999

Photocatalytic degradation of trichloroethylene has been carried out with UV-illuminated $TiO_2$-coated pyrex reactor in gas phase. Three commercial $TiO_2$ oxides were used as catalysts. The effect of reaction conditions, initial concentration of trichloroethylene, concentration of oxidant and light intensity on the photocatalytic activity were examined. Anatase-type catalyst showed higher activity than rutile-type, but P-25 catalyst showed the highest activity. The degradation rate increased with the decrease of flow rate and initial trichloroethylene concentration. It was preferable to use air as an oxidant. In addition, reactants with the water vapor decreased the activity and the degradation rate increased with the increase of light intensity, but it was very low with solar light. Photocatalytic deactivation was not observed at low concentration of trichloroethylene.

• Journal of Welding and Joining
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• v.24 no.5
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• pp.57-61
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• 2006

For the production of functional $TiO_2$-biodegradable plastic (polybutylene succinate:PBS) composite material with photocayalytic activity, we attempted to prepare $TiO_2$ coatings on PBS substrate by HVOF and plasma spraying techniques under various conditions. The microstructures of coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of coatings was evaluated by the photo degradation of gaseous acetaldehyde. The effects of primary particle size and spraying parameters on the formation behavior, photocatalytic performance of the coatings have been investigated. The results indicated that for both the HVOF sprayed $P_{200}$ and $P_{30}$ coatings, the high anatase ratio of 100% can be achieved regardless of fuel gas pressure. On the other hand, the HVOF sprayed $P_7$ coating exhibited a largely decreased anatase ratio (from 100% to 49.1%) with increasing the fuel gas pressure, which may be attributed to much higher susceptibility of heat for 7 nm agglomerated powder. HVOF sprayed $P_{200}$ and $P_{30}$ coatings show better performance as compared to that of plasma sprayed $P_{200}$ coatings owing to the higher anatase ratio. However, the HVOF sprayed $P_7$ coatings did not show the photocatalytic activity, which may result from the extremely small reaction surface area to the photocatalytic activity and low anatase ratio.

• Environmental Engineering Research
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• v.16 no.2
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• pp.81-90
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• 2011

Different weight percentages of Ag, Pt, and Au doped nano $TiO_2$ were synthesized using the acetic acid hydrolyzed sol-gel method. The crystallite phase, surface morphology combined with elemental composition and light absorption properties of the doped nano $TiO_2$ were comprehensively examined using X-ray diffraction (XRD), $N_2$ sorption analysis, transmission electron microscopic (TEM), energy dispersive X-ray, and DRS UV-vis analysis. The doping of noble metals stabilized the anatase phase, without conversion to rutile phase. The formation of gold nano particles in Au doped nano $TiO_2$ was confirmed from the XRD patterns for gold. The specific surface area was found to be in the range 50 to 85 $m^2$/g. TEM images confirmed the formation a hexagonal plate like morphology of nano $TiO_2$. The photocatalytic activity of doped nano $TiO_2$ was evaluated using 4-chlorophenol as the model pollutant. Au doped (0.5 wt %) nano $TiO_2$ was found to exhibit higher photocatalytic activity than the other noble metal doped nano $TiO_2$, pure nano $TiO_2$ and commercial $TiO_2$ (Degussa P-25). This enhanced photocatalytic activity was due to the cathodic influence of gold in suppressing the electron-hole recombination during the reaction.

• Korean Chemical Engineering Research
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• v.58 no.2
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• pp.313-318
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• 2020

Bi₂WO₆ were successfully synthesized using EGME, GL, EG and water as solvents by a conventional hydrothermal method. They were characterized by XRD, DRS, BET and SEM and we also investigated the photocatalytic activity of these materials for the decomposition of Rhodamin B under visible light irradiation. The XRD results revealed the successful synthesis well-crystallized Bi₂WO₆ crystals with Aurivillius structure when EGME and EG are used as solvents. In addition, the well-crystallized Bi₂WO₆ crystals showed the flower-like structure. The Bi₂WO₆ catalysts prepared at 180 ℃ using EGME as a solvent showed the highest photocatalytic activity. The Bi₂WO₆ catalysts prepared at mole ratio of H₂O/EGME more than 50% showed high photocatalytic activity.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.285-285
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• 2010

Zinc oxide (ZnO) is a direct band gap semiconductor with 3.37 eV, which has in a hexagonal wurtzite structure. ZnO is a good candidate for a photocatalyst because it has physical and chemical stability, high oxidative properties, and absorbs of ultraviolet light. During ZnO is irradiated by UV light, redox (reduction and oxidation) reactions will occur on the ZnO surface, generating the radicals O2- and OH. These two powerful oxidizing agents have been proven to be effective in decomposition of harmful organic materials, converting them into CO2 and H2O. Therefore, we assume that oxygen on the surface of ZnO is a very important factor in the photocatalytic activities of ZnO nanoparticles. Recently, ZnO nanoparticles are studied in various application fields by many researchers. Photocatalyst research is progressing much in various application fields. But the ZnO nanoparticles have disadvantage that is unstable in water in comparison titanium dioxide (TiO2). The Zn(OH)2 was formed at the ZnO surface and ZnO become inactive as a photocatalyst when ZnO is present in the solution. Therefore, we prepared synthesized ZnO nanoaprticles that were immersed in the water and dried in the oven. After that, we measured photocatalytic activities of prepared samples and find the cause of their phtocatalytic activity changes. The characterization of ZnO nanoparticles were analyzed by Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and BET test. Also we defined the photocatalytic activity of ZnO nanoparticles using UV-VIS Spectroscopy. And we explained changing of photocatalytic activity after the water treatment using X-ray Photoelectron Spectroscopy (XPS).

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.334-340
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• 2002

$TiO_2$-coated fly ash was synthesized by dropping method of coating agent in order to get $TiO_2$ coating layer with high photocatalytic activity on the surface of coal fly ash. The properties of the $TiO_2$ coating layer such as morphology, crystal structure, crystal size and photocatalytic activity were compared with those of the $TiO_2$-coated fly ash prepared by the traditional method of precipitation. $TiCl_4$ aqueous solution was used as a titanium stock solution and $NH_4HCO_3$ was used as a precipitant. The $TiO_2$ coating layer obtained by dropping method of coating agent was more uniform than that coated by precipitation. However, the crystal of $TiO_2$ coated by dropping method of coating agent was easy to grow by heat treatment because of the small primary particle size and bulky morphology, and its photocatalytic activity was consequently lower than that of the $TiO_2$ coated by precipitation. The $TiO_2$ coating layer obtained by both methods had a crystal structure of anatase, and the temperature of phase transformation into rutile was 90$0^{\circ}C$. The minimum crystal size of $TiO_2$ for the highest photocatalytic activity was found to be about 10nm.

• Advances in materials Research
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• v.11 no.3
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• pp.225-235
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• 2022

It includes the synthesis of pristine ZnO nanoparticles and a series of Ag-doped zinc oxide nanoparticles was carried out by reflux method by varying the amount of silver (1, 3, 5, 7 and 9% by mol.). The morphology of these nanoparticles was investigated by SEM, XRD and FT-IR techniques. These techniques show that synthesized particles are homogenous spherical nanoparticles having an average particle size of about 50-100 nm along with some agglomeration. The photocatalytic activity of the ZnO nanoparticles and Ag doped ZnO nanoparticles were investigated via photodegradation of methylene blue (MB) as a standard dye. The data from the photocatalytic activity of these nanoparticles show that 7% Ag-doped ZnO nanoparticles exhibit much enhanced photocatalytic activity as compared to pristine ZnO nanoparticles and other percentages of Ag-doped ZnO nanoparticles. Furthermore, 7% Ag-doped ZnO was made composites with sulfur-doped graphitic carbon nitride by physical mixing method and a series of nanocomposites were made (3.5, 7.5, 25, 50, 75% by weight). It was observed that the 25% composites exhibited better photocatalytic performance than pristine S-g-C 3 N 4 and pure 7% Ag-doped ZnO. Tauc's plot also supports the photodegradation results.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.3
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• pp.144-151
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• 2009

Photocatalytic degradation of methylene blue (MB) in aqueous solution was investigated using $TiO_2$ coated on various acid modified activated carbon fiber (ACF). The ACFs/$TiO_2$ composites were prepared from titanium n-butoxide (TNB) as titanium precursor and various acid modified ACFs. The prepared samples are heat treated at 973 K. Then the ACF/$TiO_2$ composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX). Moreover, photocatalytic degradation of MB by the ACF/$TiO_2$ composites was determined under UV irradiation. The results shows that the photocatalytic activity of ACF/$TiO_2$ composites ($AT1{\sim}AT4$) prepared with TNB and various acid modified ACF was much better than that of ACF/$TiO_2$ composite (AT) prepared with TNB and non-acid modified ACF, and the effects improved with order of sample AT3 > AT4 > AT1 > AT2.