• Title/Summary/Keyword: Photocatalysts

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Preparation and Characterization and Visible Light Photocatalytic Activity of Fe-Treated AC/TiO2 Composites for Methylene Blue

  • Meng, Za-Da;Zhang, Kan;Oh, Won-Chun
    • 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.

Design of Nanocomposite Photocatalysts for Solar Hydrogen Production (광화학적 수소제조를 위한 나노복합 광촉매의 설계)

  • Jang, Jum Suk;Kim, Hyun Gyu;Lee, Jae Sung
    • Korean Chemical Engineering Research
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    • v.45 no.5
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    • pp.415-423
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    • 2007
  • Photocatalytic water splitting (PWS) is the most promising technology to produce $H_2$ energy directly from renewable water and solar light. In spite of the remarkable progress made in the last decade, there are still many technical challenges remaining particularly in finding new photocatalytic materials with high efficiency and durability. This article discusses the application of nanocomposite materials in search of new photocatalytic materials for solar hydrogen production from water. It has been demonstrated that smart combination and modification of known materials and functions could be fruitful approach for the purpose.

Photocatalytic Degradation of Dibenzothiophene in Aqueous Phase (수중 Dibenzothiophene의 광촉매 분해에 관한 연구)

  • Jo, Sung-Hye;Yoe, Seok-Jun;Kim, Il-Kyu
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.4
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    • pp.527-534
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    • 2011
  • In this research, the photocatalytic degradation of dibenzothiophene (DBT) in $TiO_2$ aqueous suspension has been studied. $TiO_2$ photocatalysts are prepared by a sol-gel method. The dominant anatase-structure on $TiO_2$ particles is observed after calcining the $TiO_2$ gel at $500^{\circ}C$ for 1hr. Photocatalysts with various transition metals (Nd, Pd and Pt) loading are tested to evaluate the effect of transition metal impurities on photodegradation. The photodegradation efficiencies with $TiO_2$ including Pt and Pd are higher than pure $TiO_2$ powder. Also we investigated the applicability of $H_2O_2$ to increase the efficiency of the $TiO_2$ photocatalytic degradation of dibenzothiophene. The degradation efficiency increases with increasing dosage of $H_2O_2$ in the range of 0.01M to 0.1M . The effect of pH is investigated; we obtained the maximum photodegradation efficiency at pH 5. In addition, the intermediate analysis found dihydroxyl -dibenzothiophene as a reaction intermediate of dibenzothiophene during the photodegradation.

Photocatalytic Degradation of Trichloroethylene in Aqueous Phase (수중 Trichloroethylenel의 광촉매 분해특성에 관한 연구)

  • Jo, Sung-Hye;Nam, Ju-Hee;Kim, Il-Kyu
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.4
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    • pp.555-564
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    • 2011
  • The photocatalytic degradation of trichloroethylene (TCE) in $TiO_2$ aqueous suspension has been studied. $TiO_2$ photocatalysts are prepared by a sol-gel method. The dominant anatase-structure on $TiO_2$ particles is observed after calcining the $TiO_2$ get at $500^{\circ}C$ for 1hr. The Langmuir-Hinshelwood model is applicable to describe the photodegradation, which indicates that adsorptionof the solute on the surface of $TiO_2$ particles plays an important role in photodegradation. Photocatalysts with various transition metals (Nd, Pd and Pt) loading are tested to evaluate the effect of transition metal impurities on photodegradation. The photodegradation efficiencies with $TiO_2$ including Pt, Pd and Nd are lower than pure $TiO_2$ powder. The effect of pH is investigated and the maximum photodegradation efficiency is obtained at pH 7. In addition, the intermediates such as dichloromethane, chloroform, and trichloroethane are detected during the photodegradation of TCE.

High Photocatalytic Activity of Gd2O2S:Tb Modified Titanium Dioxide Films

  • Kim, Bum-Goo;Lee, Hak-Guen;Kim, Hee-Sung;Kim, Young-Soon
    • Bulletin of the Korean Chemical Society
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    • v.30 no.3
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    • pp.675-678
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    • 2009
  • $Fe_2O_3,\;Ag_2O,\;CaWO_4$ and $Gd_2O_2S$:Tb loaded on titanium dioxide photocatalysts (P25, Degussa) were prepared by a calcination. Their composite films containing water-born polyurethane used as a material for immobilization were obtained by spray coating technique. The photocatalytic activity of the titanium dioxide films was characterized by decrease of UV-vis absorption spectra for methylene blue and gas chromatography for photocatalytic decomposition of formaldehyde diluted in water. It was shown that the $Gd_2O_2S$:Tb modified titanium dioxide films had good photocatalytic properties and followed the first-order kinetic model with regard to photocatalytic decoloration of methylene blue. Especially in formaldehyde photodegradation experiment, decrease rate of concentration of the titanium dioxide films with $Gd_2O_2S$:Tb modifying was about 35% larger than that of the unloaded titanium dioxide film.

Degradation of a Refractory Organic Contaminant by Photocatalytic Systems

  • Kim, Il-Kyu
    • Journal of Power System Engineering
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    • v.18 no.6
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    • pp.133-139
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    • 2014
  • In this research, the photocatalytic degradation of benzothiophene in $TiO_2$ aqueous suspension has been studied. $TiO_2$ photocatalysts are prepared by a sol-gel method. The dominant anatase-structure on $TiO_2$ particles is observed after calcining the $TiO_2$ gel at $500^{\circ}C$ for 1hr. Photocatalysts with various transition metals (Nd, Pd and Pt) loading are tested to evaluate the effect of transition metal impurities on photodegradation. The photocatalytic degradation in most cases follows first-order kinetics. The maximum photodegradation efficiency is obtained with $TiO_2$ dosage of 0.4g/L. The photodegradation efficiency with Pt-$TiO_2$ is higher than pure $TiO_2$ powder. The optimal content value of Pt is 0.5wt.%. Also we investigate the applicability of $H_2O_2$ to increase the efficiency of the $TiO_2$ photocatalytic degradation of benzothiophene. The optimal concentration of $H_2O_2$ is 0.05. The effect of pH is investigated; we obtain the maximum photodegradation efficiency at pH 9. Hydroxy-benzothiophenes and dihydroxy-benzothiophenes are identified as reaction intermediates. It is proposed that benzothiophene is oxidized by OH radical to sequentially form hydroxyl-benzothiophenes, dihydroxybenzothiophenes, and benzothiophenedione.

Photocatalytic Degradation of Organic Compounds over $xTiO_2$-$ySiO_2$ Powders Prepared by Sol-Gel Method (졸-겔법으로 제조된 $xTiO_2$-$ySiO_2$ 분말에 의한 유기물의 광분해)

  • Yang, Chun-Hoe;Lee, Bong-Cheol
    • Journal of the Korean Applied Science and Technology
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    • v.25 no.2
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    • pp.130-136
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    • 2008
  • $xTiO_2$-$ySiO_2$ system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area were measured. Considering the efficiency of the ethanol and phenol degradation using the catalyst, the conclusions were obtained as follows: By means of X-ray analysis of $xTiO_2$-$ySiO_2$ powder that is obtained from Titanium and Silicon alkoxide by sol-gel process, it is shown that crystal structure of anatase type is a dominating structure and, on the other hand, the structure of rutile also partly exists. The increase of $SiO_2$ contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. It is shown that more than 90% of ethanol and phenol are degraded when reaction time is about three and an hours, and the maximum degradation rate of ethanol and phenol is shown in $60TiO_2$-$40SiO_2$ catalyst.

Synthesis and Characterization of Fe-fullerene/TiO2 Photocatalysts Designed for Degradation of Methylene Blue

  • Meng, Za-Da;Zhang, Kan;Oh, Won-Chun
    • Korean Journal of Metals and Materials
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    • v.48 no.7
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    • pp.674-682
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    • 2010
  • Fe-fullerene/$TiO_2$ composite photocatalysts were prepared with titanium (IV) n-butoxide (TNB) by a sol-gel method. The samples were characterized by scanning electron microscopy (SEM), Transmission electron microscope (TEM), specific surface area (BET), X-ray diffraction analysis (XRD) and energy dispersive X-ray spectroscopy (EDX). The photocatalytic activities were evaluated by the photocatalytic degradation of methylene blue (MB) solution. XRD patterns of the composites showed that the Fe-fullerene/$TiO_2$ composite contained a typical single and clear anatase phase. The surface properties shown by SEM present a characterization of the texture on Fe-fullerene/$TiO_2$ composites and showed a homogenous composition in the particles for the titanium sources used. The EDX spectra for the elemental identification showed the presence of C and Ti with strong Fe peaks for the Fe-fullerene/$TiO_2$ composite. From the photocatalytic results, the excellent activity of the Fe-fullerene/$TiO_2$ composites for degradation of methylene blue under UV light irradiation could be attributed to both the effects between photocatalytic reaction of the supported $TiO_2$, decomposition of the organometallic reaction by the Fe compound and energy transfer effects such as electron and light of the fullerene.

Fabrication of Ag/In2O3/TiO2/HNTs hybrid-structured and plasma effect photocatalysts for enhanced charges transfer and photocatalytic activity

  • Wang, Huiqin;Wu, Dongyao;Liu, Chongyang;Guan, Jingru;Li, Jinze;Huo, Pengwei;Liu, Xinlin;Wang, Qian;Yan, Yongsheng
    • Journal of Industrial and Engineering Chemistry
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    • v.67
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    • pp.164-174
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    • 2018
  • The purpose of this work designed hybrid-structured and plasma effect photocatalyst of $Ag/In_2O_3/TiO_2/HNTs$ via sol-gel and photo-reduction methods. The structures, morphologies, optical and photoelectric performances of as-prepared photocatalysts were characterized via XRD, TEM, XPS, BET, UV-vis DRS, PL and photocurrents. The photocatalytic activity was evaluated by degradation of TC. The results showed that the hybrid-structure and plasma effect can effectively cause the multi-transfer of electrons and increase the separation rate of electron and hole pairs which obtained high photocatalytic activity. The photocatalytic degradation processes reveal that $^{\bullet}O_2{^-}$ and $h^+$ are major active species.

Photo-Electrochemical Hydrogen Production Over P- and B- Incorporated $TiO_2$ Nanometer Sized Photo-Catalysts (P와 B 이온이 함유된 나노 티타니아 광촉매의 광 전기화학적 수소 제조 성능)

  • Kwak, Byeong-Sub;Choi, Hee-Chan;Woo, Jae-Wook;Lee, Ju-Seung;An, June-Bum;Ryu, Si-Gyeong;Kang, Mi-Sook
    • Clean Technology
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    • v.17 no.1
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    • pp.78-82
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    • 2011
  • For effectively photochemical hydrogen production, P (negative semiconductor) and B (positive semiconductor) ions (0.1, 0.2, 0.5, and 1.0 mol%) incorporated $TiO_2$ (P- and B-$TiO_2$) nanometer sized particles were prepared using a solvothermal method as a photocatalyst. The characteristics of the synthesized P- and B-$TiO_2$ photocatalysts were analyzed by X-ray Diffraction (XRD), Transmission electron microscopy (TEM), W-visible spectroscopy (UV-Vis), and Photoluminescence spectra (PL). The evolution of $H_2$ from methanol/water (1:1) photo-splitting over B-$TiO_2$ photocatalysts was enhanced compared to those over pure $TiO_2$ and P-$TiO_2$ photocatalysts; 0.42 mL of $H_2$ gas was evolved after 10 h when 0.5 g of a 1.0 mol% B-$TiO_2$ catalyst was used.