• 제목/요약/키워드: $WO_3$ photocatalysts

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기상 불소화법을 이용한 WO3-xFx 광촉매의 합성 및 광분해 특성 (Synthesis and Photocatalytic Activity of WO3-xFx Photocatalysts Using a Vapor Phase Fluorination)

  • 이혜련;임채훈;이란은;이영석
    • 공업화학
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    • 제32권6호
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    • pp.632-639
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    • 2021
  • 본 연구에서는 WO3 광촉매의 활성을 증대시키기 위하여 불소 도핑을 수행하고, 메틸렌블루 염료를 이용하여 광분해 특성을 고찰하였다. 본 연구를 통해 제조된 WO3-xFx 광촉매는 WCl6 전구체로부터 WO3 광촉매를 제조하기 위한 소결과정 중에 기상 불소화 방법을 이용하여 제조하였다. 불소 도핑 후 WO3 광촉매의 밴드갭이 2.95 eV에서 2.54 eV로 감소하였고, 산소 결핍 자리 영역이 약 55% 증가하였다. 또한 제조한 광촉매의 초기 염료 분해 성능은 불소 도핑 전과 비교하였을 때 10%에서 60%로 불소 도핑 후 6배 증가하였다. 이는 불소가 도핑되어 광촉매의 밴드갭이 감소하여 적은 에너지로 촉매 활성 반응을 가능하게 하고, 또한 산소 결핍이 생성된 표면 결함이 WO3 광촉매의 가시광선 흡수영역을 증대시켜 광촉매 활성이 증가한 것으로 사료된다. 본 연구에서는 후처리 공정이 불필요한 원스텝 기상 불소화 반응을 이용하여 손쉬운 방법으로 광촉매활성이 뛰어난 불소가 도핑된 WO3-xFx 광촉매를 제조할 수 있음을 확인하였다.

플라즈마 및 직접 기상 불소화에 의해 제어된 산소결핍 불소화 WO3 광촉매의 광분해 특성 (Photodegradation Characteristics of Oxygen Vacancy-fluorinated WO3 Photocatalysts Controlled by Plasma and Direct Vapor Fluorination)

  • 이혜련;이란은;김대섭;이영석
    • 공업화학
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    • 제33권2호
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    • pp.159-165
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    • 2022
  • WO3 광촉매의 광분해 성능을 증대시키기 위하여 산소결핍자리 생성을 유도하기 위한 불소 도핑을 수행하였다. 불소 도핑을 위하여 플라즈마 불소화와 직접 기상 불소화를 진행하였으며, 두 가지 방법으로 불소화한 WO3 광촉매의 광분해 성능을 비교하기 위하여 메틸렌블루 염료 분해 성능을 평가하였다. 플라즈마 불소화한 WO3 광촉매와 직접 기상 불소화한 WO3 광촉매의 산소결핍자리는 각 14.65 및 18.59%로 미처리 WO3 광촉매 대비 각 23, 56% 증가하였으며, WO3 광촉매의 산소결핍자리가 증가함에 따라 메틸렌블루 염료분해 성능 역시 미처리 WO3 광촉매 대비 각 1.7, 3.4배 증가한 것을 확인하였다. 또한 불소 도핑 후 밴드갭 에너지는 각 2.95 eV에서 2.64, 2.45 eV로 감소한 것을 확인하였다. 이러한 결과로 미루어 보아 직접 기상 불소화 공정이 플라즈마 불소화 공정과 비교하여 WO3 광촉매의 활성을 증대시키는데 유리한 공정인 것으로 사료된다.

티타늄 함유 텅스텐 산화물 광촉매를 이용한 메탄올/물 분해로부터 수소제조 (Hydrogen Production from Photocatalytic Splitting of Methanol/water Solution over Ti Impregnated WO3)

  • 이가영;박유진;박노국;이태진;강미숙
    • 청정기술
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    • 제18권4호
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    • pp.355-359
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    • 2012
  • 본 연구에서는 보다 효율적인 광 전기화학적 수소제조를 위하여 광촉매로써 산화텅스텐에 티타늄을 함침하여 $Ti/WO_3$ 나노입자를 제조하였다. 제조한 $Ti/WO_3$의 물리적 특성은 X-선 회절분석법(XRD), 주사전자현미경(SEM), 발광분광계(PL), 원자간력 현미경(AFM), 정전기 현미경(EFM)을 통해 확인하였다. 메탄올/물 (1/1) 광분해 수소제조 실험 결과, 순수 아나타제 티타니아나 산화텅스텐 광촉매보다 $Ti/WO_3$ 광촉매에서 촉매활성이 향상되었으며, 0.5 g의 0.10 mol % $Ti/WO_3$ 촉매를 사용한 경우 8시간 반응 시 3.02 mL의 수소가 발생되었다.

Rhodomine B dye removal and inhibitory effect on B. subtilis and S. aureus by WOx nanoparticles

  • Ying, Yuet Lee;Pung, Swee Yong;Ong, Ming Thong;Pung, Yuh Fen
    • Journal of Industrial and Engineering Chemistry
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    • 제67권
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    • pp.437-447
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    • 2018
  • Visible-light-driven wide bandgap semiconductor photocatalysts were commonly developed via doping or coupling with another narrow bandgap metal oxide. However, these approaches required extra processing. The aim of study was to evaluate the photocatalytic performance of narrow bandgap $WO_x$ nanoparticles. A mixture of $WO_2$ and $WO_3$ nanoparticles were synthesized using solution precipitation technique. The photodegradation of RhB by these nanoparticles more effective in UV light than in visible light. In antibacterial susceptibility assay, $WO_x$ nanoparticles demonstrated good antibacterial against Gram-positive bacteria. The cell wall of bacterial was the main determinant in antibacterial effect other than $W^{4+}/W^{6+}$ ions and ROS.

Sonocatalytic Degradation of Rhodamine B in the Presence of TiO2 Nanoparticles by Loading WO3

  • Meng, Ze-Da;Sarkar, Sourav;Zhu, Lei;Ullah, Kefayat;Ye, Shu;Oh, Won-Chun
    • 한국재료학회지
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    • 제24권1호
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    • pp.6-12
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    • 2014
  • In the present work, $WO_3$ and $WO_3-TiO_2$ were prepared by the chemical deposition method. Structural variations, surface state and elemental compositions were investigated for preparation of $WO_3-TiO_2$ sonocatalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) were employed for characterization of these new photocatalysts. A rhodamine B (Rh.B) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an Rh.B solution was observed using the $WO_3-TiO_2$ composites under ultrasonic irradiation. Sonocatalytic degradation is a novel technology of treating wastewater. During the ultrasonic treatment of aqueous solutions sonoluminescence, cavitaties and "hot spot" occurred, leading to the dissociation of water molecules. In case of a $WO_3$ coupled system, a semiconductor coupled with two components has a beneficial role in improving charge separation and enhancing $TiO_2$ response to ultrasonic radiations. In case of the addition of $WO_3$ as new matter, the excited electrons from the $WO_3$ particles are quickly transferred to $TiO_2$ particle, as the conduction band of $WO_3$ is 0.74 eV which is -0.5 eV more than that of $TiO_2$. This transfer of charge should enhance the oxidation of the adsorbed organic substrate. The result shows that the photocatalytic performance of $TiO_2$ nanoparticles was improved by loading $WO_3$.

볼밀을 이용한 TiO2/WO3 복합체 제조 및 광촉매 특성 (Photocatalysis of TiO2/WO3 Composites Synthesized by Ball Milling)

  • 유수열;남충희
    • 한국분말재료학회지
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    • 제25권4호
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    • pp.316-321
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    • 2018
  • Composites of P25 $TiO_2$ and hexagonal $WO_3$ nanorods are synthesized through ball-milling in order to study photocatalytic properties. Various composites of $TiO_2/WO_3$ are prepared by controlling the weight percentages (wt%) of $WO_3$, in the range of 1-30 wt%, and milling time to investigate the effects of the composition ratio on the photocatalytic properties. Scanning electron microscopy, x-ray diffraction, and transmission electron microscopy are performed to characterize the structure, shape and size of the synthesized composites of $TiO_2/WO_3$. Methylene blue is used as a test dye to analyze the photocatalytic properties of the synthesized composite material. The photocatalytic activity shows that the decomposition efficiency of the dye due to the photocatalytic effect is the highest in the $TiO_2/WO_3$ (3 wt%) composite, and the catalytic efficiency decreases sharply when the amount of $WO_3$ is further increased. As the amount of $WO_3$ added increases, dye-removal by adsorption occurs during centrifugation, instead of the decomposition of dyes by photocatalysts. Finally, $TiO_2/WO_3$ (3 wt%) composites are synthesized with various milling times. Experimental results show that the milling time has the best catalytic efficiency at 30 min, after which it gradually decreases. There is no significant change after 1 hour.

가시광 활성 WO3-TiO2 복합체 광촉매의 제조 및 이의 특성 평가 (Preparation of WO3-TiO2 Photocatalyst and Evaluation of Its Photo-activity in the Visible Light Range)

  • 여인철;강인철
    • 한국분말재료학회지
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    • 제20권6호
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    • pp.474-478
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    • 2013
  • The most general photocatalyst, $TiO_2$ and $WO_3$, are acknowledged to be ineffective in range of visible light. Therefore, many efforts have been directed at improving their activity such as: band-gap narrowing with non-metal element doping and making composites with high specific surface area to effectively separate electrons and holes. In this paper, the method was introduced to prepare a photo-active catalyst to visible irradiation by making a mixture with $TiO_2$ and $WO_3$. In the $TiO_2-WO_3$ composite, $WO_3$ absorbs visible light creating excited electrons and holes while some of the excited electrons move to $TiO_2$ and the holes remain in $WO_3$. This charge separation reduces electron-hole recombination resulting in an enhancement of photocatalytic activity. Added Ag plays the role of electron acceptor, retarding the recombination rate of excited electrons and holes. In making a mixture of $TiO_2-WO_3$ composite, the mixing route affects the photocatalytic activity. The planetary ball-mill method is more effective than magnetic stirring route, owing to a more effective dispersion of aggregated powders. The volume ratio of $TiO_2(4)$ and $WO_3(6)$ shows the most effective photocatalytic activity in the range of visible light in the view point of effective separation of electrons and holes.

A facile one-pot solution-phase route to synthesizing anovel composite hierarchical hollow structure: W18O49/WO2 Hollow Nanourchins

  • 전성호;용기중
    • 한국재료학회:학술대회논문집
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    • 한국재료학회 2009년도 추계학술발표대회
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    • pp.33.1-33.1
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    • 2009
  • To date, nanostructured tungsten oxides with a variety of stoichiometries, such as WO3, WO2.9, W18O49, and WO2, have been prepared, because they are promising candidates for applications such as gas sensors, photocatalysts, electrochromic devices, and field emission devices. Among them, W18O49 and WO2 have been widely studied due to their outstanding chemical sensing, catalytic, and electron emissive properties. Here we report, for the first time, a one-pot solution-phase route to synthesizing a novel composite hierarchical hollow structure without adding catalysts, surfactants, or templates. The products, consisting of a WO2 hollow core sphere surrounded by a W18O49 nanorod shell (yielding a sea urchin-like structure), were generated as discrete structures via Ostwald ripening. To our knowledge, this type of composite hierarchical core/shell structure has not been reported previously. The morphological evolution and the detailed growth mechanism were carefully studied. We also demonstrate that the size of the hollow urchins is readily tunable by controlling the reactant concentrations.Interestingly, although bulk tungsten oxides are weakly paramagnetic or diamagnetic, the as-prepared products show unusual ferromagnetic behavior atroom temperature. The urchin structures also show a very high Brunauer-Emmet-Teller (BET) surface area, suggesting that they may potentially be applied to chemical sensor or effective catalyst technologies.

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Synthesis of Bi2WO6 Nanometer Sheet Shaped and Approach to the Photocatalysis

  • Kim, Dong-Young;Kim, Su-Jung;Kang, Mi-Sook
    • Bulletin of the Korean Chemical Society
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    • 제30권3호
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    • pp.630-635
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    • 2009
  • For use as a photocatalyst, bismuth tungsten oxide, $Bi_2WO_6$, was successfully synthesized by hydrothermal treatment at pH = 11 and heating at 200 ${^{\circ}C}$ for 24h, and samples were subsequently thermal treated at 400, 600, and 800 ${^{\circ}C}$ to increase crystallinity. TEM results revealed that the initial untreated particles were sheet‐shaped, grain size was below 80 nm, and it increased with treated temperatures. These $Bi_2WO_6$ samples absorbed at around 400 nm in the visible light range and the intensity of absorption was particularly strongest in samples thermal treated at 600 ${^{\circ}C}$. Their photoluminescence abilities, related to the recombination between the excited electrons and holes, were overall small for other general photocatalysts such as TiO2, and the smallest in the case of thermal treatment at 600 ${^{\circ}C}$, as reversible result of UV‐visible absorbance. Methyl orange of 5.0 ppm aqueous solution was almost completely removed after 2 h when treated over the $Bi_2WO_6$ thermal treated at 600 ${^{\circ}C}$.

수소생산을 위한 물 분해용 광전극에 도입된 환원된 산화그래핀이 광전기화학성능에 미치는 영향 (Effect of Reduced Graphene Oxide in Photoanode on Photoelectrochemical Performance in Water Splitting for Hydrogen Production)

  • 윤상혁;딩진루이;김교선
    • 한국수소및신에너지학회논문집
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    • 제27권4호
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    • pp.329-334
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    • 2016
  • Hydrogen is eco-friendly alternative energy source and the photoelectrochemical water splitting is believed to be one of the promising methods for hydrogen production. Many researchers have studied several potential photocatalysts to increase the photoelectochemical performance efficiency for hydrogen conversion. In this study, the GO (graphene oxide) was prepared by Tour's method and was dispersed in precursor solutions of $WO_3$ and $BiVO_4$. Those precursor solutions were spin-coated on FTO glass and several photocatalyst thin films of $WO_3$, $BiVO_4$ and $WO_3/BiVO_4$ were prepared by calcination. The morphologies of prepared photocatalyst thin films were measured by scanning electron microscope. The photoelectrochemical performances of photocatalyst thin films with rGO (reduced graphene oxide) and without rGO were analyzed systematically.