• Environmental Engineering Research
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• 제16권2호
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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.

• 한국도로학회논문집
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• 제19권1호
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• pp.53-62
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• 2017

PURPOSES : This research was a fundamental study on the application of an integral $TiO_2$ solution to asphalt concrete pavement. The integral $TiO_2$ solution was produced in pilot production equipment; application of the integral $TiO_2$ solution to asphalt pavement was conducted to examine the pollution-reducing capability of photocatalytic compounds such as $TiO_2$. The photocatalytic $TiO_2$ reacted with air pollutants, converting them into small amounts of relatively benign molecules. METHODS : In this study, laboratory experiments were conducted using five various testing methods. Tensile strength ratio (TSR) and British pendulum test (BPT) were conducted in order to evaluate the properties of asphalt pavement subsequent to the integral $TiO_2$ solution coating. In addition, methylene blue testing, a measurement of nitrate on the coated pavement, and nitrogen oxide (NOx) reduction testing were conducted in order to evaluate photocatalytic reaction. Lastly, a UV-A lamp was used as a light source for photocatalytic reactions. RESULTS : Test results indicated no change in the properties of asphalt pavement following the integral $TiO_2$ solution coating. In order to evaluate the performance of asphalt pavement as a function of $TiO_2$, the moisture susceptibility and skid resistance were investigated. The moisture susceptibility and skid resistance satisfied there quirements related to pavement quality and safety specification. Furthermore, the effects of reduction of air pollution were significantly improved as determined via the methylene blue test and NOx reduction test. The $TiO_2$-paved asphalt specimen exhibited approximately 43% reduction of NOx. CONCLUSIONS : This study has suggested that applying $TiO_2$ rarely impacts asphalt pavement performance measures such as moisture susceptibility and skid resistance, and that its application may be a better means of reducing air pollution. Further studies, such as proper $TiO_2$ dosage rates and compatibility with various pavement types, are required to broaden and generalize its application.

• Bulletin of the Korean Chemical Society
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• 제30권8호
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• pp.1738-1742
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• 2009

Nanocrystalline Zn$Fe_2O_4$ oxide-semiconductor with spinel structure was synthesized by the polymerized complex (PC) method and investigated for its photocatalytic and photoelectric properties. The observation of a highly pure phase and a lower crystallization temperature in Zn$Fe_2O_4$ made by PC method is in total contrast to that was observed in Zn$Fe_2O_4$ prepared by the conventional solid-state reaction (SSR) method. The band gap of the nanocrystalline Zn$Fe_2O_4$ determined by UV-DRS was 1.90 eV (653 nm). The photocatalytic activity of Zn$Fe_2O_4$ prepared by PC method as investigated by the photo-decomposition of isopropyl alcohol (IPA) under visible light (${\geq}$ 420 nm) was much higher than that of the Zn$Fe_2O_4$ prepared by SSR as well as Ti$O_{2-x}N_x$. High photocatalytic activity of Zn$Fe_2O_4$ prepared by PC method was mainly due to its surface area, crystallinity and the dispersity of platinum metal over Zn$Fe_2O_4$.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.54-54
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• 2010

Zinc oxide is metal oxide semiconductor with the 3.37 eV bandgap energy. Zinc oxide is very attractive materials for many application fields. Zinc Oxide has many advantages such as high conductivity and good transmittance in visible region. Also it is cheaper than other semiconductor materials such as indium tin oxide (ITO). Therefore, ZnO is alternative material for ITO. ZnO is attracting attention for its application to transparent conductive oxide (TCO) films, surface acoustic wave (SAW), films bulk acoustic resonator (FBAR), piezoelectric materials, gas-sensing, solar cells and photocatalyst. In this study, we synthesized ZnO nanoparticles and defined their physical and chemical properties. Also we studied about the application of ZnO nanoparticles as a photocatalyst and try to find a enhancement photocatalytic activity of ZnO nanorticles.. We synthesized ZnO nanoparticles using spray-pyrolysis method and defined the physical and optical properties of ZnO nanoparticles in experiment I. When the ZnO are exposed to UV light, reduction and oxidation(REDOX) reaction will occur on the ZnO surface and generate ${O_2}^-$ and OH radicals. These powerful oxidizing agents are proven to be effective in decomposition of the harmful organic materials and convert them into $CO_2$ and $H_2O$. Therefore, we investigated that the photocatalytic activity was increased through the surface modification of synthesized ZnO nanoparticles. In experiment II, we studied on the stability of ZnO nanoparticles in water. It is well known that ZnO is unstable in water in comparison with $TiO_2$. $Zn(OH)_2$ 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 nanoparticles 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 photocatalytic activity changes.

• 멤브레인
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• 제6권2호
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• pp.101-108
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• 1996

반도성 세라믹 광촉매 막 반응기(membrane reactor)에 의한 난분해성 유독 유기물질의 효율적인 분해공정을 개발하기 위한 기초 연구로서 $TiO_{2}$ 광촉매 막의 전기화학 반응에 의한 개미산(formic acid)의 산화/분해 효율성에 대해 연구하였다. 막 반응기는 용액의 여과(filtration)와 광전기화학 반응에 의한 유기물의 광분해를 동시에 수행할 수 있도록 제작되었다. 복합막의 담체임과 동시에 전극의 역할을 할 수 있는 전기 전도성 $SnO_{2}$ 또는 stainless steel 다공성 튜브상에 pH가 1.45인 $TiO_{2}$ 졸을 졸-겔 침지 코팅하여 광촉매 복합막을 제조하였으며 광원으로는 365 nm 파장을 갖는 UV를 사용하였다. $TiO_{2}$ 광촉매 막의 전기화학 반응에 의한 개미산의 산화효율은 전극에 걸어주는 전압과 반응시간에 따라 증가하였으나 투과량(flux)에는 거의 무관하였다. $TiO_{2}/SnO_{2}$ 복합막을 사용한 경우 외부 전압을 27V 걸어주었을때 77% 정도의 산화효율을 얻을 수 있었으며 $TiO_{2}$/stainless steel 복합막에서는 90% 이상이었다. 광촉매 전기화학 반응을 이용함으로써 높은 투과량하에서도 개미산의 산화효율을 단순한 $TiO_{2}$ 광촉매 반응에서 보다 6~7배 가량 증진시킬 수 있었다.

• 센서학회지
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• 제29권2호
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• pp.128-132
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• 2020

Total organic carbon (TOC) analysis equipment, which was previously used to prevent eutrophication in advance, is heavy, bulky, and expensive; therefore, so it is difficult to be carried and has been used as an experimental unit. In this study, a through-carbon analysis chip that integrates pretreatment through photocatalytic oxidation and carbon dioxide measurement using a pH indicator was investigated. Both the total carbon - inorganic carbon method and the nonpurgeable organic carbon (NPOC) measurement method require an acidification part for injecting an acid solution for inorganic carbon measurement and removal, an oxidation part for total carbon or NPOC oxidation and a measurement part for Carbon dioxide (CO₂) measurement. Among them, the measurement of oxidation and CO₂ requires physical technology. The proposed TOC analysis chip decomposed into CO₂ as a result of the oxidizing of organic carbon using a photocatalyst, and the pH indicator that was changed by the generated CO₂ was optically measured. Although the area of the sample of the oxidation part and the pH indicator of the measurement part were distinguished in an enclosed space, CO₂ was quantified by producing an oxidation part and a measurement part that shared the same air in one chip. The proposed TOC analysis chip is less expensive and smaller, cost and size are disadvantages of existing organic carbon analysis equipment, because it does not require a separate carrier gas to transport the CO₂ gas in the oxidation part to the measurement part.

• 한국재료학회지
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• 제29권12호
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• pp.790-797
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• 2019

To improve photocatalytic performance, CdS nanoparticle deposited TiO₂ nanotubular photocatalysts are synthesized. The TiO₂ nanotube is fabricated by electrochemical anodization at a constant voltage of 60 V, and annealed at 500 for crystallization. The CdS nanoparticles on TiO₂ nanotubes are synthesized by successive ionic layer adsorption and reaction method. The surface characteristics and photocurrent responses of TNT/CdS photocatalysts are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis spectrometer and LED light source installed potentiostat. The bandgaps of the CdS deposited TiO₂ photocatalysts are gradually narrowed with increasing of amounts of deposited CdS nanoparticles, which enhances visible light absorption ability of composite photocatalysts. Enhanced photoelectrochemical performance is observed in the nanocomposite TiO₂ photocatalyst. However, the maximum photocurrent response and dye degradation efficiency are observed for TNT/CdS30 photocatalyst. The excellent photocatalytic performance of TNT/CdS30 catalyst can be ascribed to the synergistic effects of its better absorption ability of visible light region and efficient charge transport process.

• 한국세라믹학회지
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• 제39권6호
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• pp.535-539
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• 2002

이 연구는 저온균일침전법으로 제조한 루타일 상의 TiO$_2$ 나노분말을 이용하여 AgNO$_3$ 수용액 중에서 광반응 조건에 따른 Ag 이온의 광흡차 특성을 고찰하였다. 자연광을 조사하였을 경우 흡척되는 Ag의 양이 9.32ppm이며 Ag 이온의 환원 속도는 느리지만 루타일 TiO$_2$ 나노분말이 자연광에서도 광촉매 반응을 일으킨다는 것을 확인하였다. 암반응 하에서도 TiO$_2$ 나노분말 자체의 밤송이 형태 때문에 Ag흡착 반응이 진행되었으며, UV를 적용할 때에는 120분 이내에 Ag 이온이 전부 흡착되었다. 광촉매 반응이 더 중요시 됨을 알수 있었다. 흡착 반응속도상수와 흡착 평형속도상수를 계산한 결과, 각각 0.0004g/min와 1494.20(120 $m^2$/g)를 나타내었다.

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2004-2008
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• 2014

This paper reports the facile synthesis methods of zinc oxide (ZnO) nanoparticles, Z1-Z10, using diethylene glycol (DEG) and polyethylene glycol (PEG400). The particle size and morphology were correlated with the PEG concentration and reaction time. With 0.75 mL of PEG400 in 150 mL of DEG and a 20 h reaction time, the ZnO nanoparticles began to disperse from a collective spherical grain shape. The ZnO nanoparticles were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and a $N_2$ adsorption-desorption studies. The Brunauer-Emmett-Teller (BET) surface areas of Z4, Z5 and Z10 were 157.083, 141.559 and 233.249 $m^2/g$, respectively. The observed pore diameters of Z4, Z5 and Z10 were 63.4, 42.0 and 134.0 ${\AA}$, respectively. The pore volumes of Z4, Z5 and Z10 were 0.249, 0.148 and 0.781 $cm^3/g$, respectively. The photocatalytic activity of the synthesized ZnO nanoparticles was evaluated by methylene blue (MB) degradation, and the activity showed a good correlation with the $N_2$ adsorption-desorption data.

• 공업화학
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• 제23권3호
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• pp.308-312
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• 2012

암모니아를 이용하여 질소가 도핑된 광촉매를 제조하고 이에 따른 가시광 광촉매 활성효과를 알아보았다. 질소 도핑된 $TiO_2$ 광촉매가 태양광영역에서 분해되는 정도를 확인하기 위해서 태양광에 조사하에 메틸렌블루 염료분해 실험을 수행하였다. SEM 이미지 분석결과 질소가 도핑된 $TiO_2$ 광촉매의 응집 입자가 감소함을 알 수 있었고, XRD 결과 $600^{\circ}C$에서 열처리된 질소 도핑 $TiO_2$ 광촉매는 아나타제 구조와 루타일이 존재하고 있음을 알 수 있었다. 또한, X선 광전자 분광기 분석을 통하여 암모니아 반응시간에 따라서 $TiO_2$ 광촉매에 N의 조성 증가를 알 수 있었다. $TiO_2$ 광촉매의 질소 도핑에 의하여 메틸렌블루에 대한 광분해 효과가 도핑되지 않은 시료에 비해 증가하였다. 또한 질소 도핑은 $TiO_2$ 광촉매의 결정에도 영향을 주었다.