• Title, Summary, Keyword: gold catalyst

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Synthesis of Gold Nanoparticles Using Fullerene Oxide and Their Catalytic Activity for Reduction of 4-Nitroaniline

  • Park, Geun Wook;Ko, Jeong Won;Ko, Weon Bae
    • Elastomers and Composites
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    • v.54 no.2
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    • pp.105-109
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    • 2019
  • Gold nanoparticles were synthesized by reacting potassium tetrachloroaurate ($KAuCl_4$), potassium carbonate ($K_2CO_3$), and isopropyl alcohol in the presence of fullerene oxide [$C_{60}(O)_n$, $n{\geq}1$], which was, in turn, prepared from [$C_{60}$] fullerene and m-chloroperoxybenzoic acid under refluxing conditions. The crystallinity and morphology of the prepared gold nanoparticles were confirmed by UV-vis spectroscopy, X-ray diffraction, and scanning electron microscopy. The activity of the gold nanoparticles in the reduction of 4-nitroaniline was measured in order to determine its capability as a catalyst.

Study on the Partial Hydrogenation of Butadiene over Highly Dispersed Supported Gold Catalysts (고분산 담지 금 촉매에 의한 Butadiene의 부분 수소화에 관한 연구)

  • Ahn, Ho-Geun;Hiroo, Niiyama
    • Applied Chemistry for Engineering
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    • v.10 no.7
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    • pp.1003-1007
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    • 1999
  • The activity and products distribution for the hydrogenation of butadiene and pentadiene over the gold and cobalt catalysts prepared by coprecipitation and impregnation method was investigated with using a flow reactor under atmospheric pressure. The reaction characteristics of the highly dispersed gold particles and its role were studied. The activity of the gold catalyst by coprecipitation was much higher than that by impregnation. The selectivity of butene on all gold particles was always 100% even in the absence of butadiene in the stream, but butadiene on cobalt supported catalyst was easily hydrogenated to butane. It was therefore considered that the active sites at circumferences of the gold particles possessed an unique property which took a proper affinity to hydrogen. In the hydrogenation of butadiene and pentadiene, the percentages of 1-butene and 2-pentene were 60%~70% and about 62%, respectively. The results could be simply explained by a statistical concepts of hydrogen addition.

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Preparation of Nanosized Gold Particles by Microwave Irradiation and Kinetics Study for Reduction of 4-Nitroaniline under Various Conditions

  • Kim, Jae Jin;Ko, Weon Bae
    • Elastomers and Composites
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    • v.50 no.4
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    • pp.274-278
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    • 2015
  • Nanosized gold particles were synthesized by microwave irradiation in a mixture composed of potassium tetrachloroaurate(III) n-hydrate, sodium citrate dihydrate and Tween 20. The synthesized gold particles were characterized by UV-vis spectrophotometer, scanning electron microscopy, and X-ray diffraction techniques. Using UV-vis spectroscopy, it was confirmed that gold nanoparticles act as a catalyst in the reduction of 4-nitroaniline with sodium borohydride to form 1,4-diaminobenzene. Additionally, we studied the kinetics of this reductive reaction in the presence of these gold nanoparticles under various conditions.

Highly Dispersed Supported Gold Catalysts -I. Effect of Gold Addition and Active Site Formation- (고분산 담지 금촉매 - I. 금의 첨가 효과 및 활성점 생성 -)

  • Ahn, Ho-Geun;Niiyama, Hiroo
    • Applied Chemistry for Engineering
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    • v.5 no.2
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    • pp.285-294
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    • 1994
  • Some supported gold catalysts were prepared by impregnation and coprecipitation methods. Effect of gold addition and active sloe formation were studied by investigating particle sizes of gold, amounts of oxygen adsorbed, adsorption properties of CO and NO, and reduction and oxidation properties, etc.. The gold particles of the catalyst by impregnation were irregular and very large as 30~100 nm, but those by coprecipitation were uniform and ultra-fine as about 4 nm. On $Au/Al_2O_3$ catalyst, the addition of gold to inactive $Al_2O_3$ caused the decomposition of $N_2O$, and CO was not irreversibly adsorbed while $O_2$ was atomically and irreversibly adsorbed. The adsorption sites of oxygen were attributed to the active sites which were restricted to the circumference of hemispherical gold particle-support interface rather than all atoms on the surface of gold particle. Also, CO was reversibly and irreversibly adsorbed on $Al_2O_3$ at low temperature, and the addition of gold weakened both reversible and irreversible adsorptions. The affinity for CO on $Au/Co_3O_4$ catalyst decreased conspicuously compared to $Co_3O_4$. The effect of gold addition did not appear in reduction step but did remarkably in reoxidation step; the added gold promoted the reoxidation of the reduced cobalt atoms.

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Functional Gold Nanoparticles (기능성 금 나노입자)

  • Lee, Jun-Wung
    • Journal of the Korea Institute of Military Science and Technology
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    • v.12 no.6
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    • pp.739-749
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    • 2009
  • Ever since gold was found, this element has fascinated human beings. It is stable in air, and is illuminating for several thousands years without changing its colors. Nanoparticles are the basic nanommaterials, and, particularly gold nanoparticles show unique properties which are not shown in bulk states. Scientists are trying to apply these new properties to catalysts, bioscience, optics, etc. Judging from the current research activities, one can envisage that gold nanoparticles can play a major role in opening a new era in diagnoses and treatment of diseases like cancers. However to apply the nanoparticles one must modify the surface of the nanoparticles in order to give the materials certain functionalities. It certainly is worth to review the current research status and challenges in the area of functional gold nanoparticles.

Electrochemistry on Alternate Structures of Gold Nanoparticles and Ferrocene-Tethered Polyamidoamine Dendrimers

  • Suk, Jung-Don;Lee, Joo-Han;Kwak, Ju-Hyoun
    • Bulletin of the Korean Chemical Society
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    • v.25 no.11
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    • pp.1681-1686
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    • 2004
  • Self-assembled systems with polyamidoamine (PAMAM) dendrimers combined with gold nanoparticles have been widely studied because of their potential applications in molecular electronics, catalyst carriers, chemical sensors, and biomedical devices. In our work, gold nanoparticle monolayers and multilayers with pure and ferrocene-tethered PAMAM dendrimers as cross-linking molecules were deposited on a mixed self-assembled monolayer of gold substrates. The various generations of PAMAM dendrimers can be covalently attached to mercaptoundecanoic acid mixed with a mercaptoundecanol self-assembled monolayer. Cyclic voltammograms show that redox peak currents on the alternate multilayers of gold nanoparticles and ferrocene-tethered PAMAM dendrimers increase as the number of layers increases. Fourier transform IR external reflection spectroscopy and scanning electron microscopy support the results from electrochemical measurements.

Free-standing Three Dimensional Graphene Incorporated with Gold Nanoparticles as Novel Binder-free Electrochemical Sensor for Enhanced Glucose Detection

  • Bui, Quoc Bao;Nguyen, Dang Mao;Nguyen, Thi Mai Loan;Lee, Ku Kwac;Kim, Hong Gun;Ko, Sang Cheol;Jeong, Hun
    • Journal of Electrochemical Science and Technology
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    • v.9 no.3
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    • pp.229-237
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    • 2018
  • The electrochemical sensing performance of metal-graphene hybrid based sensor may be significantly decreased due to the dissolution and aggregation of metal catalyst during operation. For the first time, we developed a novel large-area high quality three dimensional graphene foam-incorporated gold nanoparticles (3D-GF@Au) via chemical vapor deposition method and employed as free-standing electrocatalysis for non-enzymatic electrochemical glucose detection. 3D-GF@Au based sensor is capable to detect glucose with a wide linear detection range of $2.5{\mu}M$ to 11.6 mM, remarkable low detection limit of $1{\mu}M$, high selectivity, and good stability. This was resulted from enhanced electrochemical active sites and charge transfer possibility due to the stable and uniform distribution of Au NPs along with the enhanced interactions between Au and GF. The obtained results indicated that 3D-GF@Au hybrid can be expected as a high quality candidate for non-enzymatic glucose sensor application.

Effect of Water Addition on Activity of Gold Catalysts Supported on Metal Oxide at Low Temperature CO Oxidation (일산화탄소 저온 산화에서 금속산화물에 담지된 금촉매의 활성에 미치는 수분첨가의 영향)

  • Ahn, Ho-Geun;Kim, Ki-Joong;Chung, Min-Chul
    • Korean Chemical Engineering Research
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    • v.49 no.6
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    • pp.720-725
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    • 2011
  • Gold catalysts supported on metal-oxides were prepared by co-precipitation using the various metal nitrates and chloroauric acid as precursors, and effect of water addition on the catalytic activity in CO oxidation was investigated. Among the various supported gold catalysts, Au/$Co_{3}O_{4}$ and Au/ZnO catalysts showed the excellent activity for CO oxidation. Water in the reactant gas had a negative effect on the oxidation activity over Au/$Co_{3}O_{4}$ catalysts and a positive effect on that over Au/ZnO, which means the activity depends strongly on the nature of support. It was also confirmed that no significant change in the particle size of gold was observed after reaction both in dry and wet conditions. This fact suggested that the deactivated catalyst due to a carbonate species could be regenerated by water addition in the reactant gas.

Fabrication of hyaluronic acid membrane using electrospinning method and its application as a catalyst support for gold nanoparticles (전기방사를 이용한 히알루론산 멤브레인의 제조 및 금 나노입자 촉매 담체로의 응용)

  • Lee, Namhun;Park, Hyun-Min;Lee, Sang-Myung;Lee, Dae-Won
    • Journal of Industrial Technology
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    • v.38 no.1
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    • pp.15-19
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    • 2018
  • In this study, hyaluronic acid (HA) was electro-spun to fabricate nanofibrous membranes for support materials. Because HA is very hygroscopic, it is difficult to obtain enough viscosity to apply electrospinning method. Therefore, we mixed HA with polyethylene oxide (PEO) to obtain proper viscosity and added adipic acid (ADH) to promote cross-linking of PEO/HA during electrospinning. The morphology of PEO/HA membrane was optimized according to PEO/HA concentration ratio and spinning rate. Finally, we fabricated gold-nanoparticle-embedded PEO/HA membranes and their catalyst activities were evaluated in tetramethylbenzidine (TMB) oxidation.

ZnO Nanowires Fabricated by Pulsed Laser Deposition using Gold Catalyst (PLD-Furnace로 증착시킨 금촉매를 이용한 ZnO 나노와이어 합성)

  • Son, Hyo-Jeong;Jeon, Kyung-Ah;Lee, Sang-Yeol
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.5-6
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    • 2005
  • ZnO nanowlres (NWs) were fabricated using Au as catalyst for a method combining laser ablation cluster formation and vapor-liquid-solid (VLS) growth. The target used in synthesis was pure ZnO ceramics. Two different substrates were used; (0001)-oriented sapphires and Au-coated sapphires. The Au thin film was deposited by thermal evaporation and the thickness was about 50 ${\AA}$. ZnO NWs were only formed in case of that used catalyst metal. Field effect scanning electron microscopic (FESEM) investigation showed that the average diameter of ZnO NWs was about 70 nm and the typical lengths varied from $3{\sim}4{\mu}m$.

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