란타니드계촉매를 이용한 카바메이트의 합성

沈相喆,白振旭 경북대학교 산업기술연구소 1988 産業技術硏究誌 Vol.16 No.-

The reaction of 2-methyl-3-butyn-2-ol with secondary amine in the presence of a catalytic amount of lanthanide chloride in acetonitrile at 160℃ for 8 hr gave the corresponding 1, 1-dimethyl-2-oxopropyl N, N-dialkylcarbamate in reasonable yield with a small amount of N, N-dialkylacetamide under 20 atm of carbon dioxide. The yield of 1, 1-dimethyl-2-oxopropyl N, N-dialkyl carbamates depends of the catalyst. In the case of 1, 1-dimethyl-2-oxopropyl N, N-hexa-methylene carbamate, CeCl_3 gave 38% yield, but NdCl_3, CdCl_3, and PrCl_3 gave 20%, 22% and 27% yield, respectively.

입체 자수 기법을 적용한 마찰 에너지 수확 증대형 직물 구조의 탐색

양진희 ( Jin-hee Yang ),조현승 ( Hyun-seung Cho ),김민욱 ( Min-ook Kim ),김종백 ( Jong-baeg Kim ),김신혜 ( Shin-hye Kim ),이주현 ( Joo-hyeon Lee ) 한국감성과학회 2018 감성과학 Vol.21 No.3

본 연구의 목적은 첫째 마찰 시 직물의 면적을 증가시켜 에너지 수확의 효율을 높일 수 있는 입체 자수 기법 및 전도성 직물 재료를 탐색하고, 둘째 높은 효율을 보이는 입체 자수 기법을 토대로 브러싱 가공을 실시하여 가공 후의 발생 전압을 분석하며, 셋째 이를 근거로 마찰 에너지 수확 증대형 직물의 구조를 탐색하는 것이다. 이를 위해 다음의 두 가지 실험을 실시하였다. “실험 Ⅰ”에서는 인체로부터 마찰 에너지를 수확하는 효율에 영향을 미치는 직물 내 주요 변인으로, 1) 입체 자수 기법(사틴 기법, 파일 기법), 2) 전도성 직물 재료(구리 기반 MPF, 니켈 기반 MPF)를 선정하고, 이 두 변인들의 조합에 따른 4개의 시료를 제작하여 마찰 시 발생 전압의 차이를 비교 분석하였다. “실험Ⅱ”에서는 높은 효율을 보이는 입체 자수 방식의 시료를 대상으로 브러싱 가공을 실시하여 가공 후의 발생 전압을 분석하였다. 그 결과, 두 전도성 직물 재료 모두에 있어서 파일 자수 직물 구조가 사틴 자수 직물 구조에 비해 높은 마찰 에너지 수확 효율을 보였고, 이러한 결과는 마찰 면적에 따른 전하 밀도와 발생 전압이 비례하는 마찰 에너지 수확의 원리와 일치하였다. 이를 통해 마찰 면적이 큰 파일 자수 직물 구조가 마찰 면적이 상대적으로 작은 사틴자수 직물 구조에 비해 에너지 수확 효율을 증대시키는데 유리한 방식임을 알 수 있었다. 또한 브러싱 가공 후의 에너지 수확 효율도 마찰 면적 증대로 인해 가공 전에 비해 높게 나타나, 브러싱 가공 방식이 마찰 에너지 수확 증대에 있어서 유리한 가공 방식임을 알 수 있었다. The purpose of this study is to investigate three-dimensional embroidery techniques for creating conductive fabric materials. Such techniques can increase the efficiency of energy harvesting by increasing the fabric's area during rubbing and brushing. We also investigate the fabric structure of the triboelectric energy harvesting type. Two experiments were conducted for this purpose. In Experiment Ⅰ, the three-dimensional embroidery technique(satin technique, file technique) and the conductive fabric material(copper-based MPF, nickel-based MPF) were selected as the main variables affecting the efficiency of triboelectric energy harvesting from the human body. Four samples were fabricated according to a combination of two variables. In Experiment Ⅱ, the harvesters fabricated by the three-dimensional embroidery method showing the highest efficiency were subjected to brushing processes and the voltages generated after processing were analyzed. As a result, in both conductive fabric materials, the pile embroidery fabric structure showed a higher efficiency than the satin structure. These results show the triboelectric energy harvesting principle, which is proportional to the charge density and the generated voltage. It can be seen that the structure of pile embroidery fabric with a large friction area is advantageous for increasing efficiency compared to satin embroidery-fabric structure with a relatively small friction area. Moreover, the energy harvesting efficiency after brushing was higher than that before processing due to the increased friction area, and it was found that the brushing method is advantageous for increasing the triboelectric-energy harvest.

Visible Light Driven ZnFe2Ta2O9 Catalyzed Decomposition of H2S for Solar Hydrogen Production

Esakkiappan Subramanian,Jin-Ook Baeg*,Bharat B. Kale,Sang Mi Lee,문상진,Ki-jeong Kong 대한화학회 2007 Bulletin of the Korean Chemical Society Vol.28 No.11

Tantalum-containing metal oxides, well known for their efficiency in water splitting and H2 production, have never been used in visible light driven photodecomposition of H2S and H2 production. The present work is an attempt in this direction and investigates their efficiency. A mixed metal oxide, ZnFe2Ta2O9, with the inclusion of Fe2O3 to impart color, was prepared by the conventional ceramic route in single- and double-calcinations (represented as ZnFe2Ta2O9-SC and ZnFe2Ta2O9-DC respectively). The XRD characterization shows that both have identical patterns and reveals tetragonal structure to a major extent and a minor contribution of orthorhombic crystalline system. The UV-visible diffuse reflection spectra demonstrate the intense, coherent and wide absorption of visible light by both the catalysts, with absorption edge at 650 nm, giving rise to a band gap of 1.9 eV. Between the two catalysts, however, ZnFe2Ta2O9-DC has greater absorption in almost the entire wavelength region, which accounts for its strong brown coloration than ZnFe2Ta2O9-SC when viewed by the naked eye. In photocatalysis, both catalysts decompose H2S under visible light irradiation (l ³ 420 nm) and produce solar H2 at a much higher rate than previously reported catalysts. Nevertheless, ZnFe2Ta2O9-DC distinguishes itself from ZnFe2Ta2O9-SC by exhibiting a higher efficiency because of its greater light absorption. Altogether, the tantalum-containing mixed metal oxide proves its efficient catalytic role in H2S decomposition and H2 production process also.

A solar light-driven, eco-friendly protocol for highly enantioselective synthesis of chiral alcohols <i>via</i> photocatalytic/biocatalytic cascades

Choudhury, Sumit,Baeg, Jin-Ook,Park, No-Joong,Yadav, Rajesh K. The Royal Society of Chemistry 2014 Green Chemistry Vol.16 No.9

<P>The judicious utilization of solar light for the asymmetric synthesis of optically active compounds by imitating natural photosynthesis introduces a new concept that harnesses this renewable energy <I>in vitro</I> for ultimate transformation into chiral chemical bonds. Herein, we present a comprehensive description of such a biomimetic endeavor towards the design and construction of an asymmetric artificial photosynthesis system that comprises an efficient method of nicotinamide cofactor (NADPH) regeneration under visible light employing a graphene-based light harvesting photocatalyst and its subsequent utilization in an enzyme-catalyzed asymmetric reduction of prochiral ketones to expediently furnish the corresponding chiral secondary alcohols. A detailed optimization study revealed a major dependency of the reaction outcome on the amount of cofactor, photocatalyst and enzyme used, as well as the mode of their addition. A series of structurally diverse ketones bearing an array of (hetero)aryl/alkyl substituents proved to be highly suitable to our photocatalytic–biocatalytic cascade approach, providing (<I>R</I>/<I>S</I>)-1-(hetero)aryl/alkylethanols in excellent enantioselectivities (ee ∼ 95–>99.9%) under mild and environmentally benign conditions. To the best of our knowledge, the synthesis of these enantiopure alcohols employing a visible-light-driven nicotinamide cofactor regeneration strategy has been reported for the first time. Such enantioenriched alcohols act as versatile chiral building blocks for the synthesis of compounds having industrial and pharmaceutical relevance. In addition, this solar-to-chiral chemicals prototype appears advantageous from ecological and economical perspectives. We describe mechanistic pathways to demonstrate how the present catalytic synthesis protocol functions through perfect orchestration between visible-light-driven photocatalysis and biocatalysis to be successively applied in inducing asymmetry in an achiral molecule for the ultimate goal of solar energy utilization in the synthesis of valuable chiral fine chemicals. This work highlights the potential advantages of a bioinspired system to the pertinence of solar energy in asymmetric transformations leading to enantioenriched alcohol precursors, and thus opens up a new field of research that might emerge as an important breakthrough with promising implications towards generating a sustainable and non-fossil/non-nuclear energy future.</P> <P>Graphic Abstract</P><P>A bio-inspired synthetic cascade approach combining photocatalysis with biocatalysis allows for the solar-light-driven asymmetric reduction of ketones to produce chiral alcohols with excellent enantioselectivities. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4gc00885e'> </P>

Visible Light Driven ZnFe₂Ta₂O₉ Catalyzed Decomposition of H₂S for Solar Hydrogen Production

Subramanian, Esakkiappan,Baeg, Jin-Ook,Kale, Bharat B.,Lee, Sang-Mi,Moon, Sang-Jin,Kong, Ki-Jeong Korean Chemical Society 2007 Bulletin of the Korean Chemical Society Vol.28 No.11

Tantalum-containing metal oxides, well known for their efficiency in water splitting and H2 production, have never been used in visible light driven photodecomposition of H2S and H2 production. The present work is an attempt in this direction and investigates their efficiency. A mixed metal oxide, ZnFe2Ta2O9, with the inclusion of Fe2O3 to impart color, was prepared by the conventional ceramic route in single- and double-calcinations (represented as ZnFe2Ta2O9-SC and ZnFe2Ta2O9-DC respectively). The XRD characterization shows that both have identical patterns and reveals tetragonal structure to a major extent and a minor contribution of orthorhombic crystalline system. The UV-visible diffuse reflection spectra demonstrate the intense, coherent and wide absorption of visible light by both the catalysts, with absorption edge at 650 nm, giving rise to a band gap of 1.9 eV. Between the two catalysts, however, ZnFe2Ta2O9-DC has greater absorption in almost the entire wavelength region, which accounts for its strong brown coloration than ZnFe2Ta2O9-SC when viewed by the naked eye. In photocatalysis, both catalysts decompose H2S under visible light irradiation (λ ≥ 420 nm) and produce solar H2 at a much higher rate than previously reported catalysts. Nevertheless, ZnFe2Ta2O9-DC distinguishes itself from ZnFe2Ta2O9-SC by exhibiting a higher efficiency because of its greater light absorption. Altogether, the tantalum-containing mixed metal oxide proves its efficient catalytic role in H2S decomposition and H2 production process also.

A Photocatalyst–Enzyme Coupled Artificial Photosynthesis System for Solar Energy in Production of Formic Acid from CO₂

Yadav, Rajesh K.,Baeg, Jin-Ook,Oh, Gyu Hwan,Park, No-Joong,Kong, Ki-jeong,Kim, Jinheung,Hwang, Dong Won,Biswas, Soumya K. American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.28

<P>The photocatalyst–enzyme coupled system for artificial photosynthesis process is one of the most promising methods of solar energy conversion for the synthesis of organic chemicals or fuel. Here we report the synthesis of a novel graphene-based visible light active photocatalyst which covalently bonded the chromophore, such as multianthraquinone substituted porphyrin with the chemically converted graphene as a photocatalyst of the artificial photosynthesis system for an efficient photosynthetic production of formic acid from CO<SUB>2</SUB>. The results not only show a benchmark example of the graphene-based material used as a photocatalyst in general artificial photosynthesis but also the benchmark example of the selective production system of solar chemicals/solar fuel directly from CO<SUB>2</SUB>.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-28/ja3009902/production/images/medium/ja-2012-009902_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja3009902'>ACS Electronic Supporting Info</A></P>

Confinement of nano CdS in designated glass: a novel functionality of quantum dot–glass nanosystems in solar hydrogen production

Kale, Bharat B.,Baeg, Jin-Ook,Apte, Sanjay K.,Sonawane, Ravindra S.,Naik, Sonali D.,Patil, Kashinath R. Royal Society of Chemistry 2007 Journal of materials chemistry Vol.17 No.40

<P>The present work is the investigation of our novel approach to designing quantum dot–glass nanosystems by confining nano CdS in designated glass and the first employment of such a quantum dot system in solar hydrogen production. The CdS quantum dots were grown in a special glass matrix, which involved a sequence of steps. The obtained glass was of uniformly bright yellow in color and the bulk glass was pulverized to a fine powder of micron size particles. The glass powder was characterized structurally and morphologically. X-Ray diffraction and electron diffraction patterns reveal a hexagonal crystallite system for the CdS quantum dots. Field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy and chemical leaching with HCl studies demonstrate that the 2.5 nm size CdS quantum dots distribute homogeneously in a monodispersed form in the glass domain and on the surface with a “partially embedded exposure” configuration. This disposition imparts an excellent photostability against photocorrosion and also a facile catalytic function. Therefore, even a very small amount of CdS quantum dots (0.005 g per gram of glass powder) is able to photodecompose H<SUB>2</SUB>S under visible light (<I>λ</I> ≥ 420 nm) both in alkaline and pure aqueous media and produce solar hydrogen with markedly high quantum yields of 17.5 and 11.4%, respectively at 470 nm. Salient features like reusability after simple washing, corrosionless-stability and remarkable catalytic activity of this quantum dot–glass nanosystem are brought forth by our novel catalyst design and are much acclaimed in large scale solar H<SUB>2</SUB> production.</P> <P>Graphic Abstract</P><P>CdS quantum dots (∼2.5 nm) in a “partially embedded exposure” configuration were grown in a special glass matrix. This nanosystem was employed for the first time for the photocatalytic production of H<SUB>2</SUB> under visible light. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=b708269j'> </P>

Morphologically different WO3 nanocrystals in photoelectrochemical water oxidation

Biswas, Soumya Kanti,Baeg, Jin-Ook,Moon, Sang-Jin,Kong, Ki-jeong,So, Won-Wook Springer-Verlag 2012 Journal of nanoparticle research Vol.14 No.1

Hydroisomerization of n-Heptane over Modified USY-Supported H₃PW_(12)O_(40) Catalysts : Effect of Hydrothermal Treatment for USY

Wang, Jun,Jiang, Dongmei,Baeg, Jin-Ook,Lee, Chul Wee 한국공업화학회 2004 Journal of Industrial and Engineering Chemistry Vol.10 No.3

We have prepared Pt-bearing modified USY-supported 12-tungstophosphoric acid catalysts from supports that were treated hydrothermally at various temperatures and time. The catalysts were characterized by XRU, 1R spectroscopy, and NH₃-TPD techniques, and measured for their hydroisomerization of n-heptane in an atmospheric fixed-bed microreactor. We found that the PW-bearing catalysts showed much higher catalytic activity than do the PW-free counterparts, and that the hydrothermal conditions for the USY support could influence the catalytic activity substantially. Hydrothermal treatment at 650℃ for 5 h was the optimum treatment condition; it leads to a high conversion of n-heptane (30.1%) with a very high selectivity for isomerization (98.2%). We discuss the catalytic activities in relation to the physical and chemical properties of the catalysts.

Uniform coating of TiO2 thin films on particles by rotating cylindrical PCVD reactor.

Kim, Dong-Joo,Baeg, Jin-Ook,Moon, Sang-Jin,Kim, Kyo-Seon American Scientific Publishers 2009 Journal of Nanoscience and Nanotechnology Vol.9 No.7

<P>We analyzed TiO2 thin film growth on glass particles in a rotating cylindrical plasma chemical vapor deposition (PCVD) reactor and numerically investigated the effects of several process variables on the film growth. An increase in titanium tetra-isopropoxide (TTIP) or O2 partial pressure can enhance the film growth rate on the particles because the concentration of TiO(x), which is the main precursor for thin film growth, becomes higher in the reactor. As the particle diameter decreases, the TiO(x) concentration increases and the thin film on the particles grows more quickly. The neutral-radical reaction between TTIP and O radicals for TiO(x) generation in TTIP + O2 plasmas can be important to enhance the thin film growth rate on the particles. The growth rate of TiO2 film predicted in this study was 1 approximately 20 nm/min, which is in good agreement with the published experimental results. This study suggests that a uniform TiO2 thin film on particles can be obtained by using a rotating cylindrical PCVD reactor.</P>