• Title, Summary, Keyword: mesoporous structure

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Synthesis of Mesoporous Transition Metal Carbon Using the Mesoporous Silica (메조포러스실리카를 이용한 메조포러스 전이금속체 합성)

  • Han, Seung-Dong;Jeong, Ui-Min;Lee, Joo-Bo;Peng, Mei Mei;Kim, Dae-Kyung;Jang, Hyun-Tae
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.4
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    • pp.1915-1922
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    • 2012
  • In this study, synthesis of mesoporous silica such as, SBA-15, MCM-41, MCM-48, KIT-6 according to various experimental conditions. The CMK(Carbon Mesoporous Korea) was synthsized by various mesoporous silica. Finally, the mesoporous transition metal structure synthesized using CMK structure. Nitrogen adsorption/ desorption, SEM, low angle X-ray diffraction were carried for analysis of each sample. The optimum synthesis condition of mesoporous transition metal structure derived from characteristic analysis. The SBA-15 is best precursor for synthesis of mesoporous transition metal structure. The surface area of copper mesorporous structure from CMK(SBA-15) is $225m^2/g$, pore diameter is 2.91nm by BET analysis.

Mesoporous Assembly of Layered Titanate with Well-Dispersed Pt Cocatalyst

  • Jung, Tae-Sung;Kim, Tae-Woo;Hwang, Seong-Ju
    • Bulletin of the Korean Chemical Society
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    • v.30 no.2
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    • pp.449-453
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    • 2009
  • A mesoporous assembly of layered titanate with well-dispersed Pt cocatalysts has been synthesized via a restacking of exfoliated titanate nanosheets and a simultaneous adsorption of Pt nanoparticles. According to powder X-ray diffraction analysis, the obtained mesoporous assembly shows amorphous structure corresponding to the disordered stacking of layered titanate crystallites. Field emission-scanning electron microscopy and $N_2$ adsorption-desorption isotherm measurement clearly demonstrate the formation of mesoporous structure with expanded surface area due to the house-of-cards type stacking of the titanate crystallites. From high resolution-transmission electron microscopy and elemental mapping analyses, it is found that Pt nanoparticles with the size of ~2.5 nm are homogeneously dispersed in the mesoporous assembly of layered titanate. In comparison with the protonated titanate, the present mesoporous assembly of layered titanate exhibits better photocatalytic activity for the photodegradation of organic molecules. This finding underscores that the restacking of exfoliated nanosheets is quite useful not only in creating mesoporous structure but also in improving the photocatalytic activity of titanium oxide.

The Phosphorus Removal from Water by Zirconium Mesoporous Structure (지르코늄 메조기공 구조체를 이용한 수중의 인 제거)

  • Lee, Byoung-cheun;Lee, Kwan-yong;Lee, Sang-hyup;Choi, Yong-su;Park, Ki-young
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.4
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    • pp.455-461
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    • 2005
  • This study was designed to investigate the fundamental aspects of a possible recovery of phosphorus strategy from wastewater by using the zirconium mesoporous structured materials as a new type of ion exchangers. Zirconium mesoporous structure material was synthesized by hydro-thermal synthesis. The synthesized zirconium mesoporous structure was examined by X-ray diffraction (XRD) and Transmission electron micrograph (TEM). From the results of XRD and TEM, it was found out that hexagonal mesoporous structure, pore size was about $47{\AA}$, was synthesized. Experimental results showed that the complex of zirconium sulfate tetrahydrate and surfactant micelles had very high ability for capture of phosphorus. The amount of phosphate ions exchanged into the solid was as great as 3.4mmol/g-ZS. And the ion exchange reaction was occurred between $PO_4{^{3-}}$ and $SO_4{^{2-}}$ and also between $PO_4{^{3-}}$ and $OH^-$. Therefore, it is possible to get the higher removal efficiency than other ion exchange media and adsorbent.

Synthesis of Ordered Mesoporous Manganese Oxides by Double Replication for Use as an Electrode Material

  • Guo, Xiao-Feng;Kim, Geon-Joong
    • Bulletin of the Korean Chemical Society
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    • v.32 no.1
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    • pp.186-190
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    • 2011
  • Periodically ordered mesoporous manganese oxides were synthesized in a single and double replication procedure. Mesoporous SBA-15 and -16 silica and their reverse replica carbons were successively used as hard templates. The silica and carbon pore systems were infiltrated with $Mn(NO_3)_2{\cdot}xH_2O$ or $Mn(AcAc)_2$, which was then converted to $Mn_2O_3$ at 873 K; the silica and carbon matrix were finally removed by NaOH solution or calcinations in air. The structure of the mesoporous $Mn_2O_3$, using a carbon template, corresponds to that of the original SBA-15 and SBA-16 silica. The products consist of hexagonally arranged cylindrical mesopores with crystalline pore walls or cubic mesoporous pores. The structure of replica has been confirmed by XRD, TEM analysis, and its electrochemical properties were tested with cyclic voltammetry. Formation of $Mn_2O_3$ inside the mesoporous carbon pore system showed much improved electrical properties.

Fabrication of Mesoporous Carbon Nanofibers for Electrical Double-Layer Capacitors (전기 이중층 커패시터용 메조 다공성 탄소 나노섬유의 제조)

  • Lee, Do-Young;An, Geon-Hyoung;Ahn, Hyo-Jin
    • Korean Journal of Materials Research
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    • v.27 no.11
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    • pp.617-623
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    • 2017
  • Mesoporous carbon nanofibers as electrode material for electrical double-layer capacitors(EDLCs) are fabricated using the electrospinning method and carbonization. Their morphologies, structures, chemical bonding states, porous structure, and electrochemical performance are investigated. The optimized mesoporous carbon nanofiber has a high sepecific surface area of $667m^2\;g^{-1}$, high average pore size of 6.3 nm, and high mesopore volume fraction of 80 %, as well as a unifom network structure consiting of a 1-D nanofiber stucture. The optimized mesoporous carbon nanofiber shows outstanding electrochemical performance with high specific capacitance of $87F\;g^{-1}$ at a current density of $0.1A\;g^{-1}$, high-rate performance ($72F\;g^{-1}$ at a current density of $20.0A\;g^{-1}$), and good cycling stability ($92F\;g^{-1}$ after 100 cycles). The improvement of the electrochemical performance via the combined effects of high specific surface area are due to the high mesopore volume fraction of the carbon nanofibers.

Heat treatment effect on synthesis of mesoporous silica (Mesoporous Silica의 제조에 열처리가 끼치는 영향)

  • Park, Kyu-Sung;Kim, Duk-Su;Kim, Il-Doo;Kim, Ho-Gi
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • pp.1113-1115
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    • 2002
  • Mesoporous silica, MCM-41, was synthesized by sol-gel method. The organic structure-directing agent must be removed to make the desired proes. To achieve this, alternative calcination method using microwave oven was adapted to this removal stage. Microwave calcination was shown to provide a novel, rapid and inexpensive method of praparing nanoporous material. It was studied how the porous structure, surface area and pore size distribution were changes under microwave calcination.

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A simple route for preparing Au/mesoporous silica yolk/shell particles for Au-catalyzed reactions

  • Song, Young-Geon;Chang, Hochan;Lee, Kangtaek
    • The Korean Journal of Chemical Engineering
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    • v.34 no.7
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    • pp.1930-1935
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    • 2017
  • We present a simple route to prepare mesoporous hollow silica particles containing an Au core, i.e., yolk/shell particles, by sol-gel and selective etching processes. Using tetraethoxysilane as a silica precursor, zinc acetate as a base catalyst, and cetyltrimethylammonium chloride as a soft template in the presence of Au nanoparticles, double-layered mesoporous shells were produced in one step. Elemental analysis showed that the inner shell consists of zinc silicate and the outer shell is pure silica. Au/mesoporous silica yolk/shell nanoparticles were obtained by selective etching of the zinc oxide phase with citrate buffer. The particle structure and composition were studied by transmission electron microscopy with energy disperse spectroscopy, UV-vis spectroscopy, X-ray diffraction, and nitrogen sorption experiments. Formation of double shells on the Au core in a single step was explained by a difference in the formation rates of the silica and zinc silicate phases. Au/mesoporous yolk/shell particles showed a high catalytic activity for reduction of 4-nitrophenol.

Preparation and Characterization of Mesoporous Ceramic Materials (메조기공 세라믹 소재의 형성과 특성 분석)

  • Ha, Tae-Jung;Park, Hyung-Ho
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.8
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    • pp.593-601
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    • 2012
  • Ordered mesoporous oxide films have been focused because of their low density, high interior specific surface area, and high thermal insulation. Specially, the ordered mesoporous oxide films prepared by self-assembly has many advantages due to easy process and high reproducibility. In this work, ordered mesoporous $SiO_2$, $Al_2O_3$, and $TiO_2$ films were synthesized by control of composition and processing parameter. Also, their structural, thermal, and mechanical properties were characterized variously. In conclusion, ordered mesoporous oxides will be one of core materials in new technology due to their excellent and unique properties.

Preparation and Characterization of Mesoporous Ni Film Made by Electroplating Method (전착법을 이용한 메조포러스 니켈 필름의 제조와 특성 분석)

  • Lee, Ji-Hoon;Baik, Young-Nam;Kim, Young-Seok;Shin, Seung-Han
    • Journal of the Korean institute of surface engineering
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    • v.40 no.1
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    • pp.16-22
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    • 2007
  • Recently, mesoporous metallic materials are becoming more and more important in various applications like catalysts, electrochemical detectors, batteries, and fuel cells because of their high surface area. Among the various methods for manufacturing mesoporous structure, surfactant templating method followed by electroplating has been tried in this study. A mesoporous metallic film was prepared by electrodeposition from electroplating solution mixed with surfactant template. Nonionic type lyotropic liquid crystalline surfactant, Brij56, and nickel acetate based solution were selected as a template material and electroplating solution, respectively. To determine the content of surfactant forming a hexagonal column structure, the phase diagram of electroplating solution and surfactant mixture has been exploited by polarized optical microscopy equipped with heating and cooling stage. Nickel films were electroplated on Cu foil by stepwise potential input method to alleviate the concentration polarization occurred during the electroplating process. TEM and XRD analyses were performed to characterize the size and shape of mesostructures in manufactured nickel films, and electrochemical characterization was also carried out using cyclic voltammetry.