• Title/Summary/Keyword: microwave-assisted polyol

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Synthesis and Study of Pt/MWCNTs Catalysts by Using Microwave Assisted Polyol Method for PEM Fuel Cells (마이크로파-폴리올법을 이용한 고분자 전해질 연료전지용 Pt/MWCNTs 촉매의 제조 및 이의 특성분석)

  • Lee, Tae Kyu;Hur, Seung Hyun
    • Journal of the Korean Electrochemical Society
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    • v.15 no.4
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    • pp.264-269
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    • 2012
  • In this study, highly loaded(50 wt%) and very stable Pt/MWCNT catalysts for Polymer Electrolyte Membrane Fuel Cells(PEMFCs) are synthesized in short time scale by microwave assisted polyol method with different microwave irradiation time. The XRD and TEM results show that the Pt size becomes bigger as the microwave irradiation time increases. The mean Pt sizes of fabricated catalysts are 4.1, 4.9 and 8.5 nm when the microwave are irradiated for 10, 20 and 30 min, respectively. When compared with Pt catalyst made by conventional polyol method, it shows better long term durability due to the better Pt dispersion on the MWCNT surface.

Characteristics of Pt, Pt-Ru and Pt-CeO2 Catalysts Supported on Carbon Nanotubes for Methanol Fuel Cell (탄소 나노튜브에 담지된 Pt, Pt-Ru 및 Pt-CeO2 메탄올 연료전지 촉매의 특성)

  • Hwang, Gui-Sung;Lee, Rhim-Youl
    • Korean Journal of Materials Research
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    • v.21 no.3
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    • pp.138-143
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    • 2011
  • Nanosized Pt, Pt-Ru and Pt-$CeO_2$ electrocatalysts supported on acid-treated carbon nanotube (CNT) were synthesized by microwave-assisted heating of polyol process using $H_2Cl_6Pt{\cdot}6H_2O$, $RuCl_3$, $CeCl_3$ precursors, respectively, and were characterized by XRD and TEM. And then the electrochemical activity of methanol oxidation for catalyst/CNT nanocomposite electrodes was investigated. The microwave assisted polyol process produced the nano-sized crystalline catalysts particles on CNT. The size of Pt supported on CNT was 7~12 nm but it decreased to 3~5 nm in which 10wt% sodium acetate was added as a stabilizer during the polyol process. This fine Pt catalyst particles resulted in a higher current density for Pt/CNT electrode. It was also found that 10 nm size of PtRu alloys were formed by polyol process and the onset potential decreased with Ru addition. Cyclic voltammetry analysis revealed that the $Pt_{75}Ru_{25}/CNT$ electrode had the highest electrochemical activity owing to a higher ratio of the forward to reverse anodic peak current. And the chronoamperemetry test showed that $Pt_{75}Ru_{25}$ catalyst had a good catalyst stability. The activity of Pt was also found to be improved with the addition of $CeO_2$.

Synthesis of Metal Doped ZnO Nanoclusters by Microwave Assisted Polyol Process (마이크로웨이브 폴리올 공정에서 금속 도핑 산화아연 나노클러스터의 합성)

  • Kwon, Oh-San;Kang, Kuk-Hyoun;Lee, Dong-Kyu
    • Journal of the Korean Applied Science and Technology
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    • v.31 no.3
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    • pp.525-533
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    • 2014
  • ZnO has attracted much attention such as photocatalysts, sensors, piezoelectricity and etc. At present, an economical and rapid synthesis route based on the efficient microwave polyol process is used to synthesized metal-doped ZnO nanoclusters. Diethylene glycol has a property of high polarizability, and is an excellent microwave absorbing agent, thus leading to a high heating rate and a significantly shorter reaction time. In this study, metal-doped ZnO nanoclusters are obtained with different seed volumes, when zinc acetate dihydrate is used as a precursor, and metal acetate hydrate is used as a doped-metal and diethylene glycol is used as a solvent. The obtained metal-doped ZnO nanoclusters were characterized by FE-SEM, XRD, Raman and PSA.

Synthesis and Property of Carbon Nanotube-Supported Pd and Pt Nanoparticles (탄소나노 튜브위에 성장된 Pd 및 Pt 나노 입자의 제조 및 특성)

  • Kim, Hyung-Kun;Lee, Rhim-Youl
    • Korean Journal of Materials Research
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    • v.19 no.4
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    • pp.192-197
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    • 2009
  • Carbon nanotubes (CNT) were used as a catalyst support where catalytically active Pd and Pt metal particles decorated the outside of the external CNT walls. In this study, Pd and Pt nanoparticles supported on $HNO_3$-treated CNT were prepared by microwave-assisted heating of the polyol process using $PdCl_2$ and $H_2PtCl_6{\codt}6H_2O$ precursors, respectively, and were then characterized by SEM, TEM, and Raman. Raman spectroscopy showed that the acid treated CNT had a higher intensity ratio of $I_D/I_G$ compared to that of non-treated CNT, indicating the formation of defects or functional groups on CNT after chemical oxidation. Microwave irradiation for total two minutes resulted in the formation of Pd and Pt nanoparticles on the acid treated CNT. The sizes of Pd and Pt nanoparticles were found to be less than 10 nm and 3 nm, respectively. Furthermore, the $SnO_2$ films doped with CNT decorated by Pd and Pt nanoparticles were prepared, and then the $NO_2$ gas response of these sensor films was evaluated under $1{\sim}5\;ppm$ $NO_2$ concentration at $200^{\circ}C$. It was found that the sensing property of the $SnO_2$ film sensor on $NO_2$ gas was greatly improved by the addition of CNT-supported Pd and Pt nanoparticles.