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Synthesis of Durable Small-sized Bilayer Au@Pt Nanoparticles for High Performance PEMFC Catalysts
Dorjgotov, Altansukh,Jeon, Yukwon,Hwang, Jeemin,Ulziidelger, Byambasuren,Kim, Hyeong Su,Han, Byungchan,Shul, Yong-Gun Elsevier 2017 ELECTROCHIMICA ACTA Vol.228 No.-
<P><B>Abstract</B></P> <P>Design of small-sized Au@Pt core-shell nanocatalysts with high activity and stability is crucial area for a wide range of electronic and chemical devices. Here, we report a novel reduction method using UV treatment at room temperature by a weak reducing agent of H<SUB>2</SUB>O<SUB>2</SUB> enabling to produce carbon-supported small Au nanoparticles as the core of Pt shells. Different thicknesses of Pt layers are deposited on the Au to configure small-sized core@shell nanocatalysts. We acquire superior catalytic activity of Au@Pt catalysts toward cyclic voltammetry analysis and oxygen reduction reaction (ORR) via atomic level control of the particle size and the electronic structure. Underlying mechanism of the ORR activity is described from the aspect of compressive strain caused by shorter Au-Au distance than the bulk counterpart. The thickness of the Pt shell is shown to play an important role in stabilizing the nanocatalyst. Using density functional theory (DFT) calculations we validate the experimental outcomes. Top-quality power density above 2Wcm<SUP>−2</SUP> at low Pt loading (0.1mgcm<SUP>−2</SUP>) is achieved by a bilayer small-size Au@Pt core-shell catalyst with an excellent durability over 10,000 cycles by ADT, which is, indeed, beyond the recent DOE targets for a proton exchange membrane fuel cell system.</P>
Ulziidelger Byambasuren,Yukwon Jeon,Dorjgotov Altansukh,Yunseong Ji,Yong-Gun Shul 한국탄소학회 2016 Carbon Letters Vol.17 No.-
Nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a dual transition metal system were synthesized as non-Pt catalysts for the ORR. The highly nitrogen doped OMCs were prepared by the precursor of ionic liquid (3-methyl-1-butylpyridine dicyanamide) for N/C species and a mesoporous silica template for the physical structure. Mostly, N-doped carbons are promoted by a single transition metal to improve catalytic activity for ORR in PEMFCs. In this study, our N-doped mesoporous carbons were promoted by the dual transition metals of iron and cobalt (Fe, Co), which were incorporated into the N-doped carbons lattice by subsequently heat treatments. All the prepared carbons were characterized by via transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). To evaluate the activities of synthesized doped carbons, linear sweep was recorded in an acidic solution to compare the ORR catalytic activities values for the use in the PEMFC system. The dual transition metal promotion improved the ORR activity compared with the single transition metal promotion, due to the increase in the quaternary nitrogen species from the structural change by the dual metals. The effect of different ratio of the dual metals into the N doped carbon were examined to evaluate the activities of the oxygen reduction reaction.
Jeon, Y.,Park, J.I.,Ok, J.,Dorjgotov, A.,Kim, H.J.,Kim, H.,Lee, C.,Park, S.,Shul, Y.G. Pergamon Press ; Elsevier Science Ltd 2016 International journal of hydrogen energy Vol.41 No.16
<P>As a new carbon support for high temperature proton exchange membrane fuel cell (HT-PEMFC), the nitrogen doped CNF/ACF (N/CNF/ACF) was synthesized by coating and annealing the polypyrrole to the surface of carbon nanofiber (CNF) grown on activated carbon fiber (ACF). The durability and electrochemical performance of Pt/N/CNF/ACF and commercial Pt/C was examined and compared with various analytical tools as well as accelerated life-time test (ALT) at high temperature of 120 degrees C. The catalytic durability on Pt/N/CNF/ACF was improved due to the enhanced pi-bonding and the basic electron donor property of nitrogen contents. Such stability of Pt/N/CNF/ACF was originated from the strong interaction between Pt particles and carbon matrix with nitrogen contents. The evidences on the nitrogen effect of Pt/N/CNF/ACF were elucidated with the gentle loss of electrochemical active surface area (ECSA) and the shift of XPS peak (Pt 4f) to the direction of higher binding energy, comparing with those of commercial PVC, before and after ALT. The physical and chemical properties on the Pt/N/CNF/ACF was characterized with HR-TEM, FE-SEM, FT-IR, XRD and XPS, in detail. And, their electrochemical properties for HT-PEMFC were examined with single cell and half cell test, before and after ALT. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.</P>
The development of complex electrode for fuel cell using CNT
옥진희(Ok, Jinhee),이준기(Rhee, Junki),Altalsukh, Dorjgotov,Rhee, Junki,박상선(Park, Sangsun),설용건(Shul, Yonggun) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Carbon nanotube(CNT) has been spotlighted as a promising candidate for catalyst support material for PEMFC (proton exchange membrane fuel cell). The considerable properties of CNT include high surface area, outstanding thermal, electrical conductivity and mechanical stability. In this study, to fully utilize the properties of CNTs, we prepared directly oriented CNT on carbon paper as a catalyst support in the cathode electrode. The CNT layer was prepared by a chemical vapor deposition(CVD) process. And the Pt particles were deposited on the CNT oriented carbon paper by impregnation and eletro-deposition method. The potential advantages of directly oriented CNT on carbon paper can include improved thermal and charge transfer through direct contact between the electrolyte and the electrode and enhanced exposure of Pt catalyst sites during the reaction.