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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.
Yong-Gun Shul,Ulziidelger Byambasuren,Yu Kwon Jeon,Dorjgotov Altansukh,Yunseong Ji 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.6
The particle size effect of N-doped mesoporous carbon was investigated for ORR activity in acid condition and for issue of a mass transfer and gas diffusion in PEMFCs. As for a non-Pt ORR catalyst, nitrogen (N)-doped ordered mesoporous carbons (OMCs) with a various particle sizes with the range of the average 20, 45 and 75 μm were synthesized by the precursor of polyaniline for the N/C species, and a mesoporous silica template was used for the physical structure for preparation of nitrogen doped OMCs. The N-doped mesoporous carbons are promoted by a transition metal (Fe) to improve catalytic activity for ORR in PEMFCs. All the prepared carbons were characterized by via scanning electron microscopy (SEM), and 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 surface area and pore volume were increased as the particles decreased, which was effective for the mass transfer of the reactant for higher activity at the limiting current regions.
Design of Au core-Palladium alloy shell nanoparticle for oxygen reduction reaction in fuel cells
이예연,설용건,김형수,전유권,박명근,( Ulziidelger Byambasuren ),황주순 한국공업화학회 2015 한국공업화학회 연구논문 초록집 Vol.2015 No.1
Platinum based nanomaterials are usually used as the electrocatalysts for both the cathode(oxygen reduction) and anode(hydrogen oxidation) reactions. However, the high cost of Pt in cathode catalyst and the slow kinetics of oxygen reduction reaction (ORR) on Pt-based catalysts hinder the commercialization of fuel cells. Instead of using platinum, recent studies have focused on the discovery of non platinum electrocatalysts which have excellent electrocatalytic activity and chemical stability. In this study, we synthesized gold core/palladium-Cobalt alloy shell catalysts. The developed catalysts showed excellent catalytic activity than Au core/Pd shell catalysts. The structural information and electrocatalytic activities of the Au core/Pd-Ir alloy shell nanoparticles were analyzed by XRD, XPS, HR-TEM, ORR test and cyclic voltammetry(CV).
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>