• Carbon letters
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• v.10 no.3
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• pp.213-216
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• 2009

The electrochemical deposition of Pt nanoparticles on carbon nanotubes (CNTs) supports and their catalytic activities for methanol electro-oxidation were investigated. Pt catalysts of 4~12 nm average crystalline size were grown on supports by potential cycling methods. Electro-plating of 12 min time by potential cycling method was sufficient to obtain small crystalline size 4.5 nm particles, showing a good electrochemical activity. The catalysts' loading contents were enhanced by increasing the deposition time. The crystalline sizes and morphology of the Pt/support catalysts were evaluated using X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The electrochemical behaviors of the Pt/support catalysts were investigated according to their characteristic current-potential curves in a methanol solution. In the result, the electrochemical activity increased with increased plating time, reaching the maximum at 12 min, and then decreased. The enhanced electroactivity for catalysts was correlated to the crystalline size and dispersion state of the catalysts.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.191-194
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• 2009

PtRu based and PtSn based ternary catalysts were prepared by a conventional impregnation method using NaBH4 as reducing agent. The alloy formation, crystalline size and chemical composition of the in-house catalysts were determined by XRD, TEM and EDX, respectively. The chemical compositions of in-house catalysts were quite similar to the nominal value and good alloy formations were also observed. Further, crystalline sizes of ternary catalysts were comparatively smaller than binary catalysts and were approximately 3.5 ~ 5.5 nm. The electrochemical measurements were carried out in the solution 1 M $H_2SO_4$ with 1 M $C_2H_5OH$ at room temperature. LSV results obtained that ternary catalysts were higher current densities and specific activities. Especially, in case of tungsten addition system, Pt5Sn4W/C have the highest specific activities values and was approximately 21.2 and 3.1 times higher than that of PtRu/C and PtSn/C electrocatalyst.

• Korean Journal of Materials Research
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• v.21 no.8
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• pp.419-424
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• 2011

Pt nanoparticle catalysts incorporated on $RuO_2$ nanowire support were successfully synthesized and their electrochemical properties, such as methanol electro-oxidation and electrochemically active surface (EAS) area, were demonstrated for direct methanol fuel cells (DMFCs). After fabricating $RuO_2$ nanowire support via an electrospinning method, two different types of incorporated Pt nanoparticle electrocatalysts were prepared using a precipitation method via the reaction with $NaBH_4$ as a reducing agent. One electrocatalyst was 20 wt% Pt/$RuO_2$, and the other was 40 wt% Pt/$RuO_2$. The structural and electrochemical properties of the Pt nanoparticle electrocatalysts incorporated on electrospun $RuO_2$ nanowire support were investigated using a bright field transmission electron microscopy (bright field TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry. The bright field TEM, XRD, and XPS results indicate that Pt nanoparticle electrocatalysts with sizes of approximately 2-4 nm were well incorporated on the electrospun $RuO_2$ nanowire support with a diameter of approximately 50 nm. The cyclic voltammetry results showed that the Pt nanoparticle catalysts incorporated on the electrospun $RuO_2$ nanowire support give superior catalytic activity in the methanol electro-oxidation and a higher electrochemically active surface (EAS) area when compared with the electrospun Pt nanowire electrocatalysts without the $RuO_2$ nanowire support. Therefore, the Pt nanoparticle catalysts incorporated on the electrospun $RuO_2$ nanowire support could be a promising electrode for direct methanol fuel cells (DMFCs).

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3145-3150
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• 2010

Ruthenium catalysts modified by selenium have been introduced as alternative materials to Pt in Direct methanol fuel cells (DMFCs). RuSe nano-particles were synthesized on the Vulcan XC72R carbon supports via polyol method. The prepared catalysts were electrochemically and physically characterized by cyclic voltammetry (CV,) linear sweep voltammetry, methanol tolerance test, X-ray diffraction (XRD), Transmission electron microscopy (TEM), Energydispersive Spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). Increasing the Se concentration up to 20 at % increased the electro-catalytic activity for the oxygen reduction. By increasing Se amount, Ru metallic form on the surface was increased. The $Ru_{80}Se_{20}$/C catalysts showed the highest oxygen reduction reaction (ORR) activity and outstanding methanol tolerant property in half cell tests as well as single cell test.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.652-655
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• 2009

The bimodal porous carbons were synthesized by using imprinting method with templates of SBA-15 particle and silica sphere and applied as supporting materials for the electro-catalyst of polymer electrolyte fuel cell (PEFC). The silica spheres with diameter size of 100 nm and SBA-15 particle having 200 nm -250 nm diameter and 700 nm -900 nm length were synthesized in this work. The bimodal porous carbons (S100) were prepared by using the silica spheres and SBA-15 as templates and mesophase pitch as a carbon source. The PtRu nanoparticle of ca. 1.9 nm were supported on the bimodal porous carbon support and the resulting PtRu/S100 catalysts was tested by the cyclic voltammetry. The use of bimodal porous carbon showed in comparable electro-catalytic activities with commercial catalyst. Though unclear effects of bimodal porosity of supports could be obtained in the scope of this study, morphological advantage in electrical conductivity can be considered on the electro-catalytic activity.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.387-391
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• 2019

A highly porous Ni@MIL-101catalyst for urea oxidation was synthesized by anchoring Ni into a Cr-based metal-organic framework, MIL-101, particles. The morphology, structure, and composition of as synthesized Ni@MIL-101 catalysts were characterized by X-Ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. The electro-catalytic activity of the Ni@MIL-101catalysts towards urea oxidation was investigated using cyclic voltammetry. It was found that the structure of Ni@MIL-101 retained that of the parent MIL-101, featuring a high BET surface area of $916m^2g^{-1}$, and thus excellent electro-catalytic activity for urea oxidation. A $urea/H_2O_2$ fuel cell with Ni@MIL-101 as anode material exhibited an excellent performance with maximum power density of $8.7mWcm^{-2}$ with an open circuit voltage of 0.7 V. Thus, this work shows that the highly porous three-dimensional Ni@MIL-101 catalysts can be used for urea oxidation and as an efficient anode material for urea fuel cells.

• Bulletin of the Korean Chemical Society
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• v.35 no.12
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• pp.3576-3582
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• 2014

Zeolite-templated carbons (ZTCs), which have high specific surface area, were prepared by a conventional templating method using microporous zeolite-Y for catalyst supports in direct methanol fuel cells. The ZTCs were synthesized at different temperatures to investigate the characteristics of the surface produced and their electrochemical properties. Thereafter, Pt-Ru was deposited at different carbonization temperatures by a chemical reduction method. The crystalline and structural features were investigated using X-ray diffraction and scanning electron microscopy. The textural properties of the ZTCs were investigated by analyzing $N_2$/77 K adsorption isotherms using the Brunauer-Emmett-Teller equation, while the micro- and meso-pore size distributions were analyzed using the Barrett-Joyner-Halenda and Harvarth-Kawazoe methods, respectively. The surface morphology was characterized using transmission electron microscopy and inductively coupled plasma-mass spectrometry. The electrochemical properties of the Pt-Ru/ZTCs catalysts were also analyzed by cyclic voltammetry measurements. From the results, the ZTCs carbonized at $900^{\circ}C$ show the highest specific surface areas. In addition, ZTC900-PR led to uniform dispersion of Pt-Ru on the ZTCs, which enhanced the electro-catalytic activity of the Pt-Ru catalysts. The particle size of ZTC900-PR catalyst is about 3.4 nm, also peak current density from the CV plot is $12.5mA/cm^2$. Therefore, electro-catalytic activity of the ZTC900-PR catalyst is higher than those of ZTC1000-PR catalyst.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.159-159
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• 2009

In this work, nitrogen and oxygen functionalities was introduced to the graphite nanofibers (GNFs) and their effect on electrocatalytic performance of the GNF supports for direct methanol fuel cells (DMFCs) was invesigated. The nitrogen and oxygen groups were introduced through the urea treatments and acid treatment, respectively. And, PtRu catalysts deposited on modified GNFs were prepared by a chemical reduction method. The catalysts were characterized by means of elemental analysis, nitrogen adsorption, and X-ray photoelectron spetroscopy (XPS). The structure and morphological characteristics of the catalysts were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). As a result, the Pt-Ru nanoparticles were impregnated on GNFs with good formation in 3-5 nm. And, the cyclic voltammograms for methanol oxidation revealed that the methanol oxidation peak varied depending on changes of surface functional groups. It was thus considered that the PtRu deposition was related to the reduction of PtRu and surface characteristics of the carbon supports. The changes of surface functional groups were related to PtRu reduction, significantly affect the methanol oxidation activity of anode electrocatalysts in DMFCs.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.369-372
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• 2009

In the present study, the effect of chemical treatment on graphite nanofibers (GNFs) supports with various concentrated nitric acids was investigated for methanol oxidation. To optimize the electrocatalytic activity, PtRu catalysts were deposited on GNF supports by impregnation method. The surface and structural properties of the GNF supports were characterized by X-ray photoelectron spectroscopy (XPS), element analyzer (EA), and X-ray diffraction (XRD). The morphology of the catalysts was observed by means of transmission electron microscopy (TEM). The electrocatalytic activity of PtRu/GNF catalysts was investigated by cyclic voltammetry measurement. As a result, the oxygen functional groups were introduced on the GNF supports and were gradually increased with increasing of concentrated nitric acid, causing the smaller particle size and higher loading level. And the electrocatalytic activity of the catalysts for methanol oxidation was gradually improved. Consequently, it was found that chemical treatments could influence on surface properties of the carbon supports, resulting in enhancing the electrocatalytic activity of the catalysts for DMFCs.

• Journal of Electrochemical Science and Technology
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• v.6 no.3
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• pp.95-105
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• 2015

In the present work, Carbon supported Pt₁₀₀, Pt₈₀Sn₂₀, Pt₈₀Ni₂₀ and Pt₈₀Sn₁₀Ni₁₀ electrocatalysts with different atomic ratios were prepared by ethylene glycol-reduction method to study the electro-oxidation of ethanol in membraneless fuel cell. The electrocatalysts were characterized in terms of structure, morphology and composition by using XRD, TEM and EDX techniques. Transmission electron microscopy measurements revealed a decrease in the mean particle size of the catalysts for the ternary compositions. The electrocatalytic activities of Pt₁₀₀/C, Pt₈₀Sn₂₀/C, Pt₈₀Ni₂₀/C and Pt₈₀Sn₁₀Ni₁₀/C catalysts for ethanol oxidation in an acid medium were investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The electrochemical results showed that addition of Ni to Pt/C and Pt-Sn/C catalysts significantly shifted the onset of ethanol and CO oxidations toward lower potentials. The single membraneless ethanol fuel cell performances of the Pt₈₀Sn₁₀Ni₁₀/C, Pt₈₀Sn₂₀/C and Pt₈₀Ni₂₀/C anode catalysts were evaluated at room temperature. Among the catalysts investigated, the power density obtained for Pt₈₀Sn₁₀Ni₁₀/C (37.77 mW/cm² ) catalyst was higher than that of Pt₈₀Sn₂₀/C (22.89 mW/cm² ) and Pt₈₀Ni₂₀/C (16.77 mW/ cm² ), using 1.0 M ethanol + 0.5 M H₂SO₄ as anode feed and 0.1 M sodium percarbonate + 0.5 M H₂SO₄ as cathode feed.