• 한국전기화학회:학술대회논문집
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• 2002.07a
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• pp.211-218
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• 2002

In this study, Pt/Pd (1.1), PtPd (2:1) and PtPd (3:1) binary catalysts and Pt/Ru/Pd (5:4:1) ternary catalyst were designed. The catalysts were synthesized by impregnation method using $NaBH_4$ as a reducing agent. A good catalyst for methanol oxidation requires low on-set potential, stable durability and low activation energy. In order to investigate the catalytic activity for the methanol oxidation, electrochemical measurements such as cyclic voltammetry and chronoamperometry were peformed in sulfuric acid with/without methanol solution. In order to calculate the activation energy of the reaction, electrochemical measurements were also tested at different temperatures. For investigation of the structural analysis such as particle size and alloying, X-ray diffraction and transmission electron microscopy analysis were used. In order to identify the role of the Pd and to determine the composition of the surface of the Pt/Pd nanoparticles, X-ray photoelectron spectroscopy (XPS) analysis was investigated. The XPS spectra of Pd showed that Pd appears only as a metallic state in the binary catalysts. The chemical states of Pt in PtPd catalysts are both metallic and oxidative. Polarization curves and power density data were obtained by testing the DMFC unit cell performance of PtPd and PtRuPd catalysts. These data showed that Pt/Pd (2:1) and Pt/Ru/Pd (5:4:1) have better performance than Pt and Pt/Ru, respectively.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.71.1-71.1
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• 2012

Proton Exchange Membrane Fuel Cells (PEMFCs) have been of great interest particularly in the automobile industries because of their high energy density and low pollutant emission. However, some of the issues such as, the necessarily high contents of Pt catalysts and their slow kinetics of cathode oxygen reduction reaction remain as obstacles in the commercialization of the PEMFC. In this presentation, after brief explanation on basic principles of PEMFC and its application to FC vehicles, recent researches to improve the activity and durability of Pt-based nano catalysts toward oxygen reduction will be introduced. It covers size and shape control of Pt nano particle, binary and ternary Pt-M alloys, novel core-shell nano structures of Pt, and a little bit about non-Pt catalysts. Strategies and methodologies for design and synthesis of novel catalysts will also be included.

• Korean Journal of Metals and Materials
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• v.47 no.7
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• pp.454-459
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• 2009

In order to commercialize Polymer Electrolyte Fuel Cell (PEFC), the cathode catalyst such as Platinum supported Carbon (Pt/C) need to have a high activity of Oxygen Reduction Reaction (ORR). In this study, the 20% Pt/C was synthesized using the chemical reduction method while the crystallinity of Platinum (Pt) particles were controlled under heat treatment conditions. The activity of synthesized Pt catalysts was evaluated using electrochemical measurement. Compared with the $i_{ORR}$ at 0.8 V of 20% Pt/C heat-treated at $500^{\circ}C$ and the 20% Pt/C that were not heated and commercial 20% Pt/C, the $i_{ORR}$ at 0.8 V of 20% Pt/C heattreated at $500^{\circ}C$ was 9.5 and 1.7 times higher than those of the 20% Pt/C and commercial 20% Pt/C that were not heated. It was considered that the crystallinity and particle size affect the ORR activity of the Pt/C catalysts.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.288-288
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• 2013

We report the catalytic activity of Au/$TiO_2$ and Pt/$TiO_2$ nanocatalysts under CO oxidation fabricated by arc plasma deposition (APD), which is a facile dry process with no organic materials involved. Using APD, the catalyst nanoparticles were well dispersed on $TiO_2$ powder with an average particle size (2~4 nm) well below that of nanoparticles prepared by the sol-gel method (10 nm). We found that the average particle size of the dispersed gold nanoparticles can be controlled by changing the plasma discharge voltage of APD. Accordingly, the amount of loaded gold on the $TiO_2$ powder increased with increasing discharge voltage, but the specific surface area of the Au/$TiO_2$ samples decreased. As for catalytic reactivity, Au/$TiO_2$ showed a higher catalytic activity than Pt/$TiO_2$ in CO oxidation. The catalytic activity of the Au/$TiO_2$ samples showed size dependence where higher catalytic activity occurred on smaller gold nanoparticles. The study suggests that APD is a simple way to fabricate catalytically active nanocatalysts.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.846-850
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• 2001

In the present study, nano-size powders of ternary ferrites, $Ni_{0.5}Zn_{0.5}Fe_2O_4$, as the potential catalysts of $CO_2$decomposition, were prepared by the wet processing of hydrothermal synthesis and coprecipitation method, and the catalyzing effects of impregnation of the noble metals, Pt and Pd, onto $Ni_{0.5}Zn_{0.5}Fe_2O_4$for the $CO_2$decomposition were investigated. XRD results of the synthesized ferrites showed a typical spinel structure of ferrite and the particle size was very small as about 6~10 nm. BET surface area of the ternary ferrites was not affected by the impregnation of Pt and Pd. The reactivity of the $CO_2$decomposition to carbon was improved by the impregnation of the noble metals of Pd and Pt. The effect of Pd-impregnation on the $CO_2$decomposition rate was higher than Pt-impregnation.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.459-467
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• 2022

Redispersion of Pt-Sn particles in Pt, PtSn catalyst which have been sintered by high temperature hydrogen reduction was investigated using oxygen treatment with various temperatures. The aim of this study was to understand the relationship between the catalytic activity for propane dehydrogenation reaction and the change in the physicochemical properties of the catalyst. X-ray diffraction analysis (XRD), CO pulse chemisorption, and H₂ temperature programmed reduction (H₂-TPR) were performed to investigate the state of active metal and interactions between particles of redispersed catalyst. It was confirmed that the dispersion and particle size of platinum, the crystal phase of the catalyst, and the reduction behavior were changed according to the oxygen treatment. As for the catalytic activity in propane dehydrogeantion, sintered PtSn catalyst treated with oxygen at 500 ℃ showed best activity and recovery of initial activity. It was confirm that catalyst after oxygen treatment at 500 ℃ showed high dispersion of Pt and decreased particle size as the results of CO pulse chemisorption and XRD of catalyst, and thus the redispersion of PtSn particles in sintered catalyst was occurred. Catalytic activity was recovered due to redispersion using oxygen treatment, and the activity recovery of the PtSn catalyst was higher than that of Pt catalyst.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.6
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• pp.549-555
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• 2019

Electrocatalysis of oxygen reduction reaction (ORR) using Pt nanoparticles or bimetal on carabon was studied. Currently, the best catalyst is platinum, which is a limited resource and expensive to commercialize. In this paper, we investigated the cheaper and more active electrocatalysts by making Pt nanoparticles and adding 3D transition metal such as copper. Electrocatalysts were obtained by chemical reduction based on ethylene glycol solutions. Elemental analysis and particle size were confirmed by XRD and TEM. The electrochemical surface area (ECSA) and activity of the catalyst were determined by electrochemical techniques such as cyclic voltammetry and linear sweep voltammetry method. The commercialized Pt support on carbon (Pt/C, JM), synthesis Pt/C and synthesis Pt3Cu1 alloy nanoparticles supported on carbon were compared. We confirmed that the synthesized Pt3-Cu1/C has high electrochemical performance than commercial Pt/C. It is expected to develop an electrocatalyst with high activity at low price by increasing the oxygen reduction reaction rate of the fuel cell.

• Resources Recycling
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• v.21 no.2
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• pp.34-40
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• 2012

$Pt_{10}$/C, $Pt_9Mn_1$/C, $Pt_7Mn_3$/C electrocatalysts for Polymer Electrolyte Membrane Fuel Cells(PEMFCs) were synthesized by reduction with HCHO and their activity as a oxygen reduction reaction(ORR) was examined at half cell. The electrochemical oxygen reduction reaction(ORR) was studied by using a glaasy carbon electrode through cyclic voltammetric curves(CV) in a 1 M $H_2SO_4$ solution. The ORR activities of $Pt_9Mn_1$/C were higher than $Pt_{10}$/C, $Pt_7Mn_3$/C. Also potential-current curves of $Pt_9Mn_1$/C at 0.9, 0.8, 0.7, 0.6V for 5minutes respectively were higher than $Pt_{10}$/C, $Pt_7Mn_3$/C. Physical characterization was made by using x-ray diffraction(XRD) and transmission electron microscope(TEM). The TEM images of $Pt_9Mn_1$/C, $Pt_{10}$/C catalysts showed homogenous particle distribution with particle size of about 2.7 nm, 3 nm respectively and then the XRD results showed that the crystalline structure of the synthesized catalysts are seen FCC structure.

• Journal of the Korean Electrochemical Society
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• v.11 no.3
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• pp.154-158
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• 2008

The synthesis of hollow ${Sb_93}{Pt_7}$ nanospheres smaller than 30 nm with a shell consisting of smaller nanoparticles, with an average particle size of ${\sim}$ 3 nm is reported. The formation of this alloy is driven by galvanic replacement reaction involving Sb nanoparticles and ${H_2}{PtCl_6} $ without need for any additional reductants. Further, the reaction proceeds selectively as long as the redox potential between two metals is favorable. The capacities of the hollow samples are 669 and 587mAh/g at rates of 1 and 7C, respectively, while those values for the nanoparticles are 647 and 480mAh/g at rates of 1, 7C, respectively. This result shows the significantly improved capacity retention of the hollow sample at higher C rates, indicating that high surface area of the hollow nanospheres makes the current density more effective than that for the solid counterpart.

• 한국전기화학회:학술대회논문집
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• 2003.07a
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• pp.189-192
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• 2003

In this work, we have prepared platinum catalyst by various methods, investigated fuel cell performance and compared performance with commercially available $20\%$ Pt supported on carbon (Pt/C) catalyst. We have found that Pt/C prepared by reduction of chloroplatinic acid in mixed solvent (water+ethylene glycol) gives better performance compared to that produced by reduction of aqueous chloroplatinic acid, which can be attributed to smaller catalyst particle size and lower agglomeration in the mixed solvent. We have also prepared a novel platinum electrocatalyst by depositing platinum on Nafion coated carbon powder and it shows great promise. The performance of electrode prepared using $20\%Pt$ onn Nafion coated carbon mixed with Pt/C was found to be higher than the performance of electrodes using commercially available $20\%$ Pt/C, up to a current density of about $1100mA/cm^2$. The cell voltages obtained were respectively 621 and 603mV, at a current density of: $1000mA/cm^2$, in a single cell using $0.25mgPt/cm^2$ and Nafion 10035 membrane at $80^{\circ}C$ using hydrogen/oxygen reactants at 1 atm pressure.