Papers by Keyword: Platinum Catalyst

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Authors: Eun Jung Park, Yun Ki Ko, Chu Sik Park, Kyung Soo Kang, Won Chul Cho, Ki Kwang Bae, Young Ho Kim
Abstract: Pt catalysts have been researched and used for HI decomposition. Specifically, the effects of supports and reduction temperature on metal dispersion were investigated in this paper. Metal dispersion was high measured, in the order of Pt/Al2O3, Pt/ZrO2, and Pt/SiO2. HI conversion results coincided with the metal dispersion. With effect on reduction temperature, Pt dispersion was measured as 2.9 %, 26 %, and 60 % each 1173K, 973K, and 773 K. In addition, HI conversion presented 7.8%, 16.3%, and, 19.4% respectively. Consequently, Pt dispersion, influenced by supports and reduction temperature was considered to be crucial role in HI conversion.
Authors: B. Babić, Velimir Radmilović, N. Krstajić, B. Kaludjerović
Abstract: Mesoporous carbon cryogel synthesized by sol-gel polycondensation and freeze-drying with specific surface area (BET) of 517 m2 g-1 was used as a catalyst support. Pt/C catalysts were prepared by a modified ethylene glycol method (EG). Transmission electron microscopy (TEM) images show that the dispersion of the catalyst is very uniform with a mean particle size of about 2.65 nm. Hydrogen oxidation reaction (HOR) was studied on Pt/C catalyst in 0.5 mol dm-3 HClO4 acid solution. It has been found that HOR appears as a reversible two-electron direct discharged reaction (Tafel slope for this reaction is ≈30mV dec-1) and that Pt/C catalyst exhibits a very high catalytic activity. However, the corresponding value of the exchange current density obtained by dividing the exchange current by the active surface area of Pt particles has the same order of magnitude as those for the HOR in acidic solution at single crystal and polycrystalline Pt.
Authors: Lj.M. Gajić-Krstajić, T.Lj. Trišović, B. Babić, Lj.M. Vračar
Abstract: The kinetics of oxygen reduction (ORR) on carbon cryogel supported Pt nanoparticles (Pt / C) in acid solution was studied using the rotating disk electrode technique. This electrocatalyst was prepared by a modified polyol synthesis method and characterized by transmission electron microscopies. The kinetics of ORR shows a significant enhancement at Pt nanoparticle surfaces as compared with the same reaction on polycrystalline Pt surface. The four-electron reduction, with a first-charge transfer-rate determining step, has been found to be operative. However, the specific activity of the Pt / C is similar to that of the polycrystalline Pt electrocatalyst.
Authors: Hee Soo Kim, Pil Kim, Young Geun Park, Jae Ho Lee, Kyung Hee Choi, Jong Heop Yi
Abstract: Mesoporous carbon (MCs) was synthesized using mesoporous silica as a template. Prepared mesoporous carbon materials were found to have high surface area and large pore volume with uniform pore size. Resulting materials showed a different pore arrangement from mesoporous silica templates. Pt catalysts supported on mesoporous carbon prepared were applied to an anode catalyst for Direct Methanol Fuel Cell (DMFC). Results indicate that a mesoporous carbon having 3-dimensional pore system (3D-MC) had higher catalytic activity than 2-dimensional one (2D-MC) due to a favorable pore structure in methanol electro-oxidation.
Authors: Pho Van Bui, Shun Sadakuni, Takeshi Okamoto, Kenta Arima, Yasuhisa Sano, Kazuto Yamauchi
Abstract: Our group has developed a novel abrasive-free planarization technique known as catalyst-referred etching (CARE). It can produce flat, undamaged, and smooth SiC surfaces with a root-mean-square roughness of less than 0.1 nm over a whole wafer. This study investigates the etching mechanism of CARE by performing X-ray photoelectron spectroscopy (XPS) measurements to determine the termination species of CARE-processed SiC surfaces. We compared XPS spectra of a CARE-processed surface with those of an as-received SiC surface that had been treated with 50% HF solution. XPS spectra of the CARE-processed wafer contain the F 1s core level, whereas those of an as-received SiC wafer surface did not. This indicates that F anions play an important role in the etching process of CARE.
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