Browsing by Author "Chen, Chung-Shou"

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Effects of the PdO nanoflake support on electrocatalytic activity of Pt nanoparticles toward methanol oxidation in acidic solutions
(2012-06-15)
Chen, Chung-Shou
;
Pan, Fu-Ming
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We prepared PdO nanoflake thin films on carbon cloths by reactive sputtering deposition, and studied electrocatalytic performance of Pt nanoparticles electrodeposited on the PdO thin film in methanol oxidation reaction (MOR) in acidic media. The PdO nanoflake thin film exhibits a cyclic voltamperometric (CV) behavior similar to metallic Pd electrodes because a metallic Pd surface layer is formed on the PdO thin film electrode under the CV measurement condition. The nanoflake morphology of the PdO electrode provides a large surface area for Pt nanoparticle loading, resulting in a large electrochemical active surface area (ESA). The Pt/PdO electrode has a high electrocatalytic activity toward MOR, and the good electrocatalytic performance of the Pt/PdO electrode is ascribed to a high CO tolerance and the large ESA. We suggest that the high CO tolerance of the catalyst on the Pt/PdO electrode is a result of the synergism of the bifunctional mechanism and the electronic effect. XPS analyses indicate that negative charge transfer occurs from the PdO support to the Pt nanoparticles, indicating the presence of the electronic effect. Pt nanoparticles on the PdO support can greatly alleviate the nanoflake damage during the CV measurement, which results from anodic dissolution of metal Pd from the PdO support in acidic media. (C) 2012 Elsevier B.V. All rights reserved.
Electrocatalytic activity of Pt nanoparticles deposited on porous TiO(2) supports toward methanol oxidation
(2009-09-28)
Chen, Chung-Shou
;
Pan, Fu-Ming
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Porous TiO(2) thin films were prepared on the Si substrate by hydrothermal method, and used as the Pt electrocatalyst support for methanol oxidation study. Well-dispersed Pt nanoparticles with a particle size of 5-7 nm were pulse-electrodeposited on the porous TiO(2) support, which was mainly composed of the anatase phase after an annealing at 600 degrees C in vacuum. Cyclic voltammetry (CV) and CO stripping measurements showed that the Pt/TiO(2) electrode had a high electrocatalytic activity toward methanol oxidation and an excellent CO tolerance. The excellent electrocatalytic performance of the electrode is ascribed to the synergistic effect of Pt nanoparticles and the porous TiO(2) support on CO oxidation. The strong electronic interaction between Pt and the TiO(2) support may modify CO chemisorption properties on Pt nanoparticles, thereby facilitating CO oxidation on Pt nanoparticles via the bifunctional mechanism and thus improving the electrocatalytic activity of the Pt catalyst toward methanol oxidation. (C) 2009 Elsevier B.V. All rights reserved.
Electrocatalytic activity of Pt nanoparticles deposited on porous TiO2 supports toward methanol oxidation
(2009-09-28)
Chen, Chung-Shou
;
Pan, Fu-Ming
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Porous TiO2 thin films were prepared on the Si substrate by hydrothermal method, and used as the Pt electrocatalyst support for methanol oxidation study. Well-dispersed Pt nanoparticles with a particle size of 5-7 nm were pulse-electrodeposited on the porous TiO2 support, which was mainly composed of the anatase phase after an annealing at 600 degrees C in vacuum. Cyclic voltammetry (CV) and CO stripping measurements showed that the Pt/TiO2 electrode had a high electrocatalytic activity toward methanol oxidation and an excellent CO tolerance. The excellent electrocatalytic performance of the electrode is ascribed to the synergistic effect of Pt nanoparticles and the porous TiO2 support on CO oxidation. The strong electronic interaction between Pt and the TiO2 support may modify CO chemisorption properties on Pt nanoparticles, thereby facilitating CO oxidation on Pt nanoparticles via the bifunctional mechanism and thus improving the electrocatalytic activity of the Pt catalyst toward methanol oxidation. (C) 2009 Elsevier B.V. All rights reserved.
Electrocatalytic activity of Pt nanoparticles on a karst-like Ni thin film toward methanol oxidation in alkaline solutions
(2011-05-18)
Chen, Chung-Shou
;
Pan, Fu-Ming
;
Yu, Hsin-Jung
;
材料科學與工程學系
;
Department of Materials Science and Engineering
The study prepared rugged Ni thin films for the study on electrocatalytic methanol oxidation reaction (MOR) in alkaline solutions. The rugged Ni thin film has a karst-like morphology, which provides a large surface area for Pt nanoparticle loading by pulse electrodeposition. Cyclic voltammetry measurements showed that the Pt/karst-Ni electrode had a high electrocatalytic activity toward MOR and CO tolerance in the KOH electrolyte. Ni(OH)(2) formed on the Ni support during the potential scan can enhance CO tolerance of Pt nanoparticles via the bi-functional mechanism. The Langmuir-Hinshelwood and the Eley-Rideal mechanisms are used to elucidate the role of OH surface groups on the Ni support and OH- ions in the electrolyte, respectively, in the enhancement of the CO tolerance. XPS analysis indicates that negative charges transfer from the Ni support to Pt nanoparticles. The electronic interaction may modify adsorption properties of CO adspecies on the Pt catalyst; the modification allows easy CO electro-oxidation by OH species surrounding the Pt nanoparticles, either from the Ni support or from the alkaline solution. The synergistic effect of the bifunctional mechanism and the electronic interaction makes the Pt/karst-Ni structure a good catalytic electrode for MOR in the KOH solution. (C) 2011 Elsevier B.V. All rights reserved.
Electrocatalytic activity of Pt nanoparticles on karst-rock shaped Ni thin films toward methanol and ethanol oxidation in alkaline solutions
(2010)
Chen, Chung-Shou
;
Pan, Fu-Ming
;
Yu, Hisn-Jung
;
材料科學與工程學系
;
Department of Materials Science and Engineering
We prepared Ni thin films with a karst-rock topography on the Si substrate and used the thin film as the electrocatalyst support for the study of methanol and ethanol oxidation in alkaline media. Well-dispersed Pt nanoparticles were pulse-electrodeposited on the rugged Ni thin film, which provided a very large surface for the Pt loading. The cyclic voltammertry (CV) showed that the Pt/Ni electrode had a high electrocatalytic activity toward methanol oxidation compared with blanket Pt. Nanosized Pt particles electrodeposited on the rugged surface of the Ni thin film provide a large amount of electrocatalytic sites for methanol oxidation. Hydroxyl surface groups bound on the Ni karst-rock nanostructures in the alkaline solution may greatly enhance CO electro-oxidation in terms of the bifunctional mechanism. The study demonstrates that the karst-rock shaped Ni thin film is a potential candidate as the Pt electrocatalyst support for direct methanol alkali fuel cells.