凯发_Seong Ihl Woo

Speaker-Seong Ihl Woo

Seong Ihl Woo
Korea Adv Inst Sci & Technol, Korea

Education
• Ph.D. Chem. Eng. 1983 University of Wisconsin-Madison, Thesis; Vibration spectroscopy of immobilized cobalt and rhodium carbonyl used to effect the catalytic hydroformylation of propylene
• M.S. Chem. Eng. 1975 Korea Advanced Institute of Science, Seoul, Korea, Thesis; Thermal degradation of poly(vinylchloride)
• B.S. Chem. Eng. 1973 Seoul National University, Seoul, Korea
Research Career
2008 Visiting Professor: Department of Chemistry, University of Tokyo
1985-Present Professor: Department of Chemical and Biomolecular Engineering, Korea Advanced Institute of Science and Technolog
2001-2010 Director: Center for Ultramicrochemical Process Systems, Korea Advanced Institute of Science and Technology
1990-1991 Humboldt Research Professor: Surface Reaction Laboratory, Max Planck Institute (Fritz-Haber-Inst.), Berlin, Germany
1989 Visiting Professor: Research Laboratory of Resource Utilization, Tokyo Institute of Technology
1983-1985 3M Company Postdoctoral Fellow: Department of Chemistry, University of Toronto, Worked with Professor G.A. Ozin on the preparation and characterizations of metal cluster catalysts via metal atom deposition technique
1978-1983 Research and Teaching Assistant: Department of Chemical Engineering, University of Wisconsin-Madison
1975-1978 Research Engineer: Polymer Laboratory, Korea Institute of Science and Technology
Research Statement
Dr. Seong Ihl Woo is a professor in Korea Advanced Institute of Science and Technology, attending as an advisor in the Graduate school of EEWS, Bio-molecular Chemical Engineering, and Department of Chemistry. Dr. Woo got “the National Medal of Science and Technology” on 2001, “2000 Outstanding Intellectuals of the 21st century” on 2012 from IBC, and “Who’s who in the World” on 2014. Currently, Dr. Woo’s researches focus on catalysts for fuel-cell, solar fuel materials such as catalysts for CO2 reduction, catalysts for water splitting (hydrogen evolution, and water oxidation), and materials for transparent conductive oxide. He worked as an editorial board member of ACS combinatorial science, ChemSUSChem, Catalysis Letter, and Topics in Catalysis.

Title：Morphological and dimensional effect of the graphene on high performing oxygen reduction reaction catalysts in acidic media

SymposiumB10 Fuel Cells

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Abstract

N-doped graphene is considered as next generation oxygen reduction reaction (ORR) catalysts for fuel cells due to its ideal uniqueness of high surface area, electrical conductivity, prolonged stability and low cost. Contrary to the general belief, however, graphene catalysts have shown poor catalytic activities compared with those of other carbon–based catalysts. It is mainly attributed to the fact that underlying mechanism of the graphene catalysts has been only insufficiently identified, preventing the rational design of high-performing catalysts. Here, we show that the first electron is transferred into O2 molecules at the outer Helmholtz plane (ET-OHP) over a long range. This is in sharp contrast to the conventional belief that O2 adsorption must precede the ET step and thus that the active site must possess as good an O2 binding character as that which occurs on metallic catalysts. Based on the ET-OHP mechanism, the location of the electrode potential dominantly characterizes the ORR activity. Accordingly, we demonstrate that the electrode potential can be elevated by reducing the graphene size and/or including metal impurities, thereby enhancing the ORR activity, which can be transferred into single-cell operations with superior stability. Moreover, the dimensionality of graphene catalysts is sequentially tuned from sheets (2D) to ribbons (1D) and to dots (0D), and then the accompanying changes in terms of physical and electrochemical properties are investigated. In ultraviolet photoelectron spectroscopy, an increment in electropotential is measured as the dimensionality of the graphene catalysts decreases, of which the result infers the enhanced kinetics of the electron transfer from the graphene catalysts to O2 (electropotential: 0D > 1D > 2D). However, ORR performance does not follow the order of electropotential, and the graphene ribbons show the best activity among the prepared graphene catalysts (ORR activity: 1D > 0D > 2D). Further electrochemical impedance spectroscopy studies demonstrate that ORR kinetics is primarily determined by charge transfer rates in the fabricated graphene electrodes, which are strongly related to the electrode configurations and thus also to the length–to–width ratios of the graphene catalysts. This suggests the importance of void channels in the fabricated graphene electrode, which have not previously been considered significantly as a factor for improving ORR activity on the graphene catalysts.