II International Symposium on Carbon for Catalysis ABSTRACTS

OP-<strong>II</strong>-9
INFLUENCE OF THE CARBON SUPPORT ON THE PREPARATION OF HIGHLY
ACTIVE RUTHENIUM-SELENIUM CATALYST FOR THE ELECTROREDUCTION
OF OXYGEN
Bogdanoff P., Dorbandt I., Zehl G., Fiechter S.
Hahn-Meitner-Institut Berlin, 14109 Berlin, GlienickerStr. 100, Germany
e-mail: Bogdanoff@hmi.de
Presently, metallic platinum nano-particles (about 2-5 nm), which are deposited on suitable
carbon supports, are exclusively employed as catalysts in Polymer Electrolyte Membrane
(PEM) fuel cells. For a long time the carbon support was only considered as a chemical inert
and electrical conductive matrix, which enables the formation of porous gas diffusion
electrodes with a high dispersion of the expensive noble metal catalyst. However, in the last
years international research activities have been revealed that the morphology and the surface
chemistry of the carbon support influences significantly the formation and the characteristic
of the deposited catalytic nano-particles as well as the catalytic activity of the finally
composed gas diffusion electrode. Therefore, in order to enhance the electrochemical
efficiency of platinum catalysts in PEM-FCs investigations have been focused on the
development of more suitable carbon supports and its selective surface modification.
However, the application of platinum as a cathode catalyst for the electroreduction of oxygen
in PEM-FCs exhibits some significant drawbacks. An increasing demand of platinum causing
increasing metal prizes could impede the widespread use of PEM FCs as mass product. Other
disadvantages are the high overvoltage of the cathode reaction, migration and aggregation of
platinum particles and the missing selectivity, which leads to effects of toxification and of
depolarization by methanol in Direct Methanol Fuel Cells DMFC. Therefore, alternative
catalysts are required for the further development of PEM fuel cell technology.
This contribution presents our results on the preparation and characterisation of a rutheniumselenium-based
material onto different carbon supports, which shows high and stable activity
towards oxygen reduction in acidic media. Thermal decomposition of Ru 3 (CO) 12 in organic
solvents, chemical reduction of various ruthenium salts and colloidal techniques were tested
in order to prepare carbon supported ruthenium-particles in the nanometer scale. It has been
shown that the growth of ruthenium particles and its electronic coupling to the carbon support
is influenced by the surface chemistry and the pore size distribution of the applied carbon.
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