Methanol-resistant cathodic oxygen reduction catalysts for methanol fuel cells

Author： Tributsch H. Bron M. Hilgendorff M. Schulenburg H. Dorbandt I. Eyert V. Bogdanoff P. Fiechter S.

ISSN： 0021-891X

Source： Journal of Applied Electrochemistry, Vol.31, Iss.7, 2001-07, pp. : 739-748

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Abstract

Efforts were made to simplify the structure of Ru-based catalysts, and to tailor industrially practicable methanol insensitive oxygen reduction catalysts both by thermolysis of Ru-carbonyls in organic solvents and by modified preparation techniques of Ru colloids. Selective catalysis was found to be essentially independent of the chalcogene (Se) used which, however, is a crucial factor for facilitating efficient electron transfer. All preparations contained Ru-metal particles of nm size, the surfaces of which were modified by carbonyl and carbido-carbonyl complexes or carbon compounds. The role of carbon as ligand to Ru clusters stabilizing the Ru interface against oxidation and in promoting catalytic electron exchange via nonbonding Ru d-states is theoretically analysed in a model calculation. An analogy is drawn to a biological Fe – only hydrogenase centre in order to discuss projected key experiments for optimizing reduction catalysis: the stabilization of small, inherently unstable catalytic metal clusters by CO or CN and their linking via electron bridges such as S and Se to electron reservoirs (metal colloids).