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Carbonized aerogel-platinum composites as fuel cell electrocatalysts: some electrochemical and surface effects

Pages: 017-024

Siyu Ye^a, Ashok K. Vijh^a,* and Le H. Dao^b

^aIREQ Institut de Recherche d'Hydro-Quebec, 1800 Boul. Lionel-Boulet, Varennes, Quebec, J3X 1S1, Canada
^bLaboratoire de Recherche sur les Materiaux Avances, INRS-Energie et Materiaux, 1650 Boul. Lionel-Boulet, C.R 1020, Varennes, Quebec, J3X 1S2, Canada

Received October 2, 1997; received in revised form January 26, 1998

Abstract: Aerogels are a unique class oflow density foams with many fascinating properties. To use their interesting morphological and chemical properties, an aerogel material, namely polyacrylonitrile aerogel, has been prepared and investigated as a substratefor a fuel cell electrocatalyst. The incorporation ofthe noble metal, platinum, into the carbonized polyacrylonitrile aerogels for obtaining the carbonized aerogel-platinum electrocatalyst was accomplished in two ways. The first one introduces platinum by means ofsoluble inorganic or organometallic platinum compounds after the aerogel is carbonized. The second method involves the mixture ofa soluble inorganic or organometallic compound with a polyacrylonitrile solution during aerogel formation. A detailed characterization of these electrocatalysts was conducted by combining microscopic methods, XPS and electrochemical approaches. Special metal-support interaction was concluded to exist: it involves the formation ofcharge transfer complex between platinum and pyridine type nitrogen atoms ofPAN support. This interaction is considered to lead to the enhancement ofthe catalytic activity and the improvement oflong time stability ofthis electrocatalyst. These carbonized aerogel-platinum composites were used as electrode materials for the oxygen reduction. Comparison ofthe behavior ofthe carbonized aerogel-platinum composites with that ofa bulk platinum electrode is provided.

Keywords: Aerogel, fuel cell, electrocatalyst, metal-supportinteraction, XPS