Ruthenium selenide catalysts for cathodic oxygen reduction in direct methanol fuel cells

The oxygen reduction reaction in sulphuric acid on commercial carbon supported platinum and ruthenium catalysts as well as on a home-made carbon supported ruthenium selenide catalysts (RuSe _x /C) was investigated. The RuSe _x /C catalysts were synthesised using similar procedures to those found in the literature. A dependency of H₂O₂ formation on the selenium content was found using the thin-film rotating ring disc electrode technique, namely that the H₂O₂ formation in the typical operation range of a Direct Methanol Fuel Cell (0.7-0.4 V) on Pt/C is below 1% and 1-4% on Ru/C and RuSe _x /C catalysts. Finally for comparing the intrinsic activities of the catalysts the electrochemically active surface areas were determined in-situ by means of copper underpotential deposition. Our results indicate a comparable activity of the present RuSe _x /C catalyst to commercial Pt/C if the activities are related to the electrochemical active areas.