Lanthanide–Platinum Intermetallic Compounds as Anode Electrocatalysts for Direct Ethanol PEM Fuel Cells

Abstract

The electrochemical stability and electrocatalytic performance in ethanol oxidation of a new class of anode electrocatalysts is presented. Nanopowders of the Laves-phase intermetallic compounds Ln Pt2 (Ln=Ce,Pr) were utilized to exploit the strong oxidizing power of tetravalent lanthanides in an anode electrocatalyst. These nanopowders are stable in the environment of the anode of a polymer electrolyte membrane (PEM) fuel cell. Steady-state polarization curves in an operating PEM fuel cell demonstrate that the new electrocatalysts are active toward the electro-oxidation of ethanol. The new electrocatalysts exhibited ca. 225 mV more overpotential than PtRu at a given current density based on the total electrocatalyst surface area in the anode, but this may be due to issues with particle size and electrode structure. Analysis of the anode effluent with on-line gas chromatography showed that two-electron electro-oxidation to acetaldehyde was the main reaction pathway at potentials of interest and implied that ethanol adsorbs without C-C bond cleavage through the oxygen in the hydroxyl group. © 2006 The Electrochemical Society.