Impedance studies on direct methanol fuel cell anodes

The processes taking place in direct methanol fuel cell anodes are characte rized by ac impedance spectroscopy. Under conditions of practical interest, i.e., low methanol stoichiometry factors, the kinetic and the mass-transpo rt resistance give rise to two well-resolved semicircles in the Nyquist plo t. When mass-transport limitations are excluded, inductive loops occur in t he complex plane which are interpreted in terms of the most widely accepted reaction mechanism for methanol electrooxidation. A simple equivalent circ uit is used to model this impedance behaviour. (C) 1999 Elsevier Science S. A. All rights reserved.