Methanol crossover effects on cathode potential and performance of a direct methanol fuel cell

Abstract

Characteristic for a Direct Methanol Fuel Cell (DMFC), using a Nafion® membrane as electrolyte is a strong crossover of methanol and carbon dioxide to the cathode, which depends on factors like methanol concentration, current density and temperature. A mixed potential is observed at the cathode as a result of an equilibration between oxygen reduction and methanol oxidation. The potential effects are monitored as function of time and current density, using a dynamic hydrogen electrode (DHE) attached to the Nafion membrane. Besides methanol oxidation at the cathode, a chemical reaction between methanol and oxygen at the interface of the cathode takes place. The concentration of soluble intermediates formed during fuel cell operation is measured and the yield, as the number of electrons obtained per molecule is determined.