Study of the Exchange Current Density for the Hydrogen Oxidation and Evolution Reactions

The exchange current density for the hydrogen oxidation/evolution reactions was determined in a proton exchange membrane fuel cell. Ultralow Pt-loaded electrodes were used to obtain measurable kinetic overpotential signals ( at ). Using a simple Butler–Volmer equation, the exchange current density and transfer coefficient were determined to lie within the range of and 0.5–1, respectively. Due to the fast kinetics, no measurable voltage losses are predicted for pure- proton exchange membrane fuel cell applications when lowering the anode Pt loadings from its current value of to the automotive target of .