Kinetics of formic acid oxidation in advanced porous electrodes

The electrochemical oxidation of formic acid HCOOH at porous PTFE-bonded platinum-carbon electrodes in acidic electrolyte has been studied using the AC-impedance method. A reaction sequence based on known details of this process was transferred into an equivalent circuit which was used to simulate successfully the measured impedance data. The results confirm earlier data obtained with smooth platinum electrodes and allow, for the first time, a correlation between the electrode overpotential and the contribution of the various reaction steps. Further improvements of the porous electrode based on these results are suggested.