REDUCTION OF OXYGEN IN AN ACIDIC METHANOL OXYGEN (AIR) FUEL-CELL - AN ONLINE MS STUDY

The reduction of oxygen was studied with online mass spectroscopy on 5% Pt/Norit BRX and on 20% FePP(NO2)4/RB PTFE-bonded gas diffusion electrodes. The performance of the catalysts was analysed under conditions of an acidic methanol/oxygen (air) fuel cell cathode in the presence of methanol in solution. Following the mass signal m/e = 32 for oxygen it can be shown that FePP(NO2)4 catalyses the oxygen reduction selectively. In contrast, on the Pt-carbon catalyst methanol is oxidized to CO2 (m/e = 44) thus establishing a mixed potential and an additional consumption of methanol. Furthermore, it can be demonstrated that on a platinum-carbon electrode the methanol oxidation is catalysed in the presence of oxygen, shifting the onset potential of CO2 production 100 mV more cathodic.