FORMIC-ACID OXIDATION IN A POLYMER ELECTROLYTE FUEL-CELL - A REAL-TIME MASS-SPECTROMETRY STUDY

The electro-oxidation of formic acid was studied in a direct-oxidation polymer-electrolyte fuel cell at 170 degrees C using real-time mass s pectrometry. The results are compared with those obtained for methanol oxidation under the same conditions. Formic acid was electrochemicall y more active than methanol on both Pt-black and Pt/Ru catalysts. The polarization potential of formic acid oxidation was ca. 90 to 100 mV l ower than that of methanol. The oxidation of formic acid was dependent on the water/formic acid mole ratio. The best anode performance was o btained using a water/formic acid mole ratio of similar to 2, In addit ion, Pt/Ru catalyst was more active than Pt-black for formic acid oxid ation. The mass spectrometric results showed that CO2 is the only reac tion product of formic acid oxidation. The results are discussed in te rms of possible formic acid oxidation mechanisms.