Electrochemical Investigation of Pt-Co/MWCNT as an Alcohol-Tolerant ORR Catalyst for Direct Oxidation Fuel Cells

摘要

In this study, we investigated the behavior of a 30% Pt70-Co30/MWCNT electrocatalyst as oxygenreduction reaction (ORR) material in acid electrolyte without and with liquid fuels. Thecharacterization was performed by rotating ring-disc electrode (RRDE) and electrochemical impedancespectroscopy (EIS). In the absence of organic molecules, the ORR on the alloy proceeds via a 4- electron transfer mechanism, with a negligible production of hydrogen peroxide, as indicated by theRRDE measurements. In the presence of the different liquid fuels (ethylene glycol, ethanol or 2- propanol), the alloy shows a high degree of tolerance, although this characteristic is dependent on thechemical composition of the molecule. The EIS measurements in solutions containing organicmolecules suggest that at high polarization potentials, the competitive interaction of oxygen reductionand liquid fuels oxidation at the alloy catalytic sites leads to a faster reaction, as shown by the smallercharge transfer resistances (Rct) obtained from Nyquist plots, compared to the Rct values withoutorganic molecules. The results obtained from the Pt-Co/MWCNT electrocatalyst are compared to thoseof a commercial Pt/C cathode.