Ethanol-Tolerant Oxygen Reduction Reaction (ORR) Cathodes for Direct Ethanol Fuel Cell Applications

The catalytic activity of the ruthenium catalysts dispersed onto carbon powder for the ORR in an acid medium with and without ethanol was studied. It was found that the Ru/C catalyst cathode exhibited a high tolerance to ethanol and has a high degree of selectivity for the ORR in the presence of ethanol. Thus, its catalytic activity towards the ORR is not significantly affected by the presence of ethanol. The onset potential of the ORR on Ru/C increases very slightly by 60, 62 and 68 mV for the electrolytes containing 0.5M H2SO4 with respectively 0.125M, 0.250M and 0.500M C2H5OH solutions. This reduction of the onset potential of the ORR activity of the Ru/C catalyst from its value without ethanol to its value in the presence of the ethanol is about ten times smaller than those on Pt-based catalysts (i.e. an increase of 590 mV in onset potential of the ORR with a Pt/C catalyst in a 0.5M H2SO4 + 0.125M C2H5OH solution). Furthermore, when tested as cathode material in a DEFC, the Ru/C catalyst presented notable current density vs. fuel cell voltage characteristics at 80 and 90{degree sign}C.