Comparison of ethanol and methanol oxidation in a liquid-feed solid polymer electrolyte fuel cell at high temperature

The electrochemical oxidation of ethanol and methanol in a liquid-feed solid polymer electrolyte fuel cell operating at 145 degrees C was investigated. A composite membrane made of Nafion ionomer and silica was fabricated in order to maintain the advantageous water-retention properties of these materials at high temperature. A pressurized cell (4 atm, anode; 5.5 atm, cathode) employing carbon-supported Pt-Ru (1:1) and Pt catalysts with a Pt loading of 2 mg cm(-2) was investigated. The direct methanol fuel cell showed a peak power density of about 240 mW cm(-2) at 0.6 A cm(-2) and 0.4 V. The power density approached 450 mW cm(-2) in the internal resistance- free polarization curve, and the methanol crossover rate was about 4 x 10(-6) mol min(-1) cm(-2). The direct ethanol fuel cell showed a maximum power density of about 110 mW cm(-2) at 0.32 V and 0.35 A cm(-2) with high selectivity toward CO 2 formation (approximate to 95%). (C) 1998 The Electrochemical Society. S1099-0062(97)12-118-6. All rights reserved.