Platinum–Glass Composite Electrode for Fuel Cell Applications

Thin-film electrodes for a low-power direct methanol fuel cell DMFC were prepared by incorporating carbon-supported Pt nanoparticles Pt/C into a silicon dioxide glass matrix. The SiO2 matrix was prepared via a sol-gel technique where tetraethyl orthosilicate TEOS was hydrolyzed by H2O in the presence of methanol. The Pt/C was stirred into the sol and the resulting mixture was applied to a glass membrane substrate and cured. The resulting films were 2 m thick. Scanning electron microscopy SEM images indicate that the Pt/C was well dispersed, forming glass-separated conductive islands with sheet resistances in excess of 5000 / . The catalyst islands were interconnected into a conductive sheet by electrolessly depositing platinum from an aqueous plating bath. The Pt/C–SiO2 glass composite thin-film electrodes showed high methanol oxidation peak currents of 180 mA/cm2 when immersed in 0.5 M H2SO4, 0.5 M methanol electrolyte. The composite electrode was also applied to the anode of a 1 cm2 passive DMFC and compared to an equivalent passive DMFC with a traditional Nafion-based Pt anode electrode with 10 M MeOH at room temperature. The composite electrode DMFC showed a 50 mV higher open-circuit voltage than the Nafion electrode cell, and the current density was also modestly improved. © 2007 The Electrochemical Society. DOI: 10.1149/1.2790703 All rights reserved.