Porous Carbon Gas Diffusion Electrodes

Abstract

Porous carbon materials of widely differing properties were evaluated as gas diffusion fuel electrodes. The fuel gases were hydrogen, ethane, propane, and isobutane. Graphitized electrodes performed as well as nongraphitized electrodes. Performance of carbons with larger pore diameters could be improved as much as tenfold by wetproofing or by operating at high enough gas pressure to cause bubbling; however, the ultimate concentration polarization limitations appeared related only to the micropore structure. A simple method of measuring the micropore volume was developed. Limiting current densities with hydrocarbons were substantially less than with hydrogen under identical cell conditions. Chemical attack, including electrochemical oxidation of some of the carbons was observed.