Preparation and influence of performance of anodic catalysts for direct methanol fuel cell

This research aims to increase the utilization of platinum-ruthenium alloy (Pt-Ru) catalysts and thus to lower the catalyst loading in anodes for methanol electrooxidation. The DMFCs anodic catalysts, Pt-Ru/C, were prepared by chemical reduction with a reducing agent added in hot solution under inert gases or air, and in cold solution under inert gases. The catalysts were treated at different temperatures. Their performance were tested by cyclic voltammetry and potentiostatic polarization with a powder microelectrode from them in 0.5 mol/L CH₃OH and 0.5 mol/L H₂SO₄ solution, and their structures and micro-surface images were determined and observed by X-ray diffraction and transmission electron microscopy, respectively. The catalyst prepared in inert gases showed a better catalytic performance for methanol electrooxidation than that in air. It resulted in a more homogeneous distribution of the Pt-Ru alloy in carbon. Its size is small, about 4.5 nm. The catalytic performance is affected by different orders at reducing agent added. The performance of catalyst prepared by adding the reductant constant temperature of the solution is better than that prepared by adding it in the solution at 0°C and then heated it up to the reducing temperature. The catalyst structure was modified, and there was an increase in the conversion of ruthenium into the alloyed state and an increase of particle size with the increase of heat treatment temperature. Its stability was improved after heat treatment.