Characterization of platinum-based supported catalysts for the direct methanol fuel cell

The specific surface area of Pt electrodeposits, dispersed in polyaniline and on carbon powders, were estimated from the extent of hydrogen and carbon monoxide adsorption. From these values and a knowledge of the Pt loading, a model analysis was carried out to calculate the Pt distribution on the substrate. A comparison was made between these results slid those obtained from direct observations by SEM or TEM. TEM observations revealed an heterogeneous distribution of Pt deposits throughout the porous electrode; the Pt surface morphology was, however, not greatly influenced by the substrate. Methanol oxidation was performed as a test reaction. The catalytic electroactivity for methanol oxidation decreased significantly with increase of the specific surface area; on the other hand, the activity of a smooth Pr electrode is much lower than that of a slightly dispersed Pt electrode.