Enhanced Methanol Oxidation Using Polymer-Incorporated Rough Pt Electrodes

We study the methanol oxidation reaction (MOR) on very rough Pt surfaces. We develop an electrodeposition method yielding Pt electrodes with high roughness factors (R_f > 80), controlled by varying the electrodeposition time or by polymer codeposition. These rough electrodes exhibit a linear MOR response at potentials up to 1.4 V versus RHE, in contrast to the hysteretic behavior reported in numerous prior studies. This effect is found in both acidic and basic electrolytes. Studies show that increased surface roughness increases the surface concentration of methanol, thereby inhibiting the formation of Pt oxides at higher potentials, which are known to poison the subsequent methanol oxidation activity. The potential at which methanol oxidation poisoning occurs is found to be logarithmically dependent on the bulk methanol concentration, with varying slopes in acidic and basic media. The origin of different sensitivities in basic relative to acidic electrolytes is found to be the result of different reaction orders with respect to methanol. This study provides methods to enhance the rate of organic molecule oxidation at electrode surfaces that can be applied to both electrosynthesis and direct methanol fuel cell applications.