CO and CO/H2 electrooxidation on carbon supported Pt–Ru catalyst in phosphotungstic acid (H3PW12O40) electrolyte

An electrode-kinetic study of the oxidation of CO and CO/H2 mixtures on a Pt–Ru/C catalyst was carried out in phosphotungstic acid (PWA) electrolyte. The influence of temperature, CO partial pressure and proton concentration on the electrochemical oxidation rate was investigated. An apparent activation energy of about 50kJmol−1 was found for CO oxidation at 0.6V vs NHE. Fractional reaction orders close to 0.5 and −0.4 with respect to carbon monoxide and proton concentration, respectively, were observed. Tafel slopes were close to 136mVdec−1 at 70°C for both CO and CO/H2 oxidation. The PWA electrolyte appeared to promote the methanol electrooxidation by increasing the rate of water discharge at the electrode.