CO and methanol oxidation at platinum-tin electrodes

Abstract

Electrooxidation of dissolved CO and methanol at platinum-tin electrodes with different phase composition (a two-phase Sn/Pt-catalyst, Pt-Sn alloy, and Pt3Sn intermetallic compound) is studied. All studied catalysts show higher catalytic activity in the CO oxidation at lower potentials (0.3–0.5 V against reversible hydrogen electrode (RHE)), as compared with platinum; no catalysis is observed at higher potentials (0.7 V); moreover, inhibiting is observed in some cases. The catalyst with the most strongly ordered structure (Pt3Sn) demonstrated the highest catalytic activity; however, it appeared being less stable against oxidation at potentials more positive than 1.0 V. Catalytic effects were practically absent in the CO-adsorbate oxidation process. The sequence of catalyst activities in the methanol oxidation process differed from that in the CO oxidation; in particular, Pt3Sn appeared being the least active. The observed difference can be associated with the difference in the CO and methanol adsorption mechanisms. The effect of the carbonaceous support dispersion on the current-voltage curves is discussed.