ELECTROCHEMICAL PROMOTION OF ETHYLENE OXIDATION ON PT CATALYST FILMS DEPOSITED ON CEO2

It was found that the activity of Pt catalyst films interfaced with Ce O2 disks can be reversibly modified upon application of constant curre nts or potentials through the cell C2H4, O-2, CO2, H2O, Pt \CeO2\Au, C 2H4, O-2, CO2, H2O Negative current (or potential) application causes up to threefold enhancement in the rate of ethylene oxidation at tempe ratures 450-510 degrees C. The rate increase is up to 3 X 10(5) times higher than the rate, I/2F, of oxygen-ion transport through The mixed- conducting CeO2 support, if this was a pure ionic conductor. The obser ved nonfaradaic modification of catalytic activity is qualitatively ve ry similar to that obtained when using pure anionic conductors, e.g., Y2O3-stabilized-ZrO2 and can be rationalized similarly, i.e., by consi dering the electrochemical induced changes in the work function of the catalyst and the concomitant changes of coverages and dipole moments of adsorbates. Apart from theoretical interest, the results are import ant in view of the current technological applications of ceria in auto motive exhaust catalysts.