Non-faradaic electrochemical modification of catalytic activity .11. Ethane oxidation on Pt

The rate of ethane oxidation on polycrystalline Pt catalyst films deposited on 8 mol% Y2O3-stabilized ZrO2, an O2- conductor, can be reversibly enhanced by up to a factor of 20 by varying the potential of the Pt film. The rate increase is typically a factor of 200 higher than the electrochemically controlled rate of supply of promoting oxide ions. Electrochemical oxygen removal from the Pt catalyst surface also enhances the catalytic rate by up to a factor of 7. In this case the rate increase is typically a factor of 20 higher than the electrochemically controlled rate of oxygen removal. The ethane oxidation activation energy varies linearly by a factor of 3 with varying catalyst potential, leading to the appearance of the compensation effect. The observed pronounced promotional phenomena are discussed on the basis of the reaction mechanism, previous electrochemical promotion studies and recent TPD and XPS investigations. (C) 1997 Academic Press.