Nonfaradaic Electrochemical Modification of the Catalytic Activity of Pt‐Black Electrodes Deposited on Nafion 117 Solid Polymer Electrolytes

Abstract

The kinetics of oxidation by gaseous were investigated on a Pt‐black catalyst film also serving as a working electrode in a Nafion 117 solid polymer electrolyte cell. The Pt‐covered side of the Nafion 117 membrane was exposed to the flowing mixture and the other side was in contact with a 0.1 M KOH aqueous solution with an immersed Pt counterelectrode. It was found that the applied current and the catalyst‐electrode potential affect the catalytic rate of oxidation in a very pronounced and reversible manner. Positive currents enhance the rate of oxidation by up to 2000%. The increase in the rate of oxidation is up to 300 times larger than the electrochemical rate, I/2F, of oxidation. This shows that the catalytic properties of the Pt film are significantly modified by varying catalyst potential, as also manifested by the observed potential‐induced change in the functional dependence of the catalytic rate on the partial pressures of and . This novel application of solid polymer electrolytes to act as electrochemically activated catalyst supports, and thus promote and control heterogeneous catalytic reactions, is of considerable theoretical and possibly practical interest.