ELECTROCHEMICAL ENHANCEMENT OF A CATALYTIC REACTION IN AQUEOUS-SOLUTION

THE rates of many heterogeneous catalytic reactions between gaseous ad sorbates on metal surfaces supported on solid electrolytes can be incr eased by applying a potential to the metal(1-8). This phenomenon, whic h has been reported previously at temperatures of 250-750 degrees C, h as been shown(9) to be due to the electrochemically induced spillover of ions from the support onto the catalyst surface; the ions then act as promoters for the catalytic reaction. Here we report that a similar effect can be observed in aqueous solution at ambient temperatures. W e studied the oxidation of H-2 on a platinum/graphite electrode immers ed in aqueous KOH. Application of a positive potential of 1-2 V to the Pt electrode increased the rate of H-2 oxidation by up to 500%. We de duce that hydroxide ions are acting as promoters, and find that each i on supplied to the catalyst causes the oxidation of up to 20 hydrogen atoms. This kind of rate enhancement for heterogeneous catalytic react ions in solution may be of considerable technological value, for examp le in the electrochemical treatment of toxic organics(10) or the gener ation of useful industrial chemicals(4).