IMPREGNATION OF MICROPOROUS ELECTROCATALYST PARTICLES FOR IMPROVING PERFORMANCE IN AN ELECTROCHEMICAL FUEL CELL

摘要

A method is provided for treating electrocatalyst particles and using the treated electrocatalyst for improving performance in an electrochemical fuel cell. The treatment method comprises impregnating pores of the electrocatalyst particles with an impregnant wherein the pores comprise micropores which have an aperture size less than 0.1 micron. The impregnant is preferably ion-conducting and may comprise an organic acid, an inorganic acid, or a polymer. Alternatively, or in addition, the impregnant has an oxygen permeability greater than that of water. The method of impregnating the electrocatalyst particles preferably comprises the steps of contacting the electrocatalyst particles with an impregnant and subjecting the electrocatalyst particles to a vacuum and/or an elevated pressure above atmospheric pressure. The treated electrocatalyst particles are incorporated into an electrochemical fuel cell. The impregnant improves the mass transport properties for the movement of reactants and reaction products within the micropores of the electrocatalyst particles, thereby improving electrocatalyst utilization and electrochemical fuel cell performance for a fixed amount of electrocatalyst.