KINETIC-STUDY OF ELECTROCHEMICAL REACTIONS AT CATALYST-RECAST IONOMERINTERFACES FROM THIN ACTIVE LAYER MODELING

The objective of the following study was to test proton exchange membr ane fuel cell catalysts. A mixture of supported catalyst and re ast io nomer (Nafion(R)) was deposited on a rotating disc electrode (RDE). Th e resulting thin active layer was immersed in a dilute sulphuric acid solution. The RDE technique allows correction of mass transfer limitat ion in solution. To calculate the kinetic parameters from the current- potential relation, a mathematical model was written taking into accou nt gas diffusion, ohmic drops and interfacial kinetics within the thin layer. Analytic and/or numerical expressions for the effectiveness fa ctor and for the current-potential relation were obtained. The oxygen reduction reaction at various Pt/C-recast Nafion(R) interfaces demonst rates the validity of this test procedure.