Application of the hanging meniscus rotating disk electrode method to oxygen reduction on platinum in H/sub 3/PO/sub 4/ (fuel cells)

Results obtained using the hanging meniscus rotating disk electrode (HMRDE) method are compared with those obtained using the standard RDE method for the oxygen reduction reaction on platinum in H/sub 3/PO/sub 4/ fuel cells at room temperature. Cyclic voltammograms and limiting current curves obtained by the HMRDE method are similar, but not identical, to those obtained by the standard method. A slight shape change is observed in the limiting current curves, and nonlinear Tafel plots are obtained for the HMRDE method. While the linear relationship between i/sub l/ and omega /sup 1/2/ described by the Levich equation is maintained, the slope is reduced and a small, positive intercept is present. Discrepancies between the two methods seem to be related to the different hydrodynamics involved with the hanging meniscus. In spite of the discrepancies, the HMRDE method shows some promise for determining comparative kinetics at elevated temperature (200 degrees C).>