An Electrochemical Approach for Estimation of Intrinsic Active Area and Activation of Pt/C Nano‐catalysts

Abstract

AbstractA methodology has been developed for the estimation of intrinsic active area of Pt/C nano‐catalysts which is crucial for the evaluation of catalyst's utilization in a membrane‐electrode‐assembly (MEA). The evaluation was carried out by employing the H‐UPD and CO stripping methods for both a thin porous Pt/C‐Nafion film coated on a glassy carbon disk and a carbon paper electrode. The results demonstrate that the measured values of intrinsic active area (i.e., the extents of utilization) of Pt/C in Nafion ionomer films are identical at both glassy carbon (GC) and carbon paper surfaces from 2 to 330 μg‐Pt/cm2 loading. However, the measured active area is strongly dependent on the electrode support for the loadings greater than 330 μg‐Pt /cm2 where the carbon paper electrodes show much higher active areas. Three different pre‐activation methods have been adopted to activate all the Pt sites in the catalyst layer namely potential cycling and constant potential treatment at an applied potential of 0 or 1.2 V (RHE). These results demonstrate the necessity of such a simple and convenient pre‐operation activation treatment for Pt/C catalysts in MEA to assess their intrinsic active area towards the electrochemical reactions.