Electrochemical Pt surface area EPSA

Pt Catalyst-Coated Electrode Surface to Obtain the Electrochemical Pt-Surface Area (EPSA) 189... 

In fuel cell testing and diagnosis, CV is used to determine the electrochemical Pt surface area (EPSA) of a catalyst layer, and LSV is used to evaluate and monitor fuel crossover. For these methods, pure H2 and pure inert N2 or He are passed over the anode and the cathode, respectively. The anode is used as both the reference and counter electrode, whereas the cathode is used as the working electrode. 

RDF and RRDE techniques have been widely used for studying the kinetics of the ORR [1-10] and HOR [11-17] in PEM fuel cells. Particularly in ex situ evaluations of catalysts and catalyst layers, the conventional half-cell is used to measure the electrochemical Pt surface area (EPSA), ORR mass activity, catalyst stability, as well as non-noble metal catalyst activity and stability, as described in later sections of this chapter. 

Table 23.5 also lists the Pt surface area calculated from TEM and from EPSA measurement [37]. The Pt surface area of the fresh MEA catalyst layer is also smaller than that of the pristine Pt/C powder. The geometric surface areas of Pt particles calculated from TEM images are larger than the electrochemical active area (ECA). This discrepancy may in part be due to electrochemical inactivity for those Pt particles covered by the ionomer (see Figure 23.22(b)) or embedded in the carbon support. 

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