Impact of Pt spatial distribution on the relative humidity tolerance of Pt/C catalysts for fuel cell applications

The distribution of platinum group metal (PGM) nanoparticle catalysts throughout the porous structure of the carbon support has been widely reported to have a significant impact on the performance of the catalyst. For catalysts having Pt primarily on the outer surface of the carbon, low mass activity but excellent performance at high current densities is often observed. Conversely, when Pt is deposited within the pores of the carbon, high mass activity but poor performance at high current density is observed. This relationship has been well studied, and the mechanism has been clearly elucidated. A key method in the literature to study Pt distribution has been the 'Pt accessibility' tests, which are based on monitoring roughness factor (cm(2)Pt/cm(2 )membrane electrode assembly (MEA)) vs. relative humidity (RH). While these tests have now been correlated with performance, most of the polarization testing during these studies is performed under one single RH condition. In this work, the relationship between Pt spatial distribution and RH tolerance is probed to gain further insight into how the materials-level properties of the catalyst impact MEA-level characteristics. This work provides an additional design tool that can be used by MEA designers when selecting catalysts for their specific application.

Automated summary

The distribution of platinum group metal (PGM) nanoparticle catalysts in the carbon support significantly affects the catalyst's performance. The placement of Pt either on the outer surface or within the pores of the carbon results in different activity and performance at high current densities. To gain further insight into the catalyst's properties, a relationship between Pt distribution and relative humidity (RH) tolerance is explored. This work provides valuable information for MEA designers in selecting catalysts for specific applications.