Selective Distributing Features of PFSA Ionomer on Pt/C in PEMFC

Unconventional ORR polarization exacerbates the performance degradation of the PEMFC, which is directly related to the interfacial features of Pt/Nafion. Therefore, the distribution of Nafion on the Pt surface is an important issue for the in-depth analysis of Nafion poisoning and is likely to be a breakthrough to completely solve it. In this work, we first visualized the selective distribution of Nafion on Pt surface by TEM-EDS. Simultaneously, Nafion-coated CLs with different areal loadings by thinning and diluting processes underwent delicate electrochemical measurements, which demonstrates that the coverage of sulfonate on Pt is proportional to the Pt loading, further proving the preferential distribution of Nafion on Pt compared with carbon by quantitative data analysis. As such, this groundbreaking work with an innovative approach, including qualitative visual observation and quantitative electrochemical calculation, provides a new horizon for the understanding of Nafion poisoning on Pt-based oxygen reduction catalysts and is meaningful to the local structure design of anti-Nafion-poisoning catalysts.