Multiple-length scale investigation of Pt/C degradation by identical-location transmission electron microscopy

Abstract

Pt-based electrocatalysts on the cathode side of proton exchange membrane fuel cells (PEMFCs) generally undergo severe degradation, which contributes to the short life span of PEMFCs. Thus, it is crucial to understand the structural degradation of Pt-based electrocatalysts. Here, various degradation mechanisms of individual Pt nanoparticles supported on Vulcan carbon during load-cycle accelerated stress tests were investigated and quantified by identical-location transmission electron microscopy (IL-TEM). The atomic-scale IL-STEM imaging revealed the formation of Pt single atoms on the carbon support, which resulted from the dissolution of nanoparticles, and the following pathway change in the oxygen reduction reaction (ORR) was analyzed by rotating ring-disk electrode tests. Our study provides new insight for understanding the relationship between the decline in the ORR activity and the formation of Pt atomic species resulting from the electrochemical degradation of Pt/C.