Elucidating the degradation mechanism of the cathode catalyst of PEFCs by a combination of electrochemical methods and X-ray fluorescence spectroscopy

摘要: In this study, we report a methodology which enables the determination of degradation mechanisms responsible for catalyst deterioration under different accelerated stress protocols (ASPs) by combining measurements electrochemical surface area (ECSA) and Pt content (by X-ray fluorescence). The validation method was assessed on high unsupported nanoparticles (Pt-NPs), supported TaC (Pt/TaC) Vulcan carbon (Pt/Vulcan). load cycle protocol, Pt-NPs Pt/Vulcan follows associative processes (e.g. agglomeration) in first 2000 cycles, however, successive cycles goes through dissociative such as dissolution, is evident from similar decay ECSA content. contrast, mechanism dispersed occurs continuously dissolution or particle detachment), with rates both ECSA. start-up/shut-down follow Ostwald ripening) 4000 after continues processes. On other hand, always govern Pt/TaC protocol conditions. Finally, that exhibit highest catalytic activity long term durability three nanoparticle systems tested. This makes potentially valuable system application polymer electrolyte fuel cell cathodes.