While it is clear that the degradation rate of both metals is highly dependent on the hold time at UPL, before a more comprehensive explanation of this conclusion, let us focus now on the varying potential window. In accordance with the assumptions from the results obtained using the HT-DE methodology (Figure ), the signals for both Pt and Co dissolution decrease substantially with the narrowing potential window from 0.6-0.95 VRHE (Figure ,c,e) to 0.7-0.85 VRHE (Figure ), regardless of the applied hold time at each potential. This is also by the previous findings, but what is specific here is that both LPL and UPL are nevertheless limited to a realistic operational voltage while positively affecting the stability of both metals. related to the oxide place-exchange is more damaging than anodic transient dissolution. Nevertheless, using the 1 st protocol, we are unable to deconvolute between both contributions precisely. To improve the resolution between both the anodic as well as cathodic metal dissolution peaks, the UPL hold time has been extended to 1 min (2 nd protocolsee Therefore, the oxide-place exchange mechanism plays an important role not only in a wide potential window, but also in a very narrow operational potential window such as used here (0.6-0.95 VRHE and 0.7-0.85 VRHE). (ii) Narrowing the voltage window to only 0.7-0.85 V greatly inhibits both the anodic as well as cathodic dissolution of both Pt and consequently Co and thus, could significantly prolong the lifetime of Pt-alloy cathodes in PEMFCs using already existing state-of-the-art Pt-alloy catalysts.