The durability test was done by using the following condition:
air saturated 0.1M HClO4 , 500mV/s , 1-1.5V V RHE.
Catalyst Preparation:
1mL ethanol, 0.01 catalyst, Nafion ionomer(5wt%) 2 μL.
before durability test, I did cv and ORR. After ORR, I did ADT test.
But, during durability test, I didn't found any significant change.
I made also Pt/PCNF, but there is no change as we see in the paper.
Besides, during CV, at lower scan rate such as 20mV/s Pt-H ads/Pt-H-desorp peak were lower than the peak for pt-oxide formation. But at higher scan rate such as 50mV /s , the peak was okay.
Is anyone have that experience? or do you have any suggestion for that?
Thanks in advance
There is no ideal reason why a cell should degrade from many cycles. Cells do degrade from side reactions accumulating a byproduct that doesn't decompose completely in recharging. Much research has been done to find compositions that are self protecting. That is some property of the starting materials allow them to avoid byproducts and to decompose the ones that normally occur. Usually the researcher has done this deliberately and knows which conditions are being prevented.
That looks like you approximated the newer protocol DOE AST, but most of those are performed in a full cell. By keeping the system flooded, you're protecting your catalyst layer to an extent. Also, with a low wt% PFSA (5% vs. 30%) + absence of a membrane, you're substantially reducing exposure to superacids from the membrane/ionomer, which definitely plays a role in Pt corrosion, and likely in support corrosion as well.
That said, you referenced a paper that did see degradation - was it in an identical system and scan rates? Either way, it would be an interesting comparison to perform the old AST, 400 h 1.2 V hold. The new ASTs were made with full cells in mind, so it may well be that the translation to RDE analysis simply failed to translate similarly.
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