But the main challenge is the manufacturing of the MEA (either by CCM und gas diffusion electrodes) with the catalyst materials and achieving a good reproducibility from one MEA to the next one. You need to become very familiar with the preparation of the MEAs and electrodes and you should try to achieve small deviations between each new MEA sample.
Otherwise you simply start comparing production processes only which might have nothing to do with performance improvement you intend, for example by a new catalyst material. In other words, a good and highly active catalyst and a badly manufactured electrode or MEA might give you a very low or even no performance in FC tests. And how do you find out what the real reason is?
It depends on which fuel cell you want to use it as a catalyst. For example, in the case of methanol fuel cell, If your intention is just to evaluate the material as a potential catalyst, then you can disperse a drop of the catalyst with Nafion on the CPE, dry it and test it in the usual away in a cell with a suitable electrolyte containing methanol. Obviously, the fuel cell electrode fabrication using the material is a different technique and a more complicated process.