Dear Vani Rajagopal,

The optimization of MEA could takes six months. The best solvent is water and the additive is nafion and IPA. You should vary the concentration of these three then you will get a consistent ink for the coating. No papers were clearly mentioned the ratio, but they just mentioned "water, IPA and nafion with an appropriate percentage". 

Hi Vani,

Follow this paper, it's great: http://doi.org/10.1021/acs.analchem.6b03005

The ratio many papers have optimized is 30 wt% Nafion, 70 wt% Pt/C catalyst. 20 wt% Pt is a little low, but there's reference data out there. Don't use glycerol - 1:1 methanol:water is fine. Also please don't hot press - it doesn't help and introduces inconsistencies, as thoroughly shown in the above paper. 

For deposition, the best method is ultrasonic spray-coating of your membrane fixed onto a heated substrate (e.g. 50-80 °C) if you can, or hand-spraying if not. Inkjet can get close to hand-spraying and helps consistency but then solvent effects become much more of an issue.

Best regards,

Ben

Thank you Mr. Natarajan and Mr. Benjamin for your valuable feedback. Yes in papers i could not find the exact ratio. We tried with glycerol, IPA and TBAOH. And we did normal painting as the spray coating facility wasn't available. Paintability was good but transfer was bad in almost all the cases. 

Mr.Benjamin, i thought in spray coating the quantity of ink required was more. Could you please correct me if i am wrong?

Hi again Vani,

If you hand spray, absolutely yes more ink is required, but it is an industrially viable technique because overspray is very minimal with automated spray-coaters and large samples. I've seen at least four papers that optimized Nafion content for different Pt/C-type catalysts and all landed at 30 wt% (if I recall one said 30 wt% cathode, 25 wt% in the anode, but anode composition is very insensitive until you go to low catalyst loadings) -- there's lots of parametric optimization data out there, especially from the 90's.

Benjamin Britton

Hi

Thanks for your replies

do you have a reference saying that anode is insensitive to ionomer content at high loading ?

Regards