The binder of the Pt catalyst used in the cathode of the microbial fuel cell is this.
Perfluorinated resin solution containing Nafion™ 1100W
5 wt. % in lower aliphatic alcohols and water, contains 15-20% water
However, it was discontinued in Sigma Aldrich, and it is said that it will not be available in the future. If you have an alternative, please share it.