Structure of PFSA polymer

The SO H group is ionically bonded, and so the ends of the side chain - actually an SO ion with ion. This is why such structure is called ionomer. Because of their 

A fuel cell electrode is essentially a thin catalyst layer pressed between the ionomer membrane and porous, electrically conductive substrate. It is the layer where the electrochemical reactions take place. More precisely, the electrochemical reactions take place on the catalyst surface. Because there are three kinds of species that participate in the electrochemical reactions, namely gases, electrons and protons, the reactions can take place on a portion of the catalyst surface where all three species have access. Electrons travel through electrically conductive solids, including the catalyst itself, but it is important that the catalyst particles are somehow electrically connected to the substrate. Protons travel through ionomer therefore the catalyst must be in intimate contact with the ionomer. And finally, the reactant gases travel only through voids therefore the electrode must be porous to allow gases to travel to 

The most common catalyst in PEM fuel cells for both oxygen reduction and hydrogen oxidation reactions is platinum. In the early days - PEMFC development large amounts of Pt catalyst were used (up to 28 mg cm ). In the late 1990s, with the 

To minimize the cell potential losses due to the rate of proton transport and reactant gas permeation in the depth of the electro catalyst layer, this layer should be made reasonably thin. At the same time, the metal active surface area should be maximized, for which the Pt particles should be as small as possible [1]. 

A layer between the catalyst layer and bipolar plates is called a gas diffusion layer, electrode substrate, or diffuser/current collector. Although it does not directly participate in the electrochemical reactions, a gas diffusion layer in PEM fuel cells has several important functions [1]  

---

Figure 1 describes the chemical structure of PFSA polymers, which was widely used as perfluorinated electrolytes for PEFCs. The structure is based on copolymers of tetrafluor-oethylene (TFE) and perfluorovinyl ether monomers with a side chain of sulfonic acid group. While many acid groups have been examined in... 

---