Initial driving force for proton transfer in Nafion

We explore the initial driving force for proton transfer in Nafion using ab initio density functional calculations. We confirm that the direct and indirect proton transfer mechanisms are possible based on the previously suggested mechanisms. The initial proton transfer involves a water molecule (H2O) and a subsequent hydronium ion (H3O+) via the hydrogen bonding between the aqueous media and the -SO3- groups of the Nafion side chains to reorganize and energetically stabilize the side chains. The proton transfer is favorably assisted via the H2O molecule between the two -SO3- groups involving the internal conversion between covalent and hydrogen O-H bonds.