Fluorophilic cobalt phthalocyanine-containing Nafion membrane: High oxygen permeability and proton conductivity in the membrane

A multiply-fluorinated cobalt phthalocyanine (CoFPC) was prepared, which could reversibly interact with oxygen. CoFPC was introduced into the hydrophobic perfluoroethylene-backbone domain of the Nafion membrane. The localization of CoFPC did not reduce the high proton conductivity (10^-2-10^-3 S cm^-1) ascribed to the hydrophilic channel of Nafion. The oxygen permeability through the CoFPC/Nafion membrane was higher than the nitrogen permeability and that of the pristine Nafion membrane, and was significantly enhanced at the lower upstream pressure. The permselectivity of oxygen versus nitrogen increased beyond 20 with the CoFPC content in the membrane. The CoFPC/Nafion membrane was coated on a glassy carbon modified with a Pt/C catalyst. The high electrochemical reduction current of oxygen suggested that the CoFPC/Nafion membrane efficiently supplied oxygen to the Pt/C catalyst.