Surface-modified Nafion® membrane by casting proton-conducting polyelectrolyte complexes for direct methanol fuel cells

Surface-modified Nafion® membrane was prepared by casting proton-conducting polyelectrolyte complexes on the surface of Nafion®. The casting layer is homogeneous and its thickness is about 900 nm. The proton conductivity of modified Nafion® is slightly lower than that of plain Nafion®; however, its methanol permeability is 41% lower than that of plain Nafion®. The single cells with modified Nafion® exhibit higher open circuit voltage (OCV = 0.73 V) and maximal power density (Pmax = 58 mW cm−2) than the single cells with plain Nafion® (OCV = 0.67 V, Pmax = 49 mW cm−2). It is a simple, efficient, cost-effective approach to modifying Nafion® by casting proton-conducting materials on the surface of Nafion®.