Prism patterned TiO2 layers/Nafion® composite membrane for elevated temperature/low relative humidity fuel cell operation

A simple and facile way of modifying commercial membranes for effective fuel cell operation under elevated temperature/low relative humidity conditions has been developed. Instead of using the conventional casting and evaporation method involving the mixed Nafion (R) ionomer and inorganic fillers, a TiO2/Nafion (R) composite membrane was fabricated by transferring uniformly constructed porous TiO2 layers from a Si wafer to the Nafion (R) membrane via spin-coating, followed by a thermal imprinting process. From the process, filler agglomeration was prevented during the solvent evaporation, which secured water retention effect of the hygroscopic TiO2 layers. Furthermore, the prepared TiO2/Nafion (R) composite membrane was subjected to an additional prism patterning process to provide more proton pathways by enlarging the interfacial surface area between the composite membrane and the catalyst layer, and offset the reduced proton conductivity due to insertion of the inorganic fillers. The modified membrane exhibited highly improved performance compared to the pristine Nafion (R) 211 membrane under elevated temperature/low humidity conditions. (C) 2020 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.