Orderly sandwich-shaped graphene oxide/Nafion composite membranes for direct methanol fuel cells

A novel type of graphene oxide (GO)/INafion composite membrane is fabricated and used as a proton exchange membrane for direct methanol fuel cells (DMFCs) in this article. The membranes are prepared by depositing GO nanosheets on the surface of recast Nafion (R) 117 via a layer-by-layer (LbL) procedure using 1, 4-phenyldiamine hydrochloride (PDHC) as the cross-linker. This approach prevents the GO nanosheets from dissolving in water and imparts the composite membranes a good stability. The methanol permeability of the composite membranes is lower than that of recast Nafion (R) 117 measured under the same conditions. The composite membrane with 80-layered GO nanosheets exhibits a value of 6.7 x 10(-8) CM2 s (-1) at 30 degrees C, which is two orders of magnitude lower than that of recast Nafion (R) 117. In addition, the relative selectivity of the composite membranes is 5 times higher than that of recast Nafion (R) 117. The endurance time of the composite membranes in Fenton's reagent is 10 times longer than that of Nafion. Single cell evaluation using the composite membrane with 50-layered GO showed an open circuit voltage (OCV) of 0.67 V. A maximum power density of 64.38 mW cm(-2) at a current density of 200 mA cm(-2) can be achieved at 60 degrees C. (C) 2015 Elsevier B.V. All rights reserved