Nafion/graphene oxide composite membranes for low humidifying polymer electrolyte membrane fuel cell

Graphene oxide was prepared from graphite using Hummerʹs method. Pt nanoparticles with 1.8 nm in average size are successfully obtained via in-situ Pt nanoparticles deposition onto graphene oxide (GO) using a microwave method, finally resulting in Pt-graphene (Pt-G). Water uptake of GO is increased with GO content in a Nafion/GO composite membrane due to the hydrophilic GO while that of Nafion/Pt-G composite membrane is much lower than that of Nafion/GO composite membrane. The MEAs fabricated with the Nafion/GO composite membrane show significant enhancement in cell performance: that is, 0.802 A, 1.27 A, 0.827 A at 0.6 V under 100% relative humidity (RH) for 0.5 wt%, 3.0 wt% and 4.5 wt% of GO content in the composite membrane, respectively, compared to 0.435 A for casting Nafion membrane. The Nafion/Pt-G composite membrane, however, does not show sufficient enhancement under various RHs. It is attributed to poor water retention ability of hydrophobic graphene and electron loss due to the formation of electrical network by too much Pt within the membrane. Constant open circuit voltage (OCV) down to low RH indicates that GO and graphene could be prospective as filler in low humidifying polymer electrolyte fuel cell.