Highly ordered graphene oxide paper laminated with a Nafion membrane for direct methanol fuel cells

•A GO-laminated Nafion membrane for DMFC is originally proposed.•The parallel orientation of the GO paper can effectively block methanol crossover.•The novel membrane shows its superiority in DMFC at higher methanol feed concentrations.

This study presents graphene oxide (GO)-laminated Nafion 115 as a proton exchange membrane for a direct methanol fuel cell (DMFC). Compared to a GO-dispersed polymer composite membrane, a GO-laminated proton-conducting membrane is advantageous for DMFC operating at higher methanol feed concentrations. The novel laminate membrane consists of highly ordered GO paper with parallel orientation prepared by using a vacuum filtration method. This dual-layer membrane is fabricated by laminating the Nafion 115 membrane with a highly orientated GO paper through transfer printing followed by hot-pressing. Scanning electron microcopy (SEM) shows that the GO paper measuring approximately 1.0 μm thick (i.e., corresponding to 1.5 wt%) adhered well to the base membrane. The methanol permeability of the GO-laminated membrane is approximately 70% lower than that of Nafion 115 at an expense of a 22% decrease in proton conductivity. The proposed membrane has a 40% higher selectivity (i.e. ratio of proton conductivity to methanol permeability) than Nafion 115. The GO-laminated Nafion membrane is far superior to the pristine Nafion membrane in DMFC performance when operating at an 8 M methanol feed concentration.