Alkaline anion exchange membranes based on KOH-treated multilayer graphene oxide

Abstract A novel class of alkaline anion exchange membrane (AAEM) is presented, in the form of KOH-modified multilayer graphene oxide paper (GO KOH ). Such membranes can be easily fabricated at large scale with varying thickness using conventional filtration techniques, and have high tensile strength (24.5 MPa). However, a large degree of swelling is observed. SEM investigations show that the morphology of GO changes after KOH-treatment, whilst XPS measurements and XRD analysis confirm successful chemical modification. The hydrogen gas permeability is several orders of magnitude lower than conventional polymer-based ionomer membranes. The maximum anion conductivity is 6.1 mS/cm at 70 °C, and the dominant charge carrier is confirmed to be OH − by utilization of anion and proton-conducting blocking layers. The ion exchange capacity is 6.1 mmol/g, measured by titration. A water-mediated reverse Grotthuss-like mechanism is proposed as the main diffusion mode of OH − ions. Finally, a prototype AAEM fuel cell is fabricated using a GO KOH membrane, confirming the applicability to real systems.