Nafion® and nanocellulose: A partnership for greener polymer electrolyte membranes

• Novel nanostructured composite of Nafion® and bacterial cellulose is fabricated.
• Nanocomposite membrane exhibits good thermal, mechanical and viscoelastic properties.
• Membrane with high proton conductivity is effectively used in a lab-scale fuel cell.
• These composite membranes demonstrate potential as green proton separator materials.

This paper reports the characterization of a Nafion®/bacterial cellulose (BC) nanocomposite prepared by impregnation of a nanofibrillar BC membrane with Nafion®. Such nanocomposite membrane is obtained crack-free and with thickness close to 100 μm. Dynamic mechanical analysis reveals a storage modulus more than 1 order of magnitude higher than for pure Nafion®, with BC effectively limiting the viscous flow of the nanocomposite up to 125 °C. The in-plane protonic conductivity is 0.14 S cm−1 at 94 °C and 98% relative humidity, which is lower than for pure Nafion®, but in line with the lower concentration of acid groups of the composite (0.60 vs. 0.92 mmol [H+] g−1 for Nafion®). The application of the Nafion®/BC membrane in an air/hydrogen fuel cell is demonstrated.

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