Enhanced Performance of the Chitosan Proton Exchange Membrane via Anatase Titania Anchored GO and Sodium Ligninsulfonate Constructing Proton Transport Channels

Abstract

Anatase titania anchored graphene oxide (TGO) and sodium ligninsulfonate (SLS) were introduced into the chitosan (CS) proton exchange membrane (PEM) by solution casting to improve its mechanical strength, proton conductivity, and selectivity. Herein, TGO, an association of proton conduction and enhancements, was fabricated by a facile one-step hydrothermal method. As compared to the pristine CS membrane, nanohybrid membranes introduced by graphene oxide (GO), TGO, and SLS showed better thermal stability, mechanical stability, chemical stability, and selectivity due to the strong electrostatic interaction and H-bonding between CS, cross-linking agent, and fillers. The proton conductivity of the nanohybrid membrane doped with 2 wt % TGO and 3 wt % SLS (CS/TGO2/SLS3) was enhanced to 43.85 mS cm–1 at 70 °C. In general, the selectivity of the CS/TGO2/SLS3 sample reached 22.15 × 104 S s cm–3, which was much higher than that of the pristine CS membrane (0.13 × 103 S s cm–3). The introduction of TGO extends the proton transport channels in the membrane, and SLS provides more proton hopping sites. Thus, with improved properties, CS hybrid membranes could be promising as a PEM for direct methanol fuel cells (DMFCs).