Carbon nanocomposites self‐assembly UiO‐66‐doped chitosan proton exchange membrane with enhanced proton conductivity

Abstract

One-dimensional (1D) sodium ligninsulfonate functionalized carbon nanotubes (SCNT), two-dimensional (2D) graphene oxide (GO), and three-dimensional (3D) zirconium-based metal-organic frameworks (UiO-66) are self-assembled as filler materials for proton-exchange membranes (PEMs) because of their potential for extending proton transport pathways. Herein, UiO-66-SCNT and UiO-66-SCNT@GO were prepared by a facile solvothermal synthesis and then the nanohybrid chitosan (CS) PEMs were fabricated via solution casting. The hybrid PEMs with higher ion exchange capacity than the pure CS membrane displayed higher proton conductivity and selectivity. The proton conductivity of nanohybrid membrane doped with 7 wt% UiO-66-SCNT@GO (CS/U-S@GO-7) was enhanced to 64 mS cm−1 at 70°C. Simultaneously, the selectivity was reached 19.4 × 104 S s cm−3 and was much higher than the pristine CS membrane (0.13 × 103 S s cm−3). Moreover, the mechanical properties of all composite membranes were significantly enhanced compared with that of the pure CS membrane. The results showed that our research provided a valuable strategy for designing high-performance CS-based PEMs in direct methanol fuel cell (DMFC). Highlights A simple and facile solvothermal synthesis was used to prepare UiO-66-SCNT@GO. UiO-66-SCNT@GO was introduced into chitosan (CS) matrix to optimize proton transport channels. CS-based hybrid membranes exhibit high proton conductivity and selectivity. CS-based hybrid membranes show low methanol permeability.