Electrospun imidazolium functionalized multiwalled carbon nanotube/ polysulfone inorganic-organic nanofibers for reinforced anion exchange membranes

Novel electrospun inorganic-organic nanofiber reinforced anion exchange membranes were developed by incorporating imidazolium functionalized multiwalled carbon nano tubes (FMWCNTs) into imidazolium functionalized polysulfone nanofibers via co-electrospinning. Under a high-voltage electrostatic field, FMWCNT inorganic nanofibers were able to align along the axis of the electrospun nanofibers, thereby solving the problem of easy agglomeration of FMWCNTs in cast-composite anion exchange membrane, synergistic with the polymer nanofibers to reinforce the membranes. Small angle x-ray suggests that ion clusters are more likely to aggregate in a co-electrospun composite membrane, indicating continuous and lower-energy-barrier pathways for hydroxide transport. As a result, composite electrospun membranes exhibit higher OH- conductivity and better single fuel cell performance. With an additive amount of 0.4 wt.%, hydroxide conductivity reaches a maximum value of 67.5 mScm(-1) (30 degrees C). However, the maximum power density (102.5 mW cm(-2)) is much higher than that of the electrospun (2.1 times) and cast (3.3 times) membranes without FMWCNTs. Fibration of polymer and alignment of multiwalled carbon nanotube nanofibers also greatly enhance the membrane strength. For fully hydrated membranes, tensile stress dramatically increases from 5.6 MPa for a cast membrane without FMWCNTs to 24.4 MPa for an electrospun membrane with 0.4 wt.% FMWCNTs addition. The strategy for co-electrospinning of imidazolium functionalized multiwalled carbon nanotubes/polysulfone presented in this work provides a way to enhance the organic-inorganic interface compatibility, and improve ionic conductivity and mechanical strength of anion exchange membrane simultaneously. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.