Hybrid Nafion Membranes of Ionic Hydrogen-Bonded Organic Framework Materials for Proton Conduction and PEMFC Applications

As
the high-power density and environmentally friendly energy resources,
proton exchange membrane fuel cells (PEMFCs) have a promising future
in portable power generation. Herein, the hybrid Nafion membranes
of ionic hydrogen-bonded organic frameworks (iHOFs) for PEMFC applications
are demonstrated. By adjusting the position of sulfonic groups on
naphthalene disulfonic acid compounds, four iHOFs with different types
of hydrogen bonds were synthesized successfully based on 1,1′-diamino-4,4′-bipyridylium
and naphthalene disulfonic acid. The formation of hydrogen bond interactions
between amino and sulfonate groups provides a rich hydrogen bond network,
which makes such iHOFs have high conductivity, and the maximum value
is 2.76 × 10–3 S·cm–1 at 100 °C and 98% RH. Besides, composite membrane materials
were obtained by mixing Nafion and iHOFs, and the maximum proton conductivity
values can achieve 1.13 × 10–2 S·cm–1 for 6%-iHOF-3/Nafion and 2.87 ×
10–3 S·cm–1 for 6%-iHOF-4/Nafion membranes at 100 °C under 98% RH. Through the H2/O2 fuel cell performance test by using iHOF/Nafion as
the solid electrolyte, the maximum power and current density values
of hybrid membranes are 0.36 W·cm–2 and 1.10
A·cm–2 for 6%-iHOF-3/Nafion and
0.42 W·cm–2 and 1.20 A·cm–2 for 6%-iHOF-4/Nafion at 80 °C and 100% RH. This
work provides a practicable approach for establishing high-performance
proton exchange hybrid membranes by doping high proton-conducting
iHOFs into the Nafion matrix.