Arylsulfonate Ionic Hydrogen-Bonded Organic Frameworks Enable Highly Stable and Superprotonic Conductivity for Enhancing Direct Methanol Fuel Cells

Developing proton-conducting materials
with superior
proton conductivity
and excellent stability plays an indispensable role in the advancement
of direct methanol fuel cells (DMFCs). In this work, we successfully
synthesized an ionic hydrogen-bonded organic framework (iHOF-13) with 3D hydrogen-bonding network structures. The inherent abundance
of hydrogen bonding networks in HOFs enables them to exhibit superprotonic
conductivity. Specifically, iHOF-13 demonstrates a proton
conductivity of 1.3 × 10–1 S cm–1 at 98% relative humidity and 100 °C. The iHOF is enriched with
proton transport sites, and its doping into the Nafion matrix exhibits
extremely high proton conductivity (10–1 S cm–1) and low methanol permeability. The maximum power
density of the 7.5%-iHOF-13/Nafion composite membrane
can reach 104.7 mW cm–2 in DMFCs, which is 2.1 times
higher than that of recast Nafion. The incorporation of high-performance
iHOF facilitates the enhancement of the proton transport pathway while
effectively inhibiting methanol crossover, thus expanding its potential
application in fuel cells.