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.