Hydrogen-bonded organic framework membrane with efficient proton conduction

Hydrogen-bonded organic frameworks (HOFs) with continuous hydrogen bond networks, programmable pore structure and functional sites, are promising next-generation functional membrane materials. Here, we demonstrate the fabrication of a free-standing HOF membrane for the first time, and explore the proton conduction performance. Concretely, HOF membrane was prepared by assembling HOF precursors into nanosheets, followed by vacuum filtration and annealing treatment. We confirm that the annealing treatment exerts significant influence on membrane topology, which allows the construction of efficient vertical conduction pathways. The vertical conductivity of HOF membrane reaches 59.8 mS cm−1 at 90 °C and 100% relative humidity (RH), with low conduction anisotropy of 4.4, which are superior to most organic framework membranes. The maximum current density and power density of assemble hydrogen fuel cell under 60 °C and 40% RH reach 279 mA cm−2 and 79 mW cm−2, respectively. This study may provide some guidance on HOF membrane fabrication.