Channel-Assisted Hydrogen-Bonded Organic Frameworks for Enhanced Proton Conduction Against Weak Humidity

Hydrogen-bonded organic frameworks (HOFs) are a type of solid electrolyte that show potential for use in proton exchange membrane fuel cells. The hydrogen bonding network within their structure has sparked interest in their application. Introducing a proton source into HOFs can form a multiple hydrogen bonding network, creating effective transport channels that enhance proton conductivity across a broad humidity range. Herein, we aim to create a dense multidimensional hydrogen bonding network by encapsulating glycinamide hydrochloride (GAH). Modifying the pores results in an unusual breathing effect, allowing for increased binding of water molecules. This alteration in structure leads to a shift in the proton conduction properties from their original state. The synthesized GAH@PFC-33 exhibits superior proton conductivity compared to PFC-33 across a range of relative humidities from 0% to 98%. At 98% relative humidity and 90 °C, GAH@PFC-33 achieves the highest proton conductivity rate of 7.2 × 10–3 S cm–1, surpassing the performance of most reported HOF materials. The presence of unbonded carboxyl groups on the HOF surface and the groups on the modified CBA-SPVA enabled the formation of composite membranes through hydrogen bonding self-assembly. This led to the production of self-assembled HOF membranes with improved proton conductivity, making them promising candidates for fuel cell applications. This study opens up possibilities for utilizing HOF materials in proton conduction.