Covalent organic frameworks (COFs), as emerging crystalline porous materials featuring abundant pores, well-defined aligned channels, atomically tunable structures, and easily functionalized backbones, have attracted considerable attention. These characteristics enable them to provide highly efficient mass transfer pathways and precisely engineered active sites and act as hosts for functional guests, thereby enhancing dispersibility, uniformity, and stability while also creating a modifiable microenvironment, which highlights the great potential of COFs in electrochemistry-related applications. In this review, we present recent advances in the application of COFs in proton exchange membrane fuel cells, including as oxygen reduction reaction catalysts, proton exchange membranes, and ionomers. We highlight the roles played by COFs in these applications, focusing on their structural design and modulation, facilitation of electrochemical processes, and enhanced mass transport pathways. Finally, key challenges and future directions for the development of COF-based materials in proton exchange membrane fuel cells are discussed.

Porous organic polymers hold great promise for molecular sieving membrane separation. Although the inclusion of functional ionic liquid (IL) in the pores offers a facile way to manipulate their separation properties, the IL leaching during the separation process is difficult to avoid. Herein, we report a strategy to in-situ encapsulate ILs into the micropores of the conjugated microporous polymer membrane via a 6-min electropolymerization and further seal the aperture of the pores to prevent ILs leaching by solvent-assisted micropore tightening (SAMT). Upon screening the binding energy between different ILs and gas molecules, two ILs were selected to be incorporated into the membrane for CO₂/CH₄ and O₂/N₂ gas separations. The resultant separation performances surpass the 2008 Robeson upper bound. Notably, the ILs can be locked in the micropores by a facile high surface tension solvent treatment process to improve their separation stability, as evidenced by a 7-day continuous test. This simple and controllable process not only enables efficient and steady separation performance but also provides an effective strategy for confining and sealing functional guest molecules in the porous solids for various applications.