Green Synthesis of Olefin-linked Covalent Organic Frameworks for Hydrogen Fuel Cell Applications

Green synthesis of crystalline porous materials for energy-related applications is of great significance but very challenging. Here, we create a green strategy to fabricate a highly crystalline olefin-linked pyrazine-based covalent organic framework (COF) with high robustness and porosity under solvent-free conditions. The abundant nitrogen sites, high hydrophilicity, and well-defined one-dimensional nanochannels make the resulting COF an ideal platform to confine and stabilize the H₃PO₄ network in the pores through hydrogen-bonding interactions. The resulting material exhibits low activation energy (E_a) of 0.06 eV, and ultrahigh proton conductivity across a wide relative humidity (10–90 %) and temperature range (25–80 °C). A realistic proton exchange membrane fuel cell using the olefin-linked COF as the solid electrolyte achieve a maximum power of 135 mW cm⁻² and a current density of 676 mA cm⁻², which exceeds all reported COF materials.