Developing new materials for the fabrication of proton exchange membranes (PEMs) for fuel cells is of great significance. Herein, a series of highly crystalline, porous, and stable new covalent organic frameworks (COFs) have been developed by a stepwise synthesis strategy. The synthesized COFs exhibit high hydrophilicity and excellent stability in strong acid or base (e.g., 12 m NaOH or HCl) and boiling water. These features make them ideal platforms for proton conduction applications. Upon loading with H3 PO4 , the COFs (H3 PO4 @COFs) realize an ultrahigh proton conductivity of 1.13×10-1 S cm-1 , the highest among all COF materials, and maintain high proton conductivity across a wide relative humidity (40-100 %) and temperature range (20-80 °C). Furthermore, membrane electrode assemblies were fabricated using H3 PO4 @COFs as the solid electrolyte membrane for proton exchange resulting in a maximum power density of 81 mW cm-2 and a maximum current density of 456 mA cm-2 , which exceeds all previously reported COF materials.
Keywords: covalent organic frameworks; fuel cells; membranes; multiple-bond linkages; proton conduction.
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