High-density sulfonic acid-grafted covalent organic frameworks with efficient anhydrous proton conduction

A high-density sulfonic acid-grafted COF was designed and synthesised with a high intrinsic proton conductivity (1.52 × 10 −4 S cm −1 at 120 °C). Further incorporation of a protic ionic liquid into the COF highly improved its proton conductivity to 2.21 × 10 −3 S cm −1 at 120 °C.