Enhanced stability and ultrahigh proton conductivity of hydrogen-bonded organic frameworks

Abstract

The low stability of hydrogen bonded organic frameworks (HOFs) greatly limits their practical application. Herein, we synthesized a sulfonate-containing HOF and further improved its stability by crosslinking its crystal particles based on an in situ reaction of ammonia on its surface. The obtained HOF-based composite HDSD-1@Tp can maintain stability in common organic solvents, boiling water and acid solutions (3 M), the mixed solution of DMF and water (1 : 1) and basic solutions up to pH = 12. The pore structure formed by the organic linkages between HDSD-1 crystal particles not only enhances the stability of HDSD-1, but also is conducive to the storage of guest water molecules. When NH₄⁺ that can serve as a proton source and improve the hydrophilicity of the material is introduced into HDSD-1@Tp, the obtained HDSD-1@Tp-NH₃ exhibits an ultrahigh proton conductivity of 3.8 × 10⁻¹ S cm⁻¹ at 80 °C 98% RH. In this work a new strategy for the synthesis of novel HOF-based proton conducting materials with excellent stability and high proton conductivity has been developed.