Three-Dimensional Covalent Organic Framework for Efficient Hydrogen Storage through Polarization-Wall Engineering

Covalent organic frameworks (COFs), characterized by high surface areas and tunable pore structures/environments, are regarded as a promising alternative to physisorption H₂ storage materials. However, their interaction with hydrogen is often too weak, necessitating the exploration of strategies to enhance sorption heat. Herein, we strengthened the adsorption induction of COF on H₂ through a polarized wall engineering. The fluorine groups on the pore wall of three-dimensional COFs polarize their surrounding regions, resulting in high sorption heat sites. Due to the enhanced H₂ sorption heat, the total H₂ uptake of 3D-F-COF is up to to 5.96 wt % at 77 K and 90 bar. Moreover, the H₂ adsorption enhancement effect of the polar group does not involve chemisorption, and the material exhibits excellent cycling stability. These results reveal that modulating the H₂ sorption heat by incorporating polar groups is a promising strategy for achieving efficient H₂ storage in porous materials.