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.