Effects of substituents on the H2 storage properties of COF-320

•Functionalize the structure with different substituent groups.•Explore the effects of different substituents on the H2 storage properties.•Analyze adsorption isotherms and isosteric heat of H2 on COF-320–X frameworks.

COF-320 is a new 3D framework material with remarkable thermal and chemical stability. In order to improve the H2 storage properties, COF-320–X frameworks were developed by replacing H atoms on the benzene ring of COF-320 to functionalize the structure with different substituent groups, including –OH, –Cl, –NO2, –NH2, –CH3, and –CN. We studied the adsorption properties of H2 on COF-320–X by the GCMC method, mainly analyzed the adsorption isotherms and isosteric heat at 298 K and 77 K. The results showed that all these substituents can improve the H2 storage properties of COF-320, and –NH2 is the best one among these groups. The H2 storage capacity can be increased by 27.6% and 35.2% respectively at 298 K and 77 K.