The Monte Carlo simulation study on H₂ adsorption in two-dimensional covalent-organic frameworks

The physisorption properties of H₂ in two dimensional covalent organic frameworks (2D COFs) with different structures and compositions were studied using Grand Canonical Monte Carlo method. The simulated results show that, (1) among all of 2D COFs studied, the ILCOF-1 has the best performance for hydrogen storage owing to its highest surface area. Compared with other 2D COFs studied by other scientific groups, ILCOF-1 is the one of 2D COFs with the highest H₂ uptakes. The adsorption amounts of other five 2D COFs are lower than those of COF-5, -8, -10, TP-COF, and are almost the same with those of COF-1, -6, Pc-PBBA COF. (2) Compared to 3D COFs, the adsorption capacities of 2D COFs studied in this paper are lower than those of COF-105 and COF-108. Except for ILCOF-1, the other five 2D COFs have lower adsorption capacities than COF-102 and COF-103. The effects of pore size, surface area and isosteric heats of hydrogen on adsorption amounts are considered, which indicate that all of these three factors are important for determining the H₂ uptakes. Finally, we put forward some constructive suggestions about how to improve the adsorption capacity of COFs according to the results of our GCMC simulation. This may be useful for further investigation. (authors)