Improving hydrogen storage properties of covalent organic frameworks by substitutional doping

We proposed a possible way of promoting the binding of H2 molecules on covalent organic frameworks crystals via substituting the bridge C2O2B rings with different metal-participated rings, which can naturally avoid the clustering of metal atoms. First-principles calculations on both crystalline phase and molecular fragments show that the H2 binding energy can be enhanced by a factor of four with regard to the undoped crystal, i.e. reaching about 10 kJ/mol. Grand canonical Monte Carlo simulations further confirm that such substitutional doping would improve the room temperature hydrogen storage capacity by a factor of two to three.