Storage of hydrogen as HF(H2)n clusters: A theoretical study

The HF(H2)naggregates, the product of intermolecular interactions between H2 and HF molecules, were studied theoretically as hydrogen storage materials. Calculations were performed using the MP2/aug-cc-pVDZ level of theory to predict the adsorption energy and the change in Gibbs free energy for the systems under study. Our results indicate that up to eight H2 molecules can associate with HF, forming HF(H2)8 complexes. Due to the small activation energies for H2 desorption from HF(H2)n species, a large number of hydrogen molecules can be desorbed at low temperatures. The unscaled vibrational stretching frequencies show redshift for H2 and HF bonds. The Natural Bond Orbital calculations were used to analyze the interaction between HF and H2 molecules. Moreover, the cooperativity in HF(H2)nadducts was predicted as a result of the stabilities of clusters. Finally, electronic features of the HF(H2)nadducts were investigated using the density of states calculations.