Tuning clathrate hydrates for hydrogen storage

Clathrate hydrates, in which an ice lattice plays host to molecules of hydrogen gas, are leading candidates for hydrogen storage devices in fuel cells. Some structure II hydrates, with two different sizes of molecular cage, have already achieved good hydrogen storage performance. However, the harsh conditions required for their synthesis and performance make actual applications of the material rather unrealistic. The practical feasibility of these materials for hydrogen storage is now brought closer with the development of structure II gas hydrates stabilized by the inclusion of a water-soluble guest, tetrahydrofuran (THF). The presence of THF enables both the large and small cages of the clathrate to contain hydrogen, achieving an uptake of 4 wt % hydrogen at reasonable pressure conditions, moving these systems still closer to the accepted target for some fuel cell applications.