Hydrogen Clathrate

A hydrogen clathrate is a clathrate, a cage-like crystal structure built from water molecules, that traps hydrogen molecules inside its lattice, and it has drawn scientific interest chiefly as a possible way to store hydrogen within a future hydrogen economy. It is unusual among clathrates in that more than one hydrogen molecule can occupy a single cage at once, and the highest hydrogen to water ratio achieved so far is six hydrogen molecules to seventeen water molecules, a hydrogen content of 3.77 percent by weight. Making it in the laboratory currently requires extreme conditions, around 250 kelvin and 300 megapascals of pressure using a diamond anvil cell, and takes about thirty minutes to form, which makes the method impractical for large scale production today. At still higher pressures the clathrate converts into denser structures with a higher hydrogen to water ratio, including, above about 2.3 gigapascals, a structure where the two are present in equal proportion. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/