Promoting hydrogen storage in clathrate hydrates – PhySH

Clathrate hydrates (or gas hydrates), are nanoporous cristalline materials composed of water molecules self-assembled into cages and stabilized by the presence of small guest atoms or molecules encapsulating within the water host lattice. Clathrate hydrates are found naturally on Earth in deep ocean regions and in permafrost (Siberia, Alaska, Arctic) mainly as methane hydrates. They are also expected to exist on celestial bodies of the solar system (comets, satellites, planets). This natural occurrence makes them relevant for many geophysical and astrophysical applications. Gas hydrate is also one of the most promising material for hydrogen storage due mainly to its environmentally limited impact, to its soft temperature and pressure formation conditions and storage capacities and to its substantial hydrogen content. However, hydrogen storage in clathrate hydrates faces difficulties related to the decrease of storage capacities (when used along with promoters) and to slow formation kinetics. Ionic guest molecules are new promising promoter to develop H2 storage material in the gas hydrate framework but very few studies have been done on these ionic hydrates. The PhySH project falls within this scope. New clathrate hydrate co-including ionic and non-ionic guest molecules will be designed to optimize the hydrogen storage properties. To achieve this objective, the scientific program combines theoretical (static and dynamics calculations from first-principles simulations) and experimental approaches (Raman spectroscopy and neutron diffraction) to deal with the key factors of hydrogen hydrates that are thermodynamic stability and kinetic properties of formation.