Hydrogen storage porous structure

Concurrent stream of the development of nanomaterials for solid-state hydrogen storage comes from century-old studies of porous materials for absorption of gasses, among them porous carbon phases, better known as activated carbon. Absorption of gases in those materials follows different principles from just discussed absorption in metals. Instead of chemisorption of gas into the crystalline structure of metals, it undergoes physisorption on crystalline surfaces and in the porous structure formed by crystals. The gases have also been known to be phy-sisorbed on fine carbon fibers. 

There is also another topological limit on C H ratio. Physisorption proceeds only in the monolayer above the boiling point of hydrogen, and the adsorption must follow the Langmuir isotherm. Hence, the storage capacity depends on the pressure of H2 gas above the carbon surface at a fixed temperature. It is also greatly limited by available SSA of carbon phase as provided by porous structure. 

Different classes of porous materials possessing different structure and composition have been discussed for hydrogen storage applications. For all materials a... 

Chun, H., Dybstev, D.N., Kim, H., and Kim, K. 2005. Synthesis, x-ray crystal structures, and gas sorption properties of pillared square grid nets based on paddle-wheel motifs Implications for hydrogen storage in porous materials. Chemistry—A European Journal 11, 3521-3529. 

Lan J, Cao D, Wang W, Ben T, Zhu G (2010) High-capacity hydrogen storage in porous aromatic frameworks with diamond-like structure. J Phys Chem Lett 1 978-981... 

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