Yaghi, O’Keeffe and collaborators have achieved inner (BET) surface areas of MOFs exceeding 6,000 m2 per gramme. Made of Zn4O(CO2)6 complexes and organic linkers, the lightweight MOF 210 offers over 2000 m2 of adsorption opportunity per cubic centimetre to gases such as hydrogen, methane, or carbon dioxide. The outside-facing equivalent of such surface capacity is impossible to realise as nanoparticles fail to form stable dry powders at the required size – cube-shaped particles would require edge lengths of well under 6 nm, and normal handling would fail to achieve perfect use of all facial surfaces.
MOFs’ total porosity, easier material handling and tailored design of structure, pore shapes, and sizes make for far superior potential in gas storage and sequestration applications.
Image source: www.sciencemag.org, Supplemental information to M. O’Keeffe, O. M. Yaghi et al., DOI 10.1126/science.1192160