A brief look at the theoretical studies on the storage of hydrogen gas in metal-organic frameworks

Metal-organic frameworks are periodic materials with crystalline lattices which are mainly formed by bonding metal ions with organic ligands[1]. The structural building blocks of MOFs can be combined to produce an almost unlimited number of materials. Each of these compounds naturally exhibits different properties in the absorption of various gases, including hydrogen. The problem is that synthesizing and evaluating the properties of all these compounds is time consuming and costly. For example, in 2012 Wilmer et al managed to identify 137953 hypothetical MOFs through computations and using only 102 building blocks[2]. This huge number of compounds shows that the use of computational tools rather than experimental work is more logical for high-throughput screening. However, the use of conventional simulation techniques in this area, such as Molecular dynamics (MD), Grand canonical Monte Carlo (GCMC) and Density functional theory (DFT), somewhat reduced the complexity of this massive amount of materials, but these methods do not appear to be fast enough to find ideal structural constituents and conventions. Therefore, in addition to the simulation methods used for phenomenology, in recent years the modeling of the gas absorption process in the MOFs has also been considered. Methods such as Quantitative structure- property relationships are proposed to predict the absorption of various gases such as methane, nitrogen, carbon dioxide and hydrogen based on the structure of the MOFs. Eventually, these models will be able to predict the amount of hydrogen uptake at high accuracy in the shortest time, as well as the rules and procedures for designing higher-efficiency MOFs[3].