A huge challenge facing scientists is the development of adsorbent materials that exhibit ultrahigh porosity but maintain balance between gravimetric and volumetric surface areas for the onboard storage of hydrogen and methane gas—alternatives to conventional fossil fuels. Here we report the simulation-motivated synthesis of ultraporous metal–organic frameworks (MOFs) based on metal trinuclear clusters, namely, NU-1501-M (M = Al or Fe). Relative to other ultraporous MOFs, NU-1501-Al exhibits concurrently a high gravimetric Brunauer−Emmett−Teller (BET) area of 7310 m2 g−1 and a volumetric BET area of 2060 m2 cm−3 while satisfying the four BET consistency criteria. The high porosity and surface area of this MOF yielded impressive gravimetric and volumetric storage performances for hydrogen and methane: NU-1501-Al surpasses the gravimetric methane storage U.S. Department of Energy target (0.5 g g−1) with an uptake of 0.66 g g−1 [262 cm3 (standard temperature and pressure, STP) cm−3] at 100 bar/270 K and a 5- to 100-bar working capacity of 0.60 g g−1 [238 cm3 (STP) cm−3] at 270 K; it also shows one of the best deliverable hydrogen capacities (14.0 weight %, 46.2 g liter−1) under a combined temperature and pressure swing (77 K/100 bar → 160 K/5 bar).

Analogous to the way the Human Genome Project advanced an array of biological sciences by mapping the human genome, the Materials Genome Initiative aims to enhance our understanding of the fundamentals of materials science by providing the information we need to accelerate the development of new materials.This approach is particularly applicable to recently developed classes of nanoporous materials, such as metal-organic frameworks (MOFs), which are synthesized from a limited set of molecular building blocks that can be combined to generate a very large number of different structures. In this Perspective, we illustrate how a materials genome approach can be used to search for high-performance adsorbent materials to store natural gas in a vehicular fuel tank. Drawing upon recent reports of large databases of existing and predicted nanoporous materials generated in silico, we have collected and compared on a consistent basis the methane uptake in over 650 000 materials based on the results of molecular simulation. The data that we have collected provide candidate structures for synthesis, reveal relationships between structural characteristics and performance, and suggest that it may be difficult to reach the current Advanced Research Project Agency-Energy (ARPA-E) target for natural gas storage. Broader contextNatural gas, mostly methane, is an attractive replacement for petroleum fuels for automotive vehicles because of its economic and environmental advantages. However, it suffers from a low volumetric energy density, necessitating densication to yield reasonable driving ranges from a full fuel tank. Densication strategies in the market today, liquefaction and compression, require expensive and cumbersome vehicular fuel tanks and rell station infrastructure. If we are able to develop a nanoporous adsorbent material to store natural gas at ambient temperature and moderate pressure, one could envision a simple fuel tank that can be relled at home. Modern, advanced nanoporous materials are highly tunable, inundating researchers with practically innite possibilities of materials to synthesize and test for methane storage. The current research is focused on nding among these millions of possible materials one that can be used to store natural gas without using liquefaction or compression processes. In this Perspective, we adopt a computational approach to screen databases of over 650 000 nanoporous material structures. Using this nanoporous materials genome approach, we reveal relationships between structural characteristics and performance, and suggest that it may be difficult, if not impossible, to reach the current Advanced Research Project Agency-Energy (ARPA-E) target for natural gas storage using nanoporous materials.

Metal-organic frameworks (MOFs) can exhibit exceptionally high surface areas, which are experimentally estimated by applying the BET theory to measured nitrogen isotherms. The Brunauer, Emmett, and Teller (BET)-estimated nitrogen monolayer loading is thus converted to a "BET area," but the meaning of MOF BET areas remains under debate. Recent emphasis has been placed on the usage of four so-called "BET consistency criteria." Using these criteria and simulated nitrogen isotherms for perfect crystals, we calculated BET areas for graphene and 25 MOFs having different pore-size distributions. BET areas were compared with their corresponding geometrically calculated, nitrogen-accessible surface areas (NASAs). Analysis of simulation snapshots elucidated the contributions of "pore-filling" and "monolayer-formation" to the nitrogen adsorption loadings in different MOF pores, revealing the origin of inaccuracies in BET-calculated monolayer loadings, which largely explain discrepancies between BET areas and NASAs. We also find that even if all consistency criteria are satisfied, the BET calculation can significantly overestimate the true monolayer loading, especially in MOFs combining mesopores (d ≥ 20 Å) and large micropores (d = 10-20 Å), due to the overlap of pore-filling and monolayer-formation regimes of these two kinds of pores. While it is not always possible to satisfy all consistency criteria, it is critical to minimize the deviation from these criteria during BET range selection to consistently compare BET areas of different MOFs and for comparing simulated and experimental BET areas of a given MOF. To accurately assess the quality of a MOF sample, it is best to compare experimental BET areas with simulated BET areas rather than with calculated NASAs.