Ultrahigh–surface area covalent organic frameworks for methane adsorption

Developing porous materials with ultrahigh surface areas for gas storage (for example, methane) is attractive but challenging. Here, we report two isostructural three-dimensional covalent organic frameworks (COFs) with a rare self-catenated <b>alb</b>-3,6-<i>Ccc</i>2 topology and a pore size of 1.1 nanometer. Notably, these imine-linked microporous COFs show both high gravimetric Brunauer-Emmett-Teller (BET) surface areas (~4400 square meters per gram) and volumetric BET surface areas (~1900 square meters per cubic centimeter). Moreover, their volumetric methane uptake reaches up to 264 cubic centimeter (standard temperature and pressure) per cubic centimeter [cm³ (STP) cm^-3] at 100 bar and 298 kelvin, and they exhibit the highest volumetric working capacity of 237 cm³ (STP) cm^-3 at 5 to 100 bar and 298 kelvin among all reported porous crystalline materials.