In-situ one-step synthesis of activated Carbon@MIL-101 (Cr) composites for hydrogen storage

Abstract

Metal-organic frameworks (MOFs) unlocked new prospects of developing novel adsorbing materials for H2 storage. However, MOF porosity is not yet fully utilized. To compensate for that disadvantage, we synthesized MIL-101(Cr) MOF-based activated carbon AC@MIL-101 (Cr) composites using in situ hydrothermal method. Different amounts of activated carbon (AC) derived from fir bark were added to adjust the pore structure of the resulting MOF-based composites. The pore number and their sizes increased and decreased, respectively, after pristine MIL-101(Cr) was combined with AC. The surface area and pore volume of pristine MIL-101(Cr) were equal to 2299 m2/g and 1.06 cm3/g, respectively. These values became equal to 3367 m2/g and 1.64 cm3/g after AC was combined with MIL-101(Cr) to form AC@MIL-101(Cr) composite. The highest H2 uptake by AC@MIL-101(Cr) was equal to 6.93 wt % at 77 K and 40 bar. Such excellent hydrogen storage performance (a 32.3% increase than what was observed for unmodified MIL-101(Cr) material) was attributed to a synergy between AC and MIL-101(Cr).