Incorporation of UiO-66 into graphene foam for hydrogen storage applications

Abstract

The fabrication of application-specific metal-organic framework (MOF) composites has the potential to shift more towards hydrogen storage system integration. The in-situ growth of nano particles on a graphene surface is a common technique for synthesizing graphene-inorganic nanocomposites and in this study, a graphene foam (GF) / zirconium-based MOF (UiO-66) composite was prepared using a two-step solvothermal method. Brunauer, Emmett and Teller (BET) surface area as well as hydrogen uptake capacity were measured under cryogenic conditions and compared to the values for pristine UiO-66. The GF/UiO-66 composite had a BET surface area of 1073 m2.g-1 and a hydrogen uptake capacity of 1.1 wt% at 77 K and 1.2 bar pressure, compared to 1367 m2.g-1 and 1.5 wt%, respectively for pristine UiO-66 under the same conditions. Besides the values being compromised relative to pristine UiO-66, the two-step in-situ synthesis approach yielded a composite with enhanced BET surface area and H2 uptake relative to a composite obtained from a single step synthesis approach. The composites further exhibited better thermal stability than the pristine UiO-66 and show promise for the development of powdered MOF materials towards hydrogen storage system integration.