Enhancing hydrogen storage in MOF/graphene composites: The impact of graphene oxide and porous graphene oxide on adsorptive performance

Abstract

This study presents the first experimental comparison of MOF/GO composites for hydrogen adsorption at near- ambient temperatures, emphasizing the critical role of two-dimensional (2D) graphene materials-specifically graphene oxide (GO) and porous graphene oxide (pGO)-on the surface area, pore size, and the adsorptive hydrogen storage properties of the composites. UiO-67 was chosen as the MOF due to its high surface area and excellent stability. Notably, we observed a 15.8 % and 27.4 % increase in hydrogen uptake for UiO-67/GO and UiO-67/pGO composites, respectively, at 77 K and 1 bar. The higher enhancement with UiO-67/pGO is attributed to the incorporation of porous GO compared to nonporous GO. Moreover, compared to UiO-67/5wtGO with a dominant pore size of 11 & Aring;, UiO-67/pGO has a dominant pore size of 5.7 & Aring;-within the optimal range for hydrogen storage at 77 K. Interestingly, at near ambient temperatures, the UiO-67/GO composite exhibited significantly higher hydrogen uptake than both UiO-67/pGO and pristine UiO-67. Despite the higher surface area of UiO-67/pGO, the abundant oxygen moieties on GO surfaces were more influential in enhancing hydrogen storage performance at elevated temperatures.