The study of electrochemical hydrogen storage behavior of the UiO-66 framework on the metal/reduced graphene oxide substrate

Abstract

Feasible and safe storage of hydrogen as a clean and renewable energy carrier, is one of the main challenges to be tackled using highly efficient hydrogen storage materials. A new nanocomposite with a zirconium-based metal–organic framework is synthesized for the first time to improve the hydrogen storage capacity of the graphene oxide used to design graphene layers with metal. To this end, graphene oxide (GO) is combined with some metal ions (M), including Cu2+, Ni2+, Co2+and Ag+. The results of hydrogen storage capacity show that among different M/rGO, the introduction of Ag is the best choice. Eventually, the hydrogen storage capacity of 25 wt% Ag/rGO is 1600 mAhg−1, which has had an increase of more than 4 times as compared to the GO electrode. Besides, UiO-66/Ag/rGO nanocomposites are prepared at room temperature. The hydrogen storage capacity of UiO-66/Ag/rGO (MUiO-66/MAg/rGO = 5:1), reached from 250 mAhg−1 (0.94 wt%) to 6100 mAhg−1 (22.94 wt%) after 20 cycles, which was significantly enhanced; namely, about 3.8 times higher than Ag/rGO sample and approximately 2 times higher than UiO-66 sample. Furthermore, adding Ag/rGO to UiO-66 improved the porosity resulting in increasing the specific surface area of UiO-66/Ag/rGO (473 m2g−1) significantly, as compared to pure Ag/rGO (27.1 m2g−1).