Synergic effect of physically-mixed metal organic framework based electrodes as a high efficient material for supercapacitors

Porous materials have been recently used for the development of hybrid supercapacitors (HSCs) because they can facilitate rapid electron and mass transportation for energy storage purposes. Among porous materials, metal-organic frameworks (MOFs) have attracted attention as working electrodes for HSCs owing to their controllable morphology and topology, large pore and porosity size, high specific surface area, and fascinating physicochemical properties. In this study, by using an easy and cost-effective method, a copper-based MOF (Cu-MOF), a nickel-based MOF (Ni-MOF), and a cobalt-based MOF (Co-MOF) were physically combined and employed as a working electrode for supercapacitors. They were analyzed in a three-electrode system. The cyclic voltammetry (CV) measurement at the scan rate of 10 mV s−1 in 6 M KOH aqueous electrolyte showed the specific capacitances (Cs) of 316, 898, and 1823 F g−1 for Co-MOF&Cu-MOF, Ni-MOF&Co-MOF and Ni-MOF&Cu-MOF electrode, respectively. The Ni-MOF&Cu-MOF showed the highest Cs arising from the synergic effects between MOFs and the presence of multiple valence states that increases the contact area for electrolytes in the nanocomposites. This strategy can open a new window to the high performance material and facile fabrication of binary MOFs electrodes for energy storage systems.