Facile MOF-derived NiCo2O4/r-GO nanocomposites for electrochemical energy storage applications

• MOFs-derived Co-Ni hollow cubic structures were obtained by a heat treatment method. • Synthesis of nanostructured NiCo 2 O 4 /r-GO hybrid composites derived from the chronoamperometry method. • Excellent electrochemical performance of NiCo 2 O 4 nanocubes and NiCo 2 O 4 /r-GO hybrids as cathodes in a three-electrode system. • Enhanced capacity performance and reusability thanks to synergistic effects between GO and metal oxide in hybrid nanocomposite. In this work, an easy, cost-effective and scalable procedure combining electric double layer-based nanomaterials as reduced graphene oxide (r-GO) and pseudo-capacitive cubical NiCo 2 O 4 based-metal organic frameworks (MOFs) for the production of promising nanostructured electrodes for electrochemical energy storage devices was reported. r-GO as an electrical double layer-based carbonaceous material was used together with MOF-derived porous materials to enable the use of both types of energy storage processes: electric double layer and faradaic reactions within a single nanostructured electrode. r-GO as a conductive network/material should facilitate the transport of electrons during cycling, whereas the porous structure of the NiCo 2 O 4 metal oxide would improve the conductivity by means of the easy diffusion of the electrolyte into the electrode nanocomposite. The electrochemical performance of bare NiCo 2 O 4 nanocubes and NiCo 2 O 4 /r-GO composites were investigated by cyclic voltammetry (CV), galvanostatic charge/discharge (C/D) and electrochemical impedance spectroscopy (EIS). Besides, the NiCo 2 O 4 /r-GO nanocomposite was directly constructed on nickel foam showing an optimal adhesion even in the absence of a polymeric binder. This method allows the use of these nanocomposites as cathodes for electrodes with remarkable specific capacitances as large as 402F/g and 786F/g at a current density of 1 A/g for bare NiCo 2 O 4 -based MOFs and NiCo 2 O 4 -based MOFs/r-GO hybrid nanocomposites, respectively. Besides, it is worth noting that the NiCo 2 O 4 /r-GO-based electrode has an outstanding stability, with capacity losses only of ca. 11% after very long operation periods (>2000 cycles).