Bifunctional rGO-NiCo₂S₄MOF hybrid with high electrochemical and catalytic activity for supercapacitor and nitroarene reduction

The hexagonal NiCo2S4 hierarchical nanostructure was nucleated on the reduced graphene oxide (rGO) sheets using a simple hydrothermal method for use it as an electrode material for supercapacitor applications. Benefiting the synergistic effects from the hierarchical architecture of NiCo2S4 and outstanding conductivity of rGO, the hybrid rGO-NiCo2S4 composites provided many advantages such as increased electrolyte diffusion pathways, fast electron transport, and ample active sites. Thus, the hybrid rGO-NiCo2S4 composites presented a higher specific capacitance (972 F/g), compared with bare NiCo2S4 (716 F/g), at the current density of 1 A/g. Using the prepared nanomaterials, the asymmetric supercapacitor devices were constructed in the form of the 2-electrodes scheme. Remarkably, the rGO-NiCo2S4 based device demonstrated the excellent energy-storage characteristics with a higher specific capacitance (208 F/g) than that of the bare NiCo2S4 based device (86 F/g). After 2000 cycles, the rGO-NiCo2S4 supercapacitor device revealed an excellent cyclic stability with 94.1% of the capacitance retention at the current density of 3 A/g. Moreover, hybrid rGO-NiCo2S4 showed an admirable catalytic activity for nitroarene reduction. These findings suggest that the prepared rGO-NiCo2S4 MOF can be served as an excellent bifunctional electrocatalyst for the high-performance supercapacitor and the nitroarene reduction applications.