Facile and scalable route to sheets-on-sheet mesoporous Ni–Co-hydroxide/reduced graphene oxide nanocomposites and their electrochemical and magnetic properties

Abstract

A facile synthesis of sheets-on-sheet mesoporous Ni–Co-hydroxide/reduced graphene oxide (RGO) nanocomposites via the chemical decomposition of nickel cobalt hexacyanoferrate (NiCoHCF) complex is demonstrated. The chemical decomposition of NiCoHCF by NaOH resulted in the formation of Ni–Co-hydroxide directly on RGO that was confirmed by powder XRD analysis. The formation of Ni–Co-hydroxide nanosheets on RGO nanosheet was revealed using FE-SEM and HR-TEM analyses. The mesoporous nature of sheets-on-sheet Ni–Co-hydroxide/RGO nanocomposites was realized using BET surface area analysis and pore-size distribution. The electrochemical performance of Ni–Co-hydroxide/RGO nanocomposites with different weight ratios was evaluated using cyclic voltammetry, galvanostatic charge discharge measurements and electrochemical impedance spectroscopic analysis. The nanocomposite with a 1 : 1 ratio of Ni–Co-hydroxide and RGO exhibited a very high specific capacitance of 835 F g⁻¹ at 1 A g⁻¹ current density with an excellent capacity retention of 92% even after 5000 cycles. The magnetic properties of pristine Ni–Co-hydroxide and its nanocomposites with RGO were also investigated. The reported method is simple and scalable for growth of Ni–Co-hydroxide nanosheets over RGO nanosheets.