Microwave-assisted synthesis of NiCo2O4–graphene oxide nanocomposites suitable as electrodes for supercapacitors

Abstract

Microwave irradiation combined with mild heating was demonstrated as a suitable synthetic method for the preparation of NiCo₂O₄ nanowires and NiCo₂O₄–graphene oxide nanocomposites. In both cases, the synthesis was carried out in just a few minutes, at relatively low temperatures and with a certain economy of reagents. In the particular case of the nanocomposites, NiCo₂O₄ was deposited in form of not only nanowires, but also ultrafine nanoparticles on the surface of graphene oxide sheets due to the preferred activation of these sheets under microwave irradiation. The nanocomposites exhibited a superior performance to NiCo₂O₄ nanowires as electrodes in pseudocapacitors with capacitance retentions of nearly 735 F g⁻¹ at current densities of up to 33 A g⁻¹.