Anchoring cobalt oxide nanoparticles on to the surface multiwalled carbon nanotubes for improved supercapacitive performances

Abstract

The present work explored a novel, simple and low cost ‘dipping and drying’ process followed by a successive ionic layer adsorption and reaction (SILAR) method for the synthesis of cobalt oxide anchored multiwalled carbon nanotubes (Co₃O₄/MWNTs). Initially, MWNTs have been coated on a stainless steel substrate by a simple ‘dip and dry’ method, on which further deposition of cobalt oxide nanoparticles was carried out by the SILAR method. Our results confirm the uniform coating of Co₃O₄ nanoparticles having sizes less than 15 nm on the surface of MWNTs. Later, the electrochemical performance shows that, the Co₃O₄/MWNTs films exhibit a maximum specific capacitance of 685 F g⁻¹ in a 2 M KOH electrolyte at a scan rate of 5 mV s⁻¹ with high cycle stability of 73% over 5000 cycles. Moreover, lower electrochemical equivalent series resistance (11.25 mU) give rise to the superior performance. These results show, the potential of Co₃O₄/MWNTs composite electrodes in electrochemical supercapacitors.