Highly efficient solid-state synthesis of Co3O4 on multiwalled carbon nanotubes for supercapacitors

Highlights: • Highly efficient solid-state synthesis of Co₃O₄ on NMWCNT is reported. • Morphology and structure are investigated by the aid of analytical techniques. • Elevated specific capacitance of 202 F/g at 1 A/g of current density was perceived. • Promising candidate for electrochemical storage. -- Abstract: Synthesizing hybrid nanostructures through green protocols continues to attract great attention since it offers atom economy, simple processing, and environmental friendliness; and avoids using harsh chemical reagents. Herein we report the assembly of cobalt oxide on nitrogen-doped multiwalled carbon nanotubes (Co₃O₄-NMWCNT) composite synthesized by a green protocol with mechanochemical grinding for supercapacitor applications. The structural and morphological properties of the composites were confirmed by the aid of X-ray diffraction (XRD) studies, Raman spectroscopy, and scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HR-TEM). The synthesized composite material exhibited tube-like morphology with the distribution of Co₃O₄ nanoparticles. Fabricated Co₃O₄-NMWCNT symmetric supercapacitor device was further investigated for its electrochemical properties, thereby leading a high specific capacitance 202 F/g at 1 A/g of current density, with 25 Wh/kg of energy density at 0.9 kW/kg of power density. Therefore, Co₃O₄-NMWCNT composite electrodes offer excellent capacitive performance for the energy storage system.