Supercapacitor and photocatalytic performances of hydrothermally-derived Co3O4/CoO@carbon nanocomposite

Abstract

Cobalt oxide (Co₃O₄/CoO) nanoparticle-embedded carbon matrix (Co₃O₄/CoO@carbon) was synthesized by pyrolysis of cobalt-salen complex ([Co(salen)]) followed by hydrothermal treatment. The X-ray diffraction, Raman and Fourier transform infra-red spectroscopies confirmed the presence of Co₃O₄/CoO in the carbon matrix. The scanning electron microscopy observation showed highly agglomerated spike-like grains. The TEM observation confirmed that the Co₃O₄/CoO grains were embedded in the carbon matrix. The supercapacitor studies conducted on the Co₃O₄/CoO@carbon matrix revealed a specific capacity of 324 C g⁻¹ at 1 A g⁻¹ in 1 M KOH. The Co₃O₄/CoO@carbon electrode also exhibited long-term life cycle with a high Coulombic efficiency of 96%. It is believed that the carbon present in Co₃O₄/CoO acted as a conductive nano-network, leading to such a high supercapacitor performance. The Co₃O₄/CoO@carbon material was also tested for its catalytic property, and it was found that the prepared material exhibited excellent photocatalytic degradation of azure A dye.