Electrochemical Investigations of Hydrothermally Synthesized Porous Cobalt Oxide (Co ₃ O ₄ ) Nanorods: Supercapacitor Application

Abstract

Abstract Well‐crystalline porous cobalt oxide (Co 3 O 4 ) nanorods (NRs) were synthesized through hydrothermal method and applied as electro‐active electrode material for pseudo‐supercapacitors. At low calcination temperature of 300 °C, the porous and smooth morphology of Co 3 O 4 NRs were obtained whereas, the rod morphology changed to stacks of nanoparticles at high calcination at 500 °C. The Fourier transform infrared (FTIR) and Raman scattering spectroscopies revealed the formation of pure and good crystal quality porous Co 3 O 4 NRs. Brunauer‐Emmett‐Teller (BET) surface area analysis of porous Co 3 O 4 NRs showed the decrease of surface area and pore volume with the increase of calcination temperature. The charge storage ability, cycle stability and ion transport of the synthesized porous Co 3 O 4 NRs electrode were investigated by performing cyclic voltammetry (CV) in 6 M KOH electrolyte. As compared to Co 3 O 4 NRs‐500 °C electrode, the specific capacitance of ∼226.3 Fg −1 at a scan rate of ∼10 mVs −1 was achieved by the fabricated pseudo‐supercapacitors based on porous Co 3 O 4 NRs‐300 °C electrode. The synthesized porous Co 3 O 4 NRs electrode showed excellent stability by maintaining up to ∼76% capacity retention after 5000 cycles.