Electrochemical Investigations of Hydrothermally Synthesized Porous Cobalt Oxide (Co₃O₄) Nanorods: Supercapacitor Application

Well-crystalline porous cobalt oxide (Co₃O₄) 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 Co₃O₄NRs 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 Co₃O₄NRs. Brunauer-Emmett-Teller (BET) surface area analysis of porous Co₃O₄NRs 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 Co₃O₄NRs electrode were investigated by performing cyclic voltammetry (CV) in 6 M KOH electrolyte. As compared to Co₃O₄NRs-500 °C electrode, the specific capacitance of ∼226.3 Fg⁻¹at a scan rate of ∼10 mVs⁻¹was achieved by the fabricated pseudo-supercapacitors based on porous Co₃O₄NRs-300 °C electrode. The synthesized porous Co₃O₄NRs electrode showed excellent stability by maintaining up to ∼76% capacity retention after 5000 cycles.