Electrochemical capacitance properties of cobalt oxide entangled over MWCNT and cobalt oxide AC composites

Composites of cobalt oxide with activated carbon (AC) and multi wall carbon nano tubes (MWCNTs) were synthesised using hydrothermal method. X-ray diffraction and scanning electron microscopy (SEM) has revealed the Co3O4 nano phase well embedded over the AC and MWCNTs matrices. Materials were further characterised using FTIR measurements. Cyclic voltammetry and charge discharge experiments were carried out in 1M KOH solution. Both the materials have shown superior electrochemical properties and good long time cycle ability. The Co3O4 with MWCNTs composite (Co3O4/MWCNTs) has shown better electrochemical characteristics compared to the composite of Co3O4 with AC (Co3O4/AC) due to the symmetric entanglement of the materials all over the MWCNT surface. The discharge specific capacitance of Co3O4/AC and Co3O4/MWCNTs composites was obtained as 620 and 788 Fg−1 respectively. The electrochemical performance of the materials was modelled using electrochemical impedance modelling and the results revealed the presence of unsaturated surface charge over the composite electrode surface. [Display omitted] •Co3O4/AC and Co3O4/MWCNT composites were hydrothermally synthesised.•Electrochemical properties of the materials were investigated•Specific capacitance of 620 and 788 Fg−1 at 4 Ag−1 obtained for two composites.•Energy density of 21.6 and 27.4Whkg−1 obtained for Co3O4/AC and Co3O4/MWCNT.•Mechanism of variation of pseudocapacitance between the materials was investigated.