Cobalt oxide nanoparticles anchored to multiwalled carbon nanotubes: Synthesis and application for enhanced electrocatalytic reaction and highly sensitive nonenzymatic detection of hydrogen peroxide

Cobalt (II) dicobalt (III) oxide nanoparticles anchored to multiwalled carbon nanotubes were synthesized for the first time by a microwave decomposition method using cobalt nitrate as a precursor and multiwalled carbon nanotubes as a scaffold. The nanostructure was then employed as the modifier of a carbon paste electrode. The kinetics of the charge transfer process across the modified electrode/solution interface was studied. The modified electrode was then applied to fabricate an enzyme-less hydrogen peroxide biosensor. The mechanism and kinetics of the electrocatalytic reduction and oxidation reactions of hydrogen peroxide on the modified electrode surface were studied by cyclic voltammetry and chronoamperometry. The catalytic rate constants of the hydrogen peroxide electroreduction and electrooxidation processes by an active cobalt species, and the diffusion coefficient of hydrogen peroxide were reported. An amperometric method was developed for determination of hydrogen peroxide based on its electrocatalytic reduction with a sensitivity of 1002.8 mA mol−1 dm3 cm−2 and a limit of detection of 2.46 μmol dm−3. The sensor had the advantages of high electrocatalytic activity and sensitivity, with a simple fabrication method without complications of immobilization steps and using any enzyme or reagent.