Improved sensing of dopamine and ascorbic acid using a glassy carbon electrode modified with electrochemically synthesized nickel-cobalt hexacyanoferrate microparticles deposited on graphene

We report on the preparation of a nanocomposite by an electrochemical redox reaction in which graphene oxide is reduced to graphene while nickel-cobalt hexacyanoferrate (III) microparticles are simultaneously formed by oxidation. The microparticles deposit uniformly on the surface of graphene sheets, and the resulting nanocomposite was characterized by scanning electron microscopy, energy dispersive X-ray studies, cyclic voltammetry, and differential pulse voltammetry. Electrochemical studies using a glassy carbon electrode showed the material to possess superior electrocatalytic activity in terms of the oxidation of dopamine (DA) and ascorbic acid (AA). Calibration plots were established for DA in the concentration range from 0.2 to 500 μM (at a potential of 280 mV), and for AA from 0.5 to 200 μM and from 200 to 2,000 μM, (at a potential of 100 mV). These linear ranges are much wider than those of most modified electrodes reported before. (author)