Direct Electrochemistry of Myoglobin on Three-Dimensional Graphene- Nickel Oxide Modified Electrode and Electrocatalytic Detection of Trichloroacetic Acid

Background: Graphene is easy to aggregate by π-π and Van der Waals interaction between nanosheets, which diminishes the accessible area and limits its real applications in electrochemisty. The construction of three-dimensional graphene and its related nanocomposite is an effective path to overcome this problem.

Objective: The aim of this paper is to study the direct electrochemistry of myoglobin on threedimensional graphene-nickel oxide modified electrode and its electrocatalytic detection of trichloroacetic acid.

Method: Electrodeposition approach is used to synthesize three-dimensional graphene-nickel oxide nanocomposite. Scanning electron microscopy is used to characterize the morphology of the materials. Electrochemical impedance spectroscopy and cyclic voltammetry are carried out to investigate the electrode performance. Electrocatalysis of myoglobin modified electrode for trichloroacetic acid are conducted by cyclic voltammetry.

Results: A three-dimensional graphene/nickel oxide nanostructure is synthesized by electrodeposition directly on carbon ionic liquid working electrode. Direct electrochemistry of myoglobin on threedimensional graphene-nickel oxide modified electrode is successfully achieved with a pair of enhanced redox peaks. The electrocatalytic detection of trichloroacetic acid is established with a wider linear range (0.5~32.0 mmol L-1) and a lower limit of detection (0.16 mmol L-1).

Conclusion: This electrochemical trichloroacetic acid biosensor exhibits properties such as high sensitivity and good reproducibility with better stability, which indicates that the three-dimensional graphene/ nickel oxide nanocomposite plays a positive role in the field of third-generation electrochemical enzyme sensor construction.