Electrodeposited ZnO@three-dimensional Graphene Composite Modified Electrode for Electrochemistry and Electrocatalysis of Myoglobin

A three-dimensional graphene (3DGR) was electrodeposited on carbon ionic liquid electrode (CILE) and further decorated with electrodeposited zinc oxide (ZnO) to get a ZnO@3DGR hybrid composite. Then myoglobin (Mb) was immobilized on the surface of ZnO@3DGR modified electrode with Nafion to prepare the biosensor named as Nafion/Mb/ZnO@3DGR/CILE. On cyclic voltammogram a pair of well-defined redox responses resulted from the electron transfer of Mb with the working electrode was got, which could be ascribed to the specific characteristics of ZnO@3DGR including porous macrostructure, biocompatibility, high conductivity and big surface area. Electrochemical parameters including the electron transfer coefficient (alpha) and the apparent heterogeneous electron transfer rate constant (k(s)) were got by electrochemical methods with the values as 0.31 and 0.76 s(-1). This biosensor showed excellent electrocatalysis to the electro reduction of trichloroacetic acid (TCA). A good linear relationship between the catalytic reduction peak current and TCA concentration was in the range from 0.5 to 30.0 mmol L-1 and the detection limit was 0.167 mmol L-1 (3 sigma). The results indicated that a third-generation electrochemical Mb biosensor with ZnO@3DGR/CILE was prepared and exhibited good stability with reproducibility.