Electrochemistry and electrocatalysis of myoglobin on electrodeposited ZrO2 and graphene-modified carbon ionic liquid electrode

In this paper, an electrodeposited zirconia (ZrO2) nanoparticle and graphene (GR) nanosheet-modified carbon ionic liquid electrode (CILE) was fabricated to get a modified electrode that denoted as ZrO2/GR/CILE, which was further used for the immobilization of myoglobin (Mb). The performances of ZrO2/GR/CILE were checked by scanning electron microscopy and electrochemical methods, and the results indicated the formation of nanocomposite on the electrode surface with increased surface area. Direct electrochemistry of Mb was realized on the modified electrode with a pair of well-defined quasi-reversible redox peaks appeared, which was ascribed to the typical electrochemical behaviors of Mb Fe(III)/Fe(II) redox couples. Therefore, the presence of ZrO2/GR on the electrode could provide a specific interface for accelerating the electron transfer of Mb with the underlying electrode. Electrochemical behaviors of Mb were carefully investigated with the electrochemical parameters calculated. Under the selected conditions, the Mb-modified electrode exhibited excellent electrocatalytic activity to the reduction of trichloroacetic acid in the concentration range from 0.4 to 29.0 mmol L−1 with a detection limit of 0.13 mmol L−1 (3σ).