Background: Carbon-based nanomaterials, especially carbon nitride (C3N4) has attracted
tremendous interest in biosensor applications. Meanwhile, the mechanism of redox protein sensing
and related electrocatalytic reactions can provide a valid basis for understanding the process of biological
Objective: The aim of this paper is to construct a new electrochemical enzyme sensor to achieve direct
electron transfer of myoglobin (Mb) on CILE surface and display electrocatalytic reduction activity
to catalyze trichloroacetic acid (TCA) and H2O2.
Methods: The working electrode was fabricated based on ionic liquid modified Carbon Paste Electrode
(CILE) and C3N4 nanosheets were modified on the CILE surface, then Mb solution was fixed
on C3N4/CILE surface and immobilized by using Nafion film. The as-prepared biosensor displayed
satisfactory electrocatalytic ability towards the reduction of TCA and H2O2 in an optimum pH 7.0
Results: The results indicated that C3N4 modified electrode retained the activity of the enzyme and
displayed quasi-reversible redox behavior in an optimum pH 7.0 buffer solution. The electrochemical
parameters of the immobilized Mb on the electrode surface were further calculated with the results of
the electron transfer number (n) as 1.27, the charge transfer coefficient (α) as 0.53 and the electrontransfer
rate constant (ks) as 3.32 s-1, respectively. The Nafion/Mb/C3N4/CILE displayed outstanding
electrocatalytic reduction activity to catalyze trichloroacetic acid and H2O2.
Conclusion: The Nafion/Mb/C3N4/CILE displayed outstanding electrocatalytic reduction, which
demonstrated the promising applications of C3N4 nanosheet in the field electrochemical biosensing.