Direct electron transfer of horseradish peroxidase at Co3O4–graphene nanocomposite modified electrode and electrocatalysis

Abstract

In this paper, the mixture of Co3O4–graphene nanocomposite and horseradish peroxidase (HRP) was spread on the surface of carbon ionic liquid electrode (CILE). Then, Nafion film was used for the immobilization. The results of spectroscopy proved that HRP kept up its native structure in the complex material. Direct electrochemistry of HRP resulted in a couple of quasi-reversible redox waves on cyclic voltammograms, reflecting the realization of direct electron transfer of HRP with electrode. The improvement in electrochemical responses was due to the usage of highly conductive Co3O4–graphene nanocomposite with biocompatible interface. Electrochemical parameters such as the electron transfer coefficient (α) was estimated as 0.47, and the apparent heterogeneous electron transfer rate constant (ks) was calculated as 2.90 s−1. The HRP modified electrode exhibited good electrochemical catalytic ability toward the reduction of trichloroacetic acid and NaNO2. As a consequence, an updated third-generation electrochemical HRP biosensor with Co3O4–GR/CILE was constructed successfully.