A biocatalyst containing chitosan and embedded dye mediator adopted for promoting oxidation reactions and its utilization in biofuel cells

A glucose oxidase (GOx) based biocatalyst combined with a methyl red (MR) mediator is developed to improve the electron transfer capability of the GOx-based biocatalyst. As a support to the biocatalyst, chitosan coated carbon nanotube (CNT/chitosan) are used, while the MR mediator and GOx are well immobilized onto the CNT/chitosan due to the strong organic material capturing ability of chitosan (CNT/chitosan/MR/GOx). The stable immobilization of MR and GOx is confirmed by spectroscopic method and electrochemical characterization is performed to prove the viability as the biocatalyst promoting the anodic reactions in an enzymatic biofuel cell (EBC). Based on the evaluations, CNT/[Chitosan-MR]/Chitosan/GOx shows the relatively excellent onset potential (−0.04 V vs. Ag/AgCl) and peak current density (169 μA cm⁻²). This is because the catalyst follows up well the onset potential of MR determining the onset potential of the catalyst and the considerable amounts of GOx are immobilized by chitosan's strong capturing capabilities. When the biocatalyst is used, the EBC shows excellent electrical performances with an open circuit voltage of 0.64 V and power density of 93 μW cm⁻².