Electrochemical properties of enzyme electrode covalently immobilized on a graphite oxide/cobalt hydroxide/chitosan composite mediator for biofuel cells

A critical factor for the performance of a biofuel cell is an immobilization of the redox enzyme for continuous catalytic reaction and efficient electron transfer. However, the main obstacle associated with enzyme electrode is the reduced surface area for the accommodation of enzymes, leading to poor power output. This study aimed to optimize the efficient electrical communication for glucose oxidase (GOx) on the surface of a graphite oxide/cobalt hydroxide/chitosan composite as mediator, thereby enhancing the generation of power output. Immobilization efficiency was affected by the different concentrations of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC)/N-hydroxysuccinimide (NHS). Also, the surface of enzyme electrode was observed by XPS, Raman, and AFM, respectively. The electrochemical characterization showed that the immobilized GOx possesses the highest activity at EDC:NHS(40:80 mM) concentration. The power output under the optimal condition was found to be 2.24 mWcm⁻² of power density using the three-electrode cell in 0.1 M PBS solution at room temperature.