Enzymatic Biofuel Cells using Glucose as a Fuel

Abstract

Abstract: Fuel cells using glucose as a fuel are promising for portable and implantable energy devices because glucose is used as an energy source in most organisms, and not hazardous to human health. Several catalysts have been used to oxidize glucose such as noble metals, metal ad-atoms, redox dyes, microorganisms and enzymes. In this article, we focus on enzymatic fuel cells. For effective electron transfer between an enzyme and an electrode, mediators are generally used. However, when mediators are attached to polymers to form redox polymers, electron conduction through the redox polymer becomes the rate-limiting step in the overall electrode reactions, and limits the current density. To obtain high current density, we have proposed a high-surface-area three-dimensional enzyme electrode made of redox-polymer-grafted carbon black. The effectiveness of the electrode was verified by experiments and a mathematical model. The model calculation suggests that an increase in the surface coverage of the enzyme allows an increase in the current density to the order of 10² mA/cm², which allows biofuel cells to be used in portable energy devices. In addition, the performance of a membrane-electrode assembly-style biofuel cell using the electrode was demonstrated.