A Glucose Fuel Cell with Graphene-Coated Carbon Fiber Cloth

Enzymatic glucose biofuel cells that generate power in human body fluids have been strongly demanded to supply electric power to microelectric systems such as heart pacemakers. This is because they work under mild conditions of room temperature, neutral pH and atmospheric pressure, which make them amenable to the human body. Porous carbon electrodes have been commonly used in glucose biofuel cells [1]. However, it was not very easy to avoid release of enzymes form these porous carbon electrode during operation of the biofuel cells. In addition, these porous carbon films were not flexible, and they were easily fractured. On the other hand, a carbon fiber woven fabric (CF) has been reported to have high flexibility and conductivity. Moreover, there were some trials to deposit graphene on each carbon fibers in CF, and it is called as graphene-coated carbon fiber cloth(GC) [2]. Thus, it is considered to be possible to increase the effective surface areas to absorb more enzymes on GC surface. In this study, a glucose fuel cell was fabricated using GC as flexible electrodes in glucose biofuel cells. The SEM image of the GC used in this study is shown in Fig. 1. Many nanostructures were observed on carbon fibers. We used this GC as the anode and cathode of the fabricated micro biofuell cells, and the area of the anode and cathode electrodes were 3 × 10 mm 2 , respectively. The anode was modified with glucose oxidase (GOD) and ferrocene. The cathode was modified with bilirubin oxidase (BOD). Figure 2 shows comparison of the relationship of the power density and voltage of biofuell cells using GC or CF. The power was measured by immersing the biofuel cells in phosphate buffer solution with 100 mM glucose at room temperature. The maximum power for the CF biofuel cell was 16.3 μW / cm 2 at 0.07 V, and the maximum power for GC biofuel cell was 30.7 μW / cm 2 at 0.096 V. These results indicated the advantages of using GC on flexible glucose biofuel cells. [1] M. Togo, A. Takamura, T. Asai, H. Kaji, M. Nishizawa, Electrochim. Acta 52 (2007) pp.4669–4674. [2] http://incu-alliance.co.jp/