Graphene-coated carbon fiber cloth for flexible electrodes of glucose fuel cells

In this work, we fabricated flexible electrodes for a miniaturized, simple structured, and flexible glucose biofuel cell (BFC) using a graphene-coated carbon fiber cloth (GCFC). The areas of the anode and cathode electrodes were 3 x 10mm(2). The anode area was coated with the enzyme glucose oxidase, and the cathode area was coated with the enzyme bilirubin oxidase. No ion-exchange film was needed because glucose oxidase selectively oxidizes glucose and bilirubin oxidase selectively reduces oxygen. The power density of the BFC with GCFC electrodes in a phosphate buffer solution of 200mM glucose solution at room temperature was 34.3 mu W/cm(2) at 0.43V. The power density of a BFC using carbon fiber cloth (CFC) without graphene modification was 18.5 mu W/cm(2) at 0.13V. The BFC with the GCFC electrode continued to function longer than 24 h with a power density higher than 5 mu W/cm(2). These effects were attributed to the much larger effective surface areas of the GCFC electrodes that maintain more enzymes than those of the CFC electrodes. (C) 2016 The Japan Society of Applied Physics