Synthesis of a new cathode redox polymer for high performance in biofuel cells

Abstract

High potential and fast electron transfer of a cathode mediator are significant factors for improving the performance of biofuel cells. This paper reports the first synthesis of a cathode redox polymer that is a coordination complex of poly (acrylic acid-vinylpyridine-acryl amide) (PAA-PVP-PAA) and [Os(4,4′-dicarboxylic acid-2,2′-bipyridine)2Cl2]/+ (E° = 0.48 V versus Ag/AgCl). Bilirubin oxidase can be easily incorporated into this polymer matrix, which carried out the four-electron oxygen under typical physiological conditions (pH 7.2, 0.14 M NaCl, and 37°C). This new polymer showed an approximately 0.1 V higher redox potential than existing cathode mediators such as PAA-PVI-[Os(dCl-bpy)2Cl]+/2+. In addition, we suggest increasing the polymer solubility with two hydrophilic groups present in the polymer skeleton to further improve fast electron transfer within the active sites of the enzyme. The maximum power density achieved was 60% higher than that of PAA-PVI-[Os(dCl-bpy)2Cl]+/2+. Furthermore, high current density and electrode stability were confirmed for this osmium polymer, which makes it a promising candidate for high-efficiency biofuel cells.