A Nernstian Biosupercapacitor.

We propose the very first 'Nernstian biosupercapacitor', a biodevice based on only one redox polymer: poly(vinyl imidazole- co-allylamine)[Os(bpy)₂Cl], and two biocatalysts. At the bioanode PQQ-dependent glucose dehydrogenase reduces the Os³⁺ moieties at the polymer to Os²⁺ shifting the Nernst potential of the Os³⁺/Os²⁺ redox couple to negative values. Concomitantly, at the biocathode the reduction of O₂ by means of bilirubin oxidase embedded in the same redox polymer leads to the oxidation of Os²⁺ to Os³⁺ shifting the Nernst potential to higher values. Despite the use of just one redox polymer an open circuit voltage of more than 0.45 V was obtained during charging and the charge is stored in the redox polymer at both the bioanode and the biocathode. By connecting both electrodes via a predefined resistor a high power density is obtained for a short time exceeding the steady state power of a corresponding biofuel cell by a factor of 8. [ABSTRACT FROM AUTHOR]