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)(2)Cl], and two biocatalysts. At the bioanode PQQ‐dependent glucose dehydrogenase reduces the Os(3+) moieties at the polymer to Os(2+) shifting the Nernst potential of the Os(3+)/Os(2+) redox couple to negative values. Concomitantly, at the biocathode the reduction of O(2) by means of bilirubin oxidase embedded in the same redox polymer leads to the oxidation of Os(2+) to Os(3+) 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.