Bioenergy and Biofuels

Applied Microbiology and Biotechnology

, Volume 96, Issue 3, pp 841-849

Prolongation of electrode lifetime in biofuel cells by periodic enzyme renewal

  • S. RubenwolfAffiliated withLaboratory for MEMS Applications, Department of Microsystems Engineering—IMTEK, University of Freiburg
  • , S. SanéAffiliated withLaboratory for MEMS Applications, Department of Microsystems Engineering—IMTEK, University of Freiburg
  • , L. HusseinAffiliated withFreiburg Materials Research Centre (FMF), University of FreiburgLaboratory for Sensors, Department of Microsystems Engineering—IMTEK, University of Freiburg
  • , J. KestelAffiliated withLaboratory for MEMS Applications, Department of Microsystems Engineering—IMTEK, University of Freiburgifm electronic GmbH
  • , F. von StettenAffiliated withLaboratory for MEMS Applications, Department of Microsystems Engineering—IMTEK, University of Freiburg
  • , G. UrbanAffiliated withFreiburg Materials Research Centre (FMF), University of FreiburgLaboratory for Sensors, Department of Microsystems Engineering—IMTEK, University of Freiburg
  • , M. KruegerAffiliated withFreiburg Materials Research Centre (FMF), University of FreiburgLaboratory for Sensors, Department of Microsystems Engineering—IMTEK, University of Freiburg
  • , R. ZengerleAffiliated withLaboratory for MEMS Applications, Department of Microsystems Engineering—IMTEK, University of FreiburgBIOSS Centre for Biological Signalling Studies, University of Freiburg
  • , S. KerzenmacherAffiliated withLaboratory for MEMS Applications, Department of Microsystems Engineering—IMTEK, University of Freiburg Email author 

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Abstract

Enzymatically catalyzed biofuel cells show unique specificity and promise high power densities, but suffer from a limited lifetime due to enzyme deactivation. In the present work, we demonstrate a novel concept to extend the lifetime of a laccase-catalyzed oxygen reduction cathode in which we decouple the electrode lifetime from the limited enzyme lifetime by a regular resupply of fresh enzymes. Thereto, the adsorption behavior of laccase from Trametes versicolor to buckypaper electrode material, as well as its time-dependent deactivation characteristics, has been investigated. Laccase shows a Langmuir-type adsorption to the carbon nanotube-based buckypaper electrodes, with a mean residence time of 2 days per molecule. In a citrate buffer of pH 5, laccase does not show any deactivation at room temperature for 2 days and exhibits a half-life of 9 days. In a long-term experiment, the laccase electrodes were operated at a constant galvanostatic load. The laccase-containing catholyte was periodically exchanged against a freshly prepared one every second day to provide sufficient active enzymes in the catholyte for the replacement of desorbed inactive enzymes. Compared to a corresponding control experiment without catholyte exchange, this procedure resulted in a 2.5 times longer cathode lifetime of 19 ± 9 days in which the electrode showed a potential above 0.744 V vs. normal hydrogen electrode at 110 μA cm−2. This clearly indicates the successful exchange of molecules by desorption and re-adsorption and is a first step toward the realization of a self-regenerating enzymatic biofuel cell in which enzyme-producing microorganisms are integrated into the electrode to continuously resupply fresh enzymes.

Keywords

Enzymatic biofuel cell Laccase Lifetime Long-term stability Adsorption Buckypaper