After creating a biofuel cell capable of generating electricity from the photosynthesis of a cactus (1), researchers from the Paul Pascal Research Centre of the CNRS (CRPP) are developing the most powerful and smallest biofuel cell ever. Two teams driven by Nicolas Mano and Philippe Poulin successful transition from producing stockpiles far between 1μW/cm ² and 50 μW / cm ² at 740 μW / cm ² through the development of innovative electrodes. This research represents a major step in the integration perspective of stockpiles to include therapeutic devices. These results were published in the journal Nature Communications on April 12, 2010.
In general, improving the performance of electrochemical devices (sensors, stockpiles, actuators ...) requires the design of electrode materials which meet the requirements of increasingly stringent. The transport of material in the electrode should be as low as possible and the specific surface material from the electrode should it be very important to increase the surface reaction. How to play with these two parameters to increase the amount of current supplied by the battery?
The limitation of mass transport can be notably reduced by making small electrodes called micro-electrodes. To increase the specific surface of the electrode, a current research challenge is to increase its porosity. This amounts to increasing the reactive surface of the electrode without changing its dimensions. This is a first team that "stockpiles" and the team "Nanotube" CRPP have achieved by developing new fiber microelectrodes based on carbon nanotubes of high porosity, thus displaying a large surface area ( »300 m2 / g), whose diameter is only a few microns. By using these fibers to the anode and cathode, the researchers have developed the most powerful biopile glucose/O2 and smallest conducted to date, generating an electric current of unmatched power of 740 μW. cm-2 at + 0.57V.
To highlight the performance of this biopile, researchers first studied the reduction of O2 and made comparisons with the best competing systems made with carbon fibers. As shown in Figure 1, after modification with bioélectrocatalyseurs (polymer + enzyme), it was possible to reduce O2 to a current density of 1.5 mA.cm-2 on a carbon nanotube fiber, so that obtained only 0.3 mA.cm-2 using a carbon fiber "classic". Moreover, once changed, the nanotube fibers have been shown 10 times more stable than carbon fibers. These results clearly demonstrate the benefits of such electrodes:
- increase the specific surface of the electrode,
- increase the current density limit,
- improvement of electron transfer between enzyme and electrode,
- improving system stability.
These new electrodes are a major step for the realization of future devices such as sensors bioelectrochemical or stockpiles for food or medical sensor portable electrical appliances (communication, electronics).
© Nicolas Mano - CRPP
Figure 1.
Electroreduction of O2 on a carbon fiber (thin) and an electrode of carbon nanotube fibers (thick) modified by Bilirubin Oxidase and its redox polymer. 20 mM phosphate buffer, 0.14 M NaCl, pH 7.2, 37.5 ° C, 1 mV / s.
© S. Knight - CRPP
Figure 2.
Schematic representation of the reduction of O2 on a carbon fiber (left) and a carbon nanotube fiber (right)
(Green: Redox polymer; blue: enzyme).Reference
Feng Gao, Lucie Viry, Maryse Maugey, Philippe Poulin & Nicolas Mano
Engineering hybrid nanotube wires for high-power biofuel cells
Nature Communications, April 12 2010
Nature Communications, April 12 2010
Research contacts
Tel: 05 56 84 30 22
Philippe Poulin , Paul Pascal Research Centre, Bordeaux
Email: poulin@crpp-bordeaux.cnrs.fr
Tel: 05 56 84 30 28
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