Les biopiles enzymatiques constituent une alternative intéressante de production d'électricité renouvelable. On s'est intéressé dans ce travail au compartiment cathodique d'une biopile utilisant la laccase, une oxydase multi-cuivres, comme biocatalyseur pour la réduction de l'oxygène (ORR) par transfert direct des électrons. Plusieurs stratégies ont été mises en œuvre afin d'optimiser la cinétique de l'ORR sur électrode de graphite. Une des stratégies a consisté à déposer un film mince de nitrure de carbone amorphe (a-CNx) sur le graphite. La présence de groupements amines de surface a ensuite permis le greffage covalent de la laccase. Des groupements carboxyliques peuvent également être introduits par un traitement électrochimique. En alliant plusieurs techniques de caractérisation, notamment des mesures d'impédance, on a démontré que notre système se comporte comme un réseau de microélectrodes. Pour ce type d'électrode on a mesuré une densité de courant maximale de -44,6 µA/cm2. Dans une autre stratégie, la surface du graphite a été nanostructurée par formation de nanowalls de carbone (CNWs) par dépôt chimique en phase vapeur assisté par plasma. On a optimisé les conditions du traitement ultérieur de fonctionnalisation de la surface par APPJ en ayant recours à des plans d'expériences, ce qui a permis d'atteindre des densités de courants de l'ordre de -1 mA/cm2. On a également étudié l'orientation et la cinétique de greffage de l'enzyme sur une surface d'or en utilisant la technique PM-IRRAS. / Enzymatic biofuel cells are an attractive alternative for renewable electricity generation. In this work, we are focusing on the cathodic compartment of a biofuel cell using laccase, a multi-copper oxidase, as biocatalysts for the oxygen reduction reaction (ORR) by direct electron transfer of electrons. Several strategies have been used to optimize the kinetic of ORR on graphite electrode. One strategy was to deposit thin film of amorphous carbon nitride (a-CNx) on graphite. The presence of surface amine groups then allowed the covalent grafting of the laccase. Carboxylic groups can also be produced by an electrochemical treatment. By combining several characterisation techniques, especially impedance measurements, we have demonstrated that our system behaves like microelectrodes network. For this type of electrode, we have measured a maximal current density equal to -44,6 µA/cm2. In another strategy, the surface of graphite was nanostructured by forming carbon nanowalls (CNWs) using the plasma-enhanced chemical vapour deposition technique in a CO/H2 microwave discharge. We have optimized then the APPJ functionalization conditions using experiments design. We reached current densities of the order of -1 mA/cm2. We have also studied the orientation and the kinetic of enzyme immobilisation on gold surface using PM-IRRAS technique.

Technologies laser pour l’élaboration de matériaux carbonés pour microsystèmes analytiques environnementaux. Pas de résumé en français fourni / Amorphous carbon nitride (a-CzN) material has attractor much attention in research and development. Recently, it has become a more promising electrode material than conventional carbon based electrodes in electrochemical and biosensor applications. Nitrogen containing amorphous carbon (a-C:N) thin films have been synthesized by femtosecond pulsed laser deposition (fs-PLD) coupled with plasma assistance through Direct Current (DC) bias power supply. During the deposition process, various nitrogen pressures (0 to 50 Pa) and DC bias (0 to -350 V) were used in order to explore a wide range of nitrogen content into the film. The structure and chemical composition of the films have been studied by using Multi-wavelength (MW) Roman spectroscopy, electron energy-loss spectroscopy (EELS), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTBM). The surface morphology has been studied by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Increasing the nitrogen pressure or adding a DC bias induced an increase of the N content, up to 28 at.%. Nitrogen content increase induces a higher sp2 character of the film. However DC bias has been found to increase the film structmal disorder, which was detrimental to the electrochemical properties. Indeed the electrochemical measurern-ts, investigated by cyclic voltammetry (CV), demonstrated that the a-CzNfilms show better electron transfer kinetics, reversibility and excellent reproducibility than the pure a-C films. Electrochemical grafting from diazoniurn salts was successfully achieved on this film, with a surface coverage of covalently bonded molecules close to the dense packed monolayer of ferrocene