Title : Electroenzymatic catalysis for electrical energy production
Abstract:
The need for clean methods of producing electricity have stimulated the emergence of new generation of fuel cells. A subcategory of fuel cells, biofuel cells, mainly rely on redox enzymes, which are very efficient and selective biocatalysts that can advantageously replace rare and expensive platinum-based catalysts in classic fuel cell devices. Enzymes provide exceptional specificities towards their substrates, thus enabling the assembly of both the anode and cathode electrodes of a biofuel cell without the need for membranes. These biodevices that convert chemical energy into electrical energy by electro-enzymatic reactions, have attracted considerable attention over the last decade. Recent advances in the design of bioelectrodes based on electrically wired enzymes onto carbon nanotube coatings will be reported. In particular, different strategies for achieving a controlled orientation of laccase or bilirubin oxidase on carbon nanotube-based electrodes for the direct dioxygen reduction will be presented. A new generation of flexible buckypaper electrodes was produced by using linear polynorbornene polymers containing multiple pyrene groups as crosslinker. In addition, the use of bifunctionalized polymers (pyrene and NHS groups) leads to robust buckypapers with the covalent binding of redox groups or enzymes. Moreover, buckypapers based on bilirubin oxidase and FAD-dependent glucose dehydrogenase, were developed for the direct electron transfer and the mediated electron transfer, respectively. The resulting EFC based on the O2/glucose system, provides the highest volumetric power reported until now, namely 24.07 mW cm-3. The design of hybrid biofuel cells will be also reported. In particular, cubic Pd nanoparticles were synthesized and evaluated for the catalytic oxygen reduction. These nanoparticles were employed for the development of an air-breathing cathode modified by multiwalled carbon nanotubes. The latter was combined with a phenanthrolinequinone/glucose dehydrogenase-based anode to form a complete glucose/O2 hybrid biofuel cell. Another hybrid system based on hydrogen/air biofuel cell integrating a bioinspired nickel catalyst and a bilirubin oxidase will be described. The biomimetic nickel bis-diphosphine complex immobilized on modified single-wall carbon nanotubes exhibits a reversible electrocatalytic activity for the H2/2H+ interconversion.
Biomimetic fuel cells involving non-covalently attached network of porphyrins to multi-walled carbon nanotubes will be also described. Pyrene-functionalized Rhodium deuteroporphyrin was used as an anode in the electrocatalytic oxidation of glucose and pyrene-functionalized tetracarboxyphenyl Cobalt porphyrin was used as a cathode in the electrocatalytic reduction of oxygen. The resulting glucose fuel cell led to a maximum power output of 0.9(± 0.10) mW cm-2. Finally, an innovative approach based on the electrical wiring of enzymes in solution by redox glyconanoparticles resulting from the self-assembly of bio-sourced block copolymers will be presented. We demonstrate the self-assembly, characterization and bioelectrocatalysis of redox-active cyclodextrin-coated nanoparticles. The nanoparticles with host-guest functionality are easy to assemble and permit entrapment of hydrophobic redox molecules in aqueous solution. The nanoparticles (diameter: 195 nm) were used as electron shuttles between electrode and bilirubin oxidase providing enhanced current densities for enzymatic O2 reduction.
