Enzymatic biocatalysis (biofuel cells)
Fuel cells using enzymes and biofilms as catalysts

Numerous research teams are working on enzyme fuel cells, most often involving enzymes that oxidize the enzyme substrate used as fuel in the anode compartment and reduce oxygen in the cathode compartment. One of the key issues is how to attach the enzymes to the electrodes (entrapment in a conductive polymer matrix, covalent bonding with the enzyme's active site incorporating a mediator compound, layer-by-layer adsorption, etc.).

Different classes of oxidoreductases are used, such as oxidases or hydrogenases for oxidation, or laccases and peroxidases for reduction. They require the use of molecular tools to establish efficient electron transfer between the enzymes' active sites and the electrodes. These techniques are generally relatively sophisticated, difficult to implement and therefore costly, especially for large electrode surfaces. What's...