Studies On Enzymatic Biofuel Cells

Because of the increasingly serious energy problems, it is more and moreimportant to look for a green and renewable energy. The development of enzymaticbiofuel cells has attracted the considerable attention for society because of theirextensive fuel sources, mild reaction conditions and good biocompatibility.Enzymatic biofuel cells belong to a special kind of fuel cells, which use enzymebiocatalysts to instead of the traditional metal catalysts. Enzyme biocatalysts areemployed to oxidate the fuels （such as glucose, alcohol etc） for the conversion ofchemical energy into electrical energy. Enzymatic biofuel cells can be used asembedded power, on the other hand it makes great contribution to biomass energyusing. But in the current researches its development has been restricted by the lowoutput power density. And it is very important to solve the problem that we havemet in developing enzymatic biofuel cells. Electrode materials often decides theperformance of enzymatic biofuel cells. How to reach a maximum catalytic andoxidation of the substrates is also the key.Based on this situation, we constructed a multienzyme catalytic system whichcan oxidize alcohol to CO₂through a multi-step oxidation. On the other hand, weprepared the carbon nanodots as the electrode material and studied itselectrochemical performance. Specific content as follows：1. We built a biofuel cells anode which is multienzyme-poly methylene blue（polyMB） and multiwalled carbon nanotubes （MWCNTs） modified electrode. In this system we used alcohol dehydrogenase （ADH）, aldehyde dehydrogenase（ALDH） and formate dehydrogenase （FDH） as the anodic biocatalysts. First tooxidize alcohol to ethanal then to oxidize to acetic acid last to oxidize to CO², Thegeneration of H⁺by each step combined with NAD⁺to get NADH and the polyMBcontinue to oxidized NADH to NAD⁺. By comparing the experimental results, thecurrents of oxidizing alcohol by multienzyme catalyst is higher than single enzymecatalyst and have greater output power density.2. We have synthesized a new kind of material carbon nanodots （CNDs） aselectrode materials and built a bilirubin oxidase modified glassy carbon electrodeswhich containing CNDs as the biofuel cells cathode. The modified electrodeexhibits a good eletrocatalytic activity to the reduction of oxygen.