Sheet-shaped biofuel cell constructed from enzyme-modified nanoengineered carbon fabric

A strip of carbon fabric (CF) electrode modified with multiwalled carbon nanotubes and subsequently fructose dehydrogenase (FDH) showed an oxidation current density of ∼11 mA cm ^-2 in stirred 200 mM fructose solution. Obtaining a sufficient dispersion of the nanotubes during its modification was found to be critical to ensure such a performance of the FDH anode. For use with this anode, a CF strip modified with ketjenblack (KB) and bilirubin oxidase (BOD) served as a gas-diffusion cathode for the reduction of O ₂ from air at a current density of ∼2 mA cm ^-2. The FDH-modified CF strip and the BOD-modified CF strip were stacked with an agarose film that retained an electrolyte solution and fuel (fructose) to construct a totally flexible sheet-shaped biofuel cell. This assembly allowed bending of 44°without affecting the maximum output power density, 550 μW cm ^-2 obtained at 0.4 V.