Membrane/mediator-free rechargeable enzymatic biofuel cell utilizing graphene/single-wall carbon nanotube cogel electrodes.

Enzymatic biofuel cells (EBFCs) utilize enzymes to convert chemical energy present in renewable biofuels into electrical energy and have shown much promise in the continuous powering of implantable devices. Currently, however, EBFCs are greatly limited in terms of power and operational stability with a majority of reported improvements requiring the inclusion of potentially toxic and unstable electron transfer mediators or multicompartment systems separated by a semipermeable membrane resulting in complicated setups. We report on the development of a simple, membrane/mediator-free EBFC utilizing novel electrodes of graphene and single-wall carbon nanotube cogel. These cogel electrodes had large surface area (∼800 m2 g–1) that enabled high enzyme loading, large porosity for unhindered glucose transport and moderate electrical conductivity (∼0.2 S cm–1) for efficient charge collection. Glucose oxidase and bilirubin oxidase were physically adsorbed onto these electrodes to form anodes and cathodes, respectiv...