Title: Biofuel Cell Gas-Diffusion Cathodes based on Multiwalled Carbon Nanotube Matrix
Authors: S. Omar Garcia, Claudia Narváez Villarrubia, Akinbayowa Falase, and Plamen Atanassov
Affiliations: 1Center for Emerging Energy Technologies, University of New Mexico, 2Center for Biomedical Engineering, University of New Mexico, 3Department of Chemical and Nuclear Engineering, University of New Mexico
Abstract: This design is of a carbon nano-structured cathode for an enzymatic biofuel cell which uses biocatalysts to convert energy stored in organic compounds, such as sugars and alcohols, into electricity. Enzymatic biofuel cells use enzymes to catalyze the oxidation of fuel at the anode and reduction of oxygen at the cathode. The cathode reduces oxygen to water (via direct electron transfer which is desired for enhanced catalytic performance) through the immobilization of bilirubin oxidase on carbon nano-tube (CNT) modified Toray paper. The design of a viable air-breathing cathode must accomplish two requirements: 1) it must have a porous hydrophobic layer that allows the flow of oxygen to feed the catalytic layer, and 2) a porous thin catalytic layer that enhances the enzyme-air-electrolytic solution interaction.
The objective of this research is to design a stable air breathing-enzymatic layer on the surface of a teflonized carbon fiber paper called Toray paper. The cathode is optimized by utilizing a dual layered electrode consisting of two carbon composite materials. One layer has hydrophobic and porous properties to allow oxygen transport (XC35 carbon powder); the corresponding hydrophilic layer is thin and has a high surface area for enzyme loading and stability (CNT modified Toray paper by chemical vapor deposition). This combination allows efficient transport of oxygen giving the enzyme more surface area to be immobilized on. Evidence of Toray paper modification and enzyme entrapment are supported by SEM imaging and electrochemical tests. An efficient biofuel cell can be used in portable, small electrical devices.