The third main focus of the Minteer Group is high power density and long lifetime biofuel cells. A biofuel cell is a type of battery that can be recharged with the addition of more fuel and utilizes enzymes as biocatalysts in order to convert chemical reactions to electrical energy. Our research group has developed a powerful technique to immobilize enzymes at the electrode surface. This technique has helped to stabilize enzymes for increased periods time (months instead of days) by protecting fragile enzymes in tiny pore-like structures resulting in increased power and lifetime of the biofuel cell. In addition, with this technique a wide variety of fuels can be utilized including carbohydrates, fatty acids, and alcohols.
Chitosan modified electrodes for ethanol/oxygen biofuel cells. Duma, Rodica; Minteer, Shelley D.. Department of Chemistry, Saint Louis University, St. Louis, MO, USA. Abstracts of Papers, 233rd ACS National Meeting, Chicago, IL, United States, March 25-29, 2007 (2007), PMSE-340.
Abstract
This work details the use of hydrophobically modified chitosan for the development of bilirubin oxidase biocathodes for membraneless ethanol/oxygen biofuel cells. In the described configuration, both the anode and the cathode electrodes in the biofuel cell employ biol. catalysts (enzymes) instead of traditional fuel cell catalysts (heavy metals). This enzymic biofuel cell employs alc. dehydrogenase to oxidize ethanol at the anode and bilirubin oxidase to reduce oxygen at the cathode. These ethanol/oxygen biofuel cells have an active lifetime of about 18 days and shows power densities of up to 1.67mW/cm2. The biocathodes used in this work are unique in that the enzyme bilirubin oxidase is immobilized within a modified Nafion DE520 polymer or a modified Chitosan-Bu polymer that acts both to entrap and stabilize the enzyme. These biocathodes are fuel tolerant, which leads to a fuel cell that employs both renewable catalysts and fuel, but does not require a separator membrane to sep. anolyte from catholyte.