Polyethylenimine Redox Polymers for Bioelectrocatalysis

University Of Oklahoma Norman Campus, Norman OK

Investigators

Abstract

0967988 Schmidtke Fuel cells convert chemical energy directly into electricity through an oxidation reaction at the anode and a reduction reaction at the cathode. In enzymatic biofuel cells, traditional fuel cell catalysts (e.g. Pt, Pd, Ru) are replaced by fuel oxidizing enzymes (e.g. Glucose Oxidase, Alcohol Dehydrogenase, Fructose Dehydrogenase) at the anode and oxygen reducing enzymes (e.g. Laccase, Bilirubin Oxidase) at the cathode. Currently the main limitations of enzymatic biofuel cells are low power output and limited lifetimes. Principal Investigators David Schmidtke and Daniel Glatzhofer at the University of Oklahoma, Norman Campus have hypothesized on the limiting factors. In enzymatic biofuel cells, the redox center of most enzymes is buried in the protein shell and electrically inaccessible. Thus most redox enzymes do not normally exchange electrons with an electrode. They propose to increase the power output of enzymatic biofuel cells by synthesizing redox polymers that increase the rate of electron transfer (i.e. current flow)between the redox enzymes and electrodes. These novel PEI-based redox polymers produce high currents by efficiently collecting and shuttling electrons between the enzyme¡¦s redox center and the electrode surface. These polymers contain metal species, ferrocene compounds, linked to the polymer. Tuning the system will require synthesis of polymers with different lengths of spacer arms. The PIs are targeting a 20-200 fold improvement in power output. Enzymatic biofuel cells will not solve the nation¡¦s energy needs. However, as the demand for portable energy increases, there develops a need for alternative renewable energy sources. Enzymatic biofuel cells are an attractive energy conversion technology because they operate at mild temperatures of20-40?aC and under neutral pH and consume substrates such as sugars that are readily available in biological systems. Because of their inherent selectivities, enzyme based anodes and cathodes can operate in the same compartment without separating membranes thereby reducing size and weight. They have potential applications for both in vivo (e.g. pacemakers, implantable sensors) and ex vivo (e.g. remote site sensing, mobile electronics) systems. The investigators intend to use their research as a vehicle to increase the attractiveness of the field to potential students. Their belief, based on studies, is that a student¡¦s attitude toward science and his achievement in science improves with hands-on experiences. To help increase the likelihood that students will continue their studies in science and engineering, proposed educational activities with research opportunities include Research Opportunities for Undergraduate students and Summer Research Internships for Underrepresented Groups, matched with Research Opportunities for Middle School Teachers.