Development of biomimetic systems for biofuel cell applications

Biomimics have been developed and characterized in order to further the understanding and the technology of bioelectrocatalysis. Glycerol, which is a natural product and also a byproduct of biodiesel production, has had limited success as a fuel as a result of its poor catalytic oxidation on traditional precious metals. However, since glycerol is a natural compound that has a natural metabolic pathway in living organisms, it remains a possibility to be efficiently oxidized to carbon dioxide by using biological catalysts. To do this a non-natural metabolic pathway was developed that uses a three enzyme cascade that had low substrate specificity and good direct electron transfer to carbon electrode materials. This allows glycerol and other similar compounds to be completely oxidized without the complexity of a natural pathway which would require many more steps.;Another method of accomplishing complete oxidation is using the organelle responsible for cellular energy generation, the mitochondria. Since the mitochondria already contain all of the necessary enzymes, cofactors, and pathways for complete oxidation of pyruvate and fatty acids, it is an ideal package for energy conversion. Mitochondrial bioanodes were developed and characterized for energy conversion of pyruvate and fatty acids in a biofuel cell system. In this study, the immobilized mitochondria were shown to be intact and viable by traditional viability assays, and the electron transport mechanism to the carbon electrode was probed.;In an effort to develop a totally synthetic, but biologically inspired catalyst for oxygen reduction, phthalocyanine doped carbon nanotubes were synthesized and characterized. This included development of a low temperature solvothermal synthesis of multiwalled carbon nanotubes by the reduction of carbon tetrachloride with iron metal powder in supercritical hexane. Then, using the same synthesis, perchlorinated phthalocyanine was added to the reaction so that the phthalocyanine is incorporated into the growing graphitic sheets of carbon. This yielded carbon nanotubes that contained catalytic sites where a chelated metal atom demonstrated similar catalysis as seen in biological catalysts, such as cytochrome c, but was designed for optimal operation in a fuel cell instead of a cellular environment.