Document Type

Dissertation

Date of Award

8-30-2019

Degree Name

Doctor of Philosophy in Materials Science and Engineering - (Ph.D.)

Department

Committee for the Interdisciplinary Program in Materials Science and Engineering

First Advisor

Zafar Iqbal

Second Advisor

N. M. Ravindra

Third Advisor

Andrei Sirenko

Fourth Advisor

Kamalesh K. Sirkar

Fifth Advisor

Michael Jaffe

Abstract

Enzymatic biofuel cells (EBFCs) convert the chemical energy of biofuels, such as glucose and methanol, into electrical energy by employing enzymes as catalysts. In contrast to conventional fuel cells, EBFCs have a simple membrane-free fuel cell design due to the high catalytic specificity of the enzymes, but the power densities obtained are lower. Although the primary goal of research on EBFCs has been to develop a sustainable power source that can be directly implanted in the human body to power bio-devices, other applications such as the use of a flexible film or fuel cell patch as a wearable power source and sensor, are emerging. The power density and lifetimes of early EBFCs were not promising due to the difficulty of transporting electrons from reactive sites to the electrodes and the tendency of enzymes to migrate away from the electrodes. In recent years, direct electron transport via highly conducting functionalized multiwall carbon nanotubes has been demonstrated to be an effective solution. Further improvements can be made with enzyme immobilization during the procedure of bio-electrode fabrication.

This doctoral dissertation focuses on current problems of EBFCs involving immobilization of enzymes, and optimization of the performance of the cells. The technique of immobilization of enzymes, used in this dissertation, is hydraulic pressure to stabilize the enzymes on the electrodes. A novel design of EBFC in sandwich geometry with multiple configuration has been proposed, fabricated and tested. The performance tests of the samples have been conducted and presented by analyzing the polarization curves and power density versus time. Comparisons have been made to find the integrity/best performance of different configurations. The utility of the hybrid patch configuration and multiple units in series as a stack have been examined in accord with the protocol. A significant increase in power density has been observed for the hybrid EBFC patch units in series. The potential for commercialization and mass production of EBFC applications has been discussed. The preliminary results of the investigation of biofuel cell mechanisms by Surface-Enhancement Raman Spectroscopy (SERS) measurements is presented in the Appendix. With the combination of the usage of both Field Emission SEM and SERS, evidence of the existence of hydrogen peroxide can be verified. H2O2 plays an important role in the loss of power in EBFC samples.

The research in this dissertation will shed important light on the development of EBFC research and pave the way for viable commercialization applications.

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