| The ever increasing demand for energy has spurred research into alternatives to conventional batteries and engines. Fuel cells have shown promise due to their high energy density and efficiency. Acidic media is conventionally used due to high proton conductivity and rapid anode kinetics. In addition, acidic membranes such as Nafion have been well-developed relative to alkaline membranes. Alkaline fuel cells (AFCs) are promising power sources due to superior cathode kinetics as compared to acidic media and due to the improved stability of inexpensive non-noble metal catalysts. H2 fuel is conventionally used due to its fast oxidation kinetics, but alternate liquid or solid fuels (e.g., methanol, ethanol, NaBH4, ethylene glycol) are being studied to achieve higher energy density. Major limitations for fuel cells have included the high cost of Pt catalysts, low power density and efficiency for non-H 2 fuels (Chapter 1), and a lack of understanding of the complex processes inside operating fuel cells (Chapter 2). Testing each potential configuration in a membrane fuel cell has synthetic difficulties and can be costly; in addition, membrane fuel cells are largely limited to whole cell analytical information (e.g. polarization and power density curves).;We have previously used a microfluidic H2/O2 fuel cell as an analytical platform to determine the effects of carbonate formation in alkaline fuel cells. The microfluidic fuel cell has modular components that can easily be swapped to test electrodes, electrolyte, or other aspects of the fuel cell. A reference electrode placed at the outlet allows for individual electrode analysis, which is not normally possible in conventional membrane-based fuel cells. External control over the electrolyte is possible by flowing in fresh electrolyte using a syringe pump. Previously, we have used this cell to examine cathode catalysts, electrode degradation, and carbonate poisoning. In addition, we have developed an analytical method to better interpret microfluidic fuel cell results (Chapter 2).;Using the microfluidic H2/O2 fuel cell, the focus of this work is to provide insight and development in several areas:;•(Chapter 3) determines the effect of ethanol contamination under operational conditions in an alkaline fuel cell.;•(Chapter 4) examines the role of hydrophobicity and other anode parameters in alkaline media and describes improvements to electrode performance.;•(Chapter 5) shows analysis and development of a novel Cu-centered catalyst in acidic media and determines limiting factors for scaling catalysts from RDEs to fuel cells.;•(Chapter 6) chronicles the development of a laminar-flow fuel cell compatible with two gas streams and demonstrates applications for power generation and contaminant analysis.;•(Chapter 7) evaluates a Fe-N catalyst in acidic and alkaline media, both under normal conditions and in the presence of contaminants.;These results aid the development and understanding of fuel cell catalysis, as well as identification of key parameters determining the viability of fuel cell systems. |
