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Title:Electrochemistry of formic acid and carbon dioxide on metal electrodes with applications to fuel cells and carbon dioxide conversion devices
Author(s):Haan, John L.
Director of Research:Masel, Richard I.
Doctoral Committee Chair(s):Masel, Richard I.
Doctoral Committee Member(s):Wieckowski, Andrzej; Gewirth, Andrew A.; Scheeline, Alexander
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):formic acid fuel cell
carbon dioxide reduction
Abstract:There is a growing awareness of the need for basic and applied energy research due to the environmental impact of energy use and limitations in the supply of energy sources. In this work, electrochemical research is reported for fuel cells and carbon dioxide reduction, with the aim of reducing the environmental footprint of global energy use. In studies of the formic acid fuel cell, it is reported here that an increase in the formic acid fuel pH increases the rate of formic acid oxidation on palladium and platinum. It is also shown that an increase in fuel pH decreases the potential at which the catalyst poison is removed from the electrode surface. This poison is detrimental to fuel cell operation. This work reports the first such studies in an electrochemical cell on high surface area platinum and palladium nanoparticles. New catalyst formulations were developed via electrochemical surface modification in attempt to eliminate the catalyst poisoning and improve performance of the formic acid fuel cell. Electrochemical studies showed substantial improvement to the rate of formic acid oxidation by a combination of high surface area palladium with tin, antimony, or lead, due to steric and electronic effects. A membrane electrode assembly was developed and reported here that enables fuel cell testing of such electrochemically modified catalysts. Tests in an operating fuel cell demonstrated less performance gains compared with the electrochemical cell, although some gains were shown. Finally, the reduction of carbon dioxide in the ionic liquid, EMIM BF4, was shown to occur at a more positive potential that in previous aprotic solvents such as acetonitrile. The conversion of carbon dioxide to its charged intermediate was shown to occur as the rate limiting step in the complete conversion of carbon dioxide to adsorbed carbon monoxide. This work is part of the initial stages of an effort to convert carbon dioxide to a usable fuel such as formic acid or some other larger hydrocarbon fuel.
Issue Date:2010-08-20
Rights Information:Copyright 2010 John L. Haan
Date Available in IDEALS:2010-08-20
Date Deposited:2010-08

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