The development of better energy conversion and storage devices, such as fuel cells and batteries, is crucial for reduction of our global carbon footprint and improving the quality of the air we breathe. However, both of these technologies face important challenges. The development of lower cost and better electrode materials, which are more durable and allow more control over the electrochemical reactions occurring at the electrode/electrolyte interface, is perhaps most important for meeting these challenges. Hence, full characterization of the electrochemical processes that occur at the electrodes is vital for intelligent design of more energy efficient electrodes.
X-ray absorption spectroscopy (XAS) is a short-range order, element specific technique that can be utilized to probe the processes occurring at operating electrode surfaces, as well for studying the amorphous materials and nano-particles making up the electrodes. It has been increasingly used in recent years to study fuel cell catalysts through application of the Δ&mgr; XANES technique, in combination with the more traditional X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) techniques. The Δ&mgr; XANES data analysis technique, previously developed and applied to heterogeneous catalysts and fuel cell electrocatalysts by the GWU group, was extended in this work to provide for the first time space resolved adsorbate coverages on both electrodes of a direct methanol fuel cell. Even more importantly, the Δ&mgr; technique was applied for the first time to battery relevant materials, where bulk properties such as the oxidation state and local geometry of a cathode are followed.
|Advisor:||Ramaker, David E., Licht, Stuart|
|Commitee:||Chen, Hanning, Mansour, Azzam, Massiah, Michael, Vertes, Akos|
|School:||The George Washington University|
|School Location:||United States -- District of Columbia|
|Source:||DAI-B 74/08(E), Dissertation Abstracts International|
|Subjects:||Alternative Energy, Analytical chemistry, Physical chemistry|
|Keywords:||Adsorption, Battery, Energy storage, Fuel cells, Renewable energy, Super iron, X-ray absorption spectroscopy|
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