John Kitchin, Associate Professor of Chemical Engineering, Carnegie Mellon University
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Electrochemical water splitting may be in integral part of future energy storage strategies by enabling energy storage in chemical bonds. One of the primary sources of inefficiency in the water splitting reaction is the oxygen evolution reaction, which has high reaction barriers that require additional applied electric potential to drive the reactions at practical rates. The most active electrode materials in acid electrolytes include ruthenium and iridium oxides, which are expensive but necessary for stability. In alkaline environments, many base metal oxides become stable, although they are still less active than Ru and Ir oxides. It has been known that small amounts of Fe can promote the electrochemical activity of nickel oxides, making it almost as active as cobalt oxide. We have investigated the mechanisms behind the promotion using in situ Raman and synchrotron spectroscopies as well as ex situ characterization techniques. Interestingly, we found the electrode changes under oxygen evolution conditions, turning from an oxide to an oxyhydroxide phase. Furthermore, the composition of the electrolyte has a significant effect on the oxygen evolution activity. We will discuss these results and their implications in finding better oxygen evolution electrocatalysts.
This talk was given as part of the MITEI Seminar Series, made possible with the support of IHS-CERA.