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Hi, The Thursday CORE - CM ``pizza" seminar this week *April 18: Tom Hamann * /Chemistry, Michigan State University / "Photoelectrochemical Investigation of Water Splitting with Hematite Thin Film Electrodes" abstract is below Pizza and cookies available at 11:45 Phil +++++++++++++++++++++++++++++++++ Hematite has long been considered a potential candidate for photocatalytic water splitting because of its favourable valence band edge, reasonably low band gap, high stability and low cost. Unfortunately, only very poor conversion efficiencies have been achieved, which is generally attributed to a short minority carrier collection length. In principle, the short collection length can be overcome through nanostructuring the electrode. Thin films represent ideal model systems of nanostructured electrodes which allow for detailed mechanistic investigations. We utilize atomic layer deposition (ALD) to make conformal thin film hematite electrodes with controllable thickness for this purpose. Films less than 20 nm thick, however, are plagued by a dead layer near the substrate contact. We found that the dead layer can be alleviated by the incorporation of dopant atoms in the hematite film, which lead to dramatically improved water oxidation efficiencies. A series of electrochemical, photoelectrochemical and impedance spectroscopy measurements were employed to elucidate the cause of the improved photoactivity of the doped hematite thin films. This performance enhancement was determined to be a combination of improved bulk properties (hole collection length) and surface properties (water oxidation efficiency). The non-ideal water oxidation efficiency constrains the overall water splitting efficiency. Recent results of adding catalysts to the hematite surface in order to improve the water oxidation efficiency will also be presented.