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A Spectroscopic Investigation of Photoelectrochemical Reactions at the Semiconductor - Electrolyte Interface for Artificial Photosynthesis

出版	University of California, Berkeley, 2016
URL	http://books.google.com.hk/books?id=kE4HtAEACAAJ&hl=&source=gbs_api

註釋The mechanism of water oxidation to molecular oxygen at the surface of strontium titanate, a representative transition-metal oxide photocatalyst, was investigated using ultrafast pump-probe spectroscopy and accompanying characterization methods. The dependence of the rate of initial charge transfer on applied potential was investigated with transient absorption spectroscopy, revealing a phenomenological transfer coefficient for this single step of the multi-step water oxidation reaction. Time resolved infrared spectroscopy provided the first direct evidence of the molecular character of the first intermediate to be a titanium-bound oxyl radical, and revealed interfacial Fano coupling between the electrolyte, surface species, and catalyst electronic continuum. Further work combining both transient absorption and time-resolved mid-infrared spectroscopy exposed a minimum of three distinct surface states at the strontium titanate surface, providing insight into the rich chemistry mediated at the catalyst surface. These results highlight the intricacies of charge transfer at the surface of these promising materials, provide insight into an important but difficult reaction necessary for any artificial photosynthetic system, and offer a generalizable paradigm for considering heterogeneous photochemistry. Finally, preliminary groundwork was done to uncover the mechanism of the carbon dioxide reduction half reaction in a novel inorganic-biological bacterial system with potential to produce green chemicals such as carbon-neutral liquid fuels.