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D2.06 - Atomic Level In-Situ Characterization of Metal/TiO2 Photocatalysts Under Light Irradiation in Water Vapor 
April 22, 2014   4:00pm - 4:15pm

TiO2 is a semiconducting oxide used as a UV-light photocatalyst with potential applications to degradation of organics and solar fuel generation. The photocatalytic activity can be significantly enhanced via the deposition of metal particles onto the oxide surface. Photogenerated electrons are transferred to the metal while the holes remain in the TiO2 valence band thus suppressing electron-hole pair recombination. It is now recognized that atomic level in situ observations of catalytic nanomaterials are critical for understanding structure-reactivity relations because the active form of the material may exist only under reaction conditions. We have undertaken a series of in situ TEM experiments to develop a fundamental understanding of metal particle/TiO2 structure changes in reaction conditions. Such an analysis is performed under in situ conditions in the presence of light and reactants in an environmental transmission electron microscope (ETEM).[1] Here we employ a modified ETEM with a broadband light source to study the behavior of metal particles on TiO2 semiconductor surfaces under photoreaction conditions. Insights from these experiments can help in the design of photocatalysts with better performance and stability. Preliminary experiments showed that the surfaces of anatase nano particles becomes disordered in water vapor under light exposure in the electron microscopes. [2] In this study we investigate the changes that occur in a variety of supported metal systems including Pt/TiO2, one of the most efficient metal/TiO2. Pt coupled anatase nanoparticles were prepared by photodeposition. Light induced surface and interface changes will be presented. Catalytical properties before and after structure change are tested by measuring H2 production under Xenon lamp using gas chromatography. Structure-reactivity relationships will also be discussed for the Pt system and a number of transition metals. References: [1]. Miller, B.K.; Crozier, P.A. Microscopy and Microanalysis., 2013 DOI: 10.1017/S1431927612014122. [2]. Zhang, L.; Miller, B.K.; Crozier, P.A. Nanoletter 2013, DOI: 10.1021/nl304333h

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Keynote Address
Panel Discussion - Different Approaches to Commercializing Materials Research
Business Challenges to Starting a Materials-Based Company
Fred Kavli Distinguished Lectureship in Nanoscience
Application of In-situ X-ray Absorption, Emission and Powder Diffraction Studies in Nanomaterials Research - From the Design of an In-situ Experiment to Data Analysis