Characterizing the interaction of aqueous species with an amorphous surface is an extremely challenging task with important impact on the synthesis of many materials, including catalysts. We have been studying isolated cationic metals such as Zn2+, Fe2+, Co2+ etc. as highly stable and selective catalysts for alkane dehydrogenation. Most of our structural characterizations of silica-ion catalysts are done using bulk techniques after the material has been prepared or under catalytic conditions, even though the solution/surface interface is where the initial catalyst precursor/surface complex is prepared. We have created a molecular film of polymerized silica at the air-water interface and demonstrated the selective binding of Zn2+ ions using surface synchrotron X-ray scattering. Specular X-ray reflectivity demonstrates the location where the Zn2+ ions bind and grazing incidence X-ray diffraction measures the average order of the surface crystals before and after zinc binding. This technique enables the direct observation of ions associating with an amorphous surface, the structural changes that accompany ion binding, and will be broadly applicable to the study of catalyst synthesis in a variety of solvents.

Novel platform for studying catalyst precursors and synthesis on amorphous supports

251st National Meeting (2016)

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