WW Colloquium: Prof. Dr. Patricia Kooyman – Transmission electron microscopy in catalysis research – from ex situ to operando

Prof. Dr. Patricia Kooyman
Catalysis Institute, University of Cape Town, Rondebosch, South Africa
Transmission electron microscopy in catalysis research – from ex situ to operando

TEM is traditionally a high vacuum (10-6 Torr) technique, which offers atomic resolution imaging of a whole range of materials. Although a lot of useful information can be obtained from ex situ imaging, many materials have a different (surface) structure at elevated temperature as opposed to room temperature, and in vacuum as opposed to gaseous environment. The specific gas present can even influence the structure of a material. This means that traditional TEM images are mostly obtained of materials that are NOT in the state in which they are used in practice. One important area of application is catalysis research.
The development of differentially pumped ETEM was a significant step in the direction of real in situ TEM, allowing gas pressures of up to 50 mbar and heating up to about 1000 °C.
We have developed a micro-electro-mechanical system (MEMS) nanoreactor to bridge the pressure gap. It confines a thin layer of gas (several microns) in a windowed cell, thus retaining atomic resolution at pressures exceeding 1 bar by limiting the path length of gas the electron have to traverse. The catalyst under study (or its precursor) can be loaded into the nanoractor prior to the experiments. Small electron-transparent windows provide both good transmission of the electron beam and stability against the pressure difference. Heating is possible up to about 1000 °C. New developments include incorporation of a light source to study photocatalytic reactions.

Bernhard-Ilschner-lecture hall (H14)
Martensstr. 5-7, Erlangen

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Meeting-ID: 633 2071 1359
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