12 Scientific Article The Israel Chemist and Chemical Engineer Issue 8 · November 2021 · Kislev 5782 Charlotte Vogt received her PhDwith Greatest Distinction fromUtrecht University in the Netherlands in 2020, working with Professor Bert Weckhuysen. In 2021, she was listed on Forbes’ ‘30 under 30’ list and in the same year she started her own research group as Assistant Professor at the Technion Institute for Technology in Israel. Her group focuses on the development of novel tools for deep fundamental understanding of catalytic processes at work. Separating the “players” from the “spectators” in operando spectroscopy of catalysis Charlotte Vogt Schulich Faculty of Chemistry, Technion, Israel Institute of Technology, Technion City, Haifa 32000, Israel Email: [email protected] Abstract Surface processes at complex material interfaces are important for many different applications, most notably heterogeneous catalysis. Approximately 90% of chemical processes - and thus nearly all manmade things - include at least one catalytic step. Studying relevant surface processes allows us to rationally design new or better catalysts andmaterials but it is difficult to do so under relevant conditions of temperature, pressure, andmaterial complexity. In this article, I discuss an experimental approach borrowed from lock-in amplifiers, equipment often found in physics laboratories, which can overcome many of these challenges. In this way, we can study details of catalytic reactions under highly relevant conditions with the aim to generate the next generation of fundamental insights into surface processes. 1. Studying catalysts at work 1.1 The complexity of catalyst systems A surface or an interface defines a boundary between a material and its surrounding environment. At an atomic level, surface atoms have a different chemical environment from those in the bulk of the material; they have fewer nearest neighbors. As such, surface atoms exhibit higher chemical reactivity, and this general property makes them very useful in a large variety of chemical and biological processes. To increase the available surface per unit weight of material, it is common practice to finely divide the material whose surface properties are desired, thereby forming e.g., nanoparticles which are often supported on high-surface area (metal oxide) supports. Another commonly used form of (high-surface area) catalysts are zeolites, which act as solid Brønsted acids. Supported nanoparticular catalysts and zeolites by far make up the largest fraction (in terms of catalyst weight, product weight, and also economic value) of processes that are applied industrially. Such materials are used and studied throughout industry and academia, for example in catalysis, but also in materials science, across energy storage applications, and so forth, due to their high chemical reactivity and stability [1]. During catalytic processes, molecular adsorbates at the surface affect the surface, geometric, and electronic structure of the catalysts, particularly so at the high temperatures and pressures which are often relevant to actual applications (for example, the Haber-Bosch process occurs above 350 °C and at pressures of over 200-300 bar) [2]. Our current understanding of such fundamental changes to relevant catalysts at operating temperatures and pressures is lacking; there are so-called temperature-, pressure- and material complexity gaps [3]. One of the reasons that so much is still unknown is that it is inherently difficult to study processes at surfaces under relevant conditions. For a catalytic system that is in interaction https://doi.org/10.51167/ice00009
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