Dresden 2020 – wissenschaftliches Programm
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SYED: Symposium Electron-driven processes: Atomic-scale insights from theory and experiment
SYED 1: Symposium Electron-driven processes
SYED 1.5: Hauptvortrag
Donnerstag, 19. März 2020, 11:45–12:15, HSZ 01
Single-Atom Catalysis (SAC): How Structure Influences Reactivity — •Gareth Parkinson — TU Wien, Vienna, Austria
The field of "single-atom" catalysis emerged as the ultimate limit of attempts to minimize the amount of precious metal used in heterogeneous catalysis. There are many reports of active catalysts for important heterogeneous, electrochemical and photoctalystic reactions, but it has become clear that metal adatoms behave very differently to supported nano-particles. This is because they form chemical bonds with the support and are often charged. Thus, SAC systems resemble coordination complexes used in homogeneous catalysis, and there is growing excitement that SAC could achieve similar levels of selectivity, and even "hetero-genize" problematic reactions currently performed in solution. Homogeneous catalysts are designed for purpose based on well-understood structure-function relation-ships, while in SAC, the complexity of real systems means that the structure of the active site is difficult to determine, never mind design. I will describe how we are using Fe3O4(001) as a precisely-defined model support to unravel fundamental mechanisms in SAC. First, I will describe systematic studies of CO adsorption across several metals (Cu, Ag, Au, Ni, Pt, Ir, Rh) and show that adsorbate-induced structural changes affect the stability of the catalyst and the desorption energy. Then I will describe how the local structure of Ir1/ and Rh1/Fe3O4(001) SACs change with preparation, and how CO adsorption stabilizes the system through square-planar and octahedral binding environments reminiscent of Ir1 and Rh1 based metalorganic complexes.