Atomic-scale studies of catalysis
by spinel oxides
The spinel class of metal oxides hosts diverse materials, some of which make excellent catalysts. Fe3O4 is already the industrial catalyst for the high-temperature water-gas shift reaction (CO+H2O -> H2+CO2), but research is needed to identify the optimal replacement for the toxic Cr promoter/stabilizer. Ternary MeFe2O4 compounds (Me=Fe, Ni, Co, Mn) are active and stable for the electrochemical oxygen evolution reaction (OER). However, the structure of the active catalyst and the reaction mechanisms are unknown. While these reactions appear different, both clearly benefit from a combination of multivalent cations in the surface layers.
In this project, we will seek to learn why, using a combination of atomic-scale imaging, a host of spectroscopies, and theory. We will dope the Fe3O4(001) surface with 3d transition metals and investigate how the adsorption energies, XPS binding energies, and IRAS frequencies of H2O, CO, CO2, O2, and H2 change with sample composition all the way from isolated dopants to ternary thin films. We will use the data obtained in tightly-controlled UHV experiments to:
ii) Provide the benchmark data for experiments on nominally similar powder catalysts (P10 Föttinger).
iii) Support the development of theoretical modeling (P07 Franchini).
A joint postdoc (P04-P11) will facilitate the new collaboration with P11 Backus.
- Scanning Tunneling Microscopy (STM) (in UHV 4K – 300 K, electrochemical STM)
- Atomic Force Microscopy (AFM): UHV-based (q+ sensor) and in the ambient (cantilever-based)
- Low-Energy Electron Diffraction (LEED)
- Reflection High Energy Diffraction (RHEED)
- X-ray Photoelectron Spectroscopy (XPS)
- Ultraviolet Photoelectron Spectroscopy (UPS)
- Auger Electron Spectroscopy (AES)
- Low-energy He+ ion scattering (LEIS)
- Thermal Programmed Desorption Spectroscopy (TPD)
In: Electrochimica Acta, 389 , pp. 138638, 2021.
Unraveling CO adsorption on model single-atom catalysts Journal Article
In: Science, 371 (6527), pp. 375–379, 2021.
In: Physical Review Letters, 125 (20), pp. 206101, 2020.
In: Angewandte Chemie - International Edition, 59 (49), pp. 21904–21908, 2020.
In: Angewandte Chemie - International Edition, 58 (39), pp. 13961–13968, 2019.