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Institut für Angewandte Physik,
TU Wien, 1040 Wien, Austria
Central European Institute of Technology (CEITEC), Brno University of Technology, Brno, 612 00, Czechia
Faculty of Physics, Center for Computational Materials Science, University of Vienna, 1090 Wien, Austria
Dipartimento di Fisica e Astronomia, Università di Bologna, 40127 Bologna, Italy
Advanced Research Center for Nanolithography, 1098XG Amsterdam, Netherlands
The ability to coordinate multiple reactants at the same active site is important for the wide-spread applicability of single-atom catalysis. Model catalysts are ideal to investigate the link between active site geometry and reactant binding, because the structure of single-crystal surfaces can be precisely determined, the adsorbates imaged by scanning tunneling microscopy (STM), and direct comparisons made to density functional theory. In this study, we follow the evolution of Rh1 adatoms and minority Rh2 dimers on Fe3O4(001) during exposure to CO using time-lapse STM at room temperature. CO adsorption at Rh1 sites results exclusively in stable Rh1CO monocarbonyls, because the Rh atom adapts its coordination to create a stable pseudo-square planar environment. Rh1(CO)2 gem-dicarbonyl species are also observed, but these form exclusively through the breakup of Rh2 dimers via an unstable Rh2(CO)3 intermediate. Overall, our results illustrate how minority species invisible to area-averaging spectra can play an important role in catalytic systems, and show that the decomposition of dimers or small clusters can be an avenue to produce reactive, metastable configurations in single-atom catalysis.
Corresponding author: Gareth S. Parkinson (parkinson).
You can download a PDF file of this open-access article from Angewandte Chemie International Edition or from the IAP/TU Wien web server.
There is also a version in German: Angewandte Chemie 136 (2024) e202317347.