Digging its own site: Linear coordination stabilizes a Pt₁/Fe₂O₃ single-atom catalyst

A. Rafsanjani-Abbasi, F. Buchner, F. J. Lewis, L. Puntscher, F. Kraushofer, P. Sombut, M. Eder, J. Pavelec, E. Rheinfrank, G. Franceschi, V. Birschitzky, M. Riva, C. Franchini, M. Schmid, U. Diebold, M. Meier, G. K. H. Madsen, G. S. Parkinson

Institut für Angewandte Physik, TU Wien, 1040 Wien, Austria
Institute of Materials Chemistry, TU Wien, 1060 Wien, Austria
Faculty of Physics and Center for Computational Materials Science, University of Vienna, 1090 Wien, Austria
Dipartimento di Fisica e Astronomia, Università di Bologna, 40126 Bologna, Italy

ACS Nano 18 (2024) 26920-26927

Determining the local coordination of the active site is a prerequisite for the reliable modeling of single-atom catalysts (SACs). Obtaining such information is difficult on powder-based systems and much emphasis is placed on density functional theory computations based on idealized low-index surfaces of the support. In this work, we investigate how Pt atoms bind to the (1 -1 0 2) facet of α-Fe₂O₃; a common support material in SACs. Using a combination of scanning tunneling microscopy, X-ray photoelectron spectroscopy, and an extensive computational evolutionary search, we find that Pt atoms significantly reconfigure the support lattice to facilitate a pseudolinear coordination to surface oxygen atoms. Despite breaking three surface Fe-O bonds, this geometry is favored by 0.84 eV over the best configuration involving an unperturbed support. We suggest that the linear O-Pt-O configuration is common in reactive Pt-based SAC systems because it balances thermal stability with the ability to adsorb reactants from the gas phase. Moreover, we conclude that extensive structural searches are necessary to determine realistic active site geometries in single-atom catalysis.

Corresponding author: Gareth S. Parkinson (parkinson).

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