Local Structure and Coordination Define Adsorption in a Model Ir<sub>1</sub>/Fe<sub>3</sub>O<sub>4</sub> Single-Atom Catalyst

Author(s)
Zdenek Jakub, Jan Hulva, Matthias Meier, Roland Bliem, Florian Kraushofer, Martin Setvin, Michael Schmid, Ulrike Diebold, Cesare Franchini, Gareth S. Parkinson
Abstract

Single-atom catalysts (SACs) bridge homo- and heterogeneous catalysis because the active site is a metal atom coordinated to surface ligands. The local binding environment of the atom should thus strongly influence how reactants adsorb. Now, atomically resolved scanning-probe microscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption, and DFT are used to study how CO binds at different Ir-1 sites on a precisely defined Fe3O4(001) support. The two- and five-fold-coordinated Ir adatoms bind CO more strongly than metallic Ir, and adopt structures consistent with square-planar Ir-I and octahedral Ir-III complexes, respectively. Ir incorporates into the subsurface already at 450 K, becoming inactive for adsorption. Above 900 K, the Ir adatoms agglomerate to form nanoparticles encapsulated by iron oxide. These results demonstrate the link between SAC systems and coordination complexes, and that incorporation into the support is an important deactivation mechanism.

Organisation(s)
Computational Materials Physics
External organisation(s)
Technische Universität Wien, Adv Res Ctr Nanolithog ARCNL, Center for Computational Materials Science
Journal
Angewandte Chemie (International Edition)
Volume
58
Pages
13961-13968
No. of pages
8
ISSN
1433-7851
DOI
https://doi.org/10.1002/anie.201907536
Publication date
09-2019
Peer reviewed
Yes
Austrian Fields of Science 2012
Materials physics, Surface physics
Keywords
Portal url
https://ucris.univie.ac.at/portal/en/publications/local-structure-and-coordination-define-adsorption-in-a-model-ir1fe3o4-singleatom-catalyst(5e654884-e7b7-4ede-9b84-ce891091b589).html