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Local Structure and Coordination Define Adsorption in a Model Ir 1 /Fe 3 O 4 Single‐Atom Catalyst
Author(s) -
Jakub Zdenek,
Hulva Jan,
Meier Matthias,
Bliem Roland,
Kraushofer Florian,
Setvin Martin,
Schmid Michael,
Diebold Ulrike,
Franchini Cesare,
Parkinson Gareth S.
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201907536
Subject(s) - catalysis , adsorption , atom (system on chip) , x ray photoelectron spectroscopy , octahedron , chemistry , crystallography , metal , infrared spectroscopy , scanning tunneling microscope , coordination number , spectroscopy , desorption , materials science , nanotechnology , crystal structure , chemical engineering , ion , physics , organic chemistry , quantum mechanics , computer science , engineering , embedded system
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 Fe 3 O 4 (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.