Digging Its Own\nSite: Linear Coordination Stabilizes\na Pt<sub>1</sub>/Fe<sub>2</sub>O<sub>3</sub> Single-Atom Catalyst

Determining the local coordination of the active site\nis a prerequisite\nfor the reliable modeling of single-atom catalysts (SACs). Obtaining\nsuch information is difficult on powder-based systems and much emphasis\nis placed on density functional theory computations based on idealized\nlow-index surfaces of the support. In this work, we investigate how\nPt atoms bind to the (11̅02) facet of α-Fe<sub>2</sub>O<sub>3</sub>; a common support material in SACs. Using a combination\nof scanning tunneling microscopy, X-ray photoelectron spectroscopy,\nand an extensive computational evolutionary search, we find that Pt\natoms significantly reconfigure the support lattice to facilitate\na pseudolinear coordination to surface oxygen atoms. Despite breaking\nthree surface Fe–O bonds, this geometry is favored by 0.84\neV over the best configuration involving an unperturbed support. We\nsuggest that the linear O–Pt–O configuration is common\nin reactive Pt-based SAC systems because it balances thermal stability\nwith the ability to adsorb reactants from the gas phase. Moreover,\nwe conclude that extensive structural searches are necessary to determine\nrealistic active site geometries in single-atom catalysis.