Dynamic Activation of Single Atom Catalysts by Reaction Intermediates: Conversion of Formic Acid on Rh-Fe3O4(001)

03 January 2024, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The stability and activity of supported single-atom catalysts (SACs) represent critical yet opposing factors limiting our ability to explore and exploit their unique properties. This study demonstrates the operation of a switchable catalyst that is activated in the presence of surface intermediates and reverts back to a stable but inactive form when the reaction is completed. We employ atomically defined Rh-Fe3O4(001) catalysts to demonstrate how structurally stable Rh, bound in surface octahedral Fe sites, gets destabilized to form highly active Rh adatoms and small clusters. Conversion of formic acid, leading initially to surface formate and hydroxyl species, is employed as a model reaction to probe the dynamics of such processes. We find that surface hydroxyl recombination to water through the Mars van Krevelen mechanism reduces Rh coordination, triggering its conversion to active Rh adatoms. Since such lattice oxygen exchange is observed in many acid-base and redox chemistries, the process can be broadly applicable to controlling the activation of the range of SACs.


Single atom catalyst
Dynamic structural evolution
Scanning tunneling microscopy
Temperature programmed reaction spectroscopy
X-ray photoelectron spectroscopy
iron oxide

Supplementary materials

Methods and Suplementary XPS Spectra
The description of experimental methods and sample preparation. The evolution of 2p Fe XPS of the initial Rhoct/Fe3O4(001) in the presence of surface intermediates.


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