A Multitechnique Study of C₂H₄ Adsorption on a Model Single-Atom Rh₁ Catalyst

Area of Science:

• Surface science
• Heterogeneous catalysis
• Materials science

Background:

• Single-atom catalysts (SACs) offer precise control over active sites for structure-function relationship studies.
• Understanding adatom coordination and support interactions is crucial for designing efficient catalysts.

Purpose of the Study:

• Investigate ethylene (C2H4) interaction with a model Rh/Fe3O4(001) catalyst.
• Differentiate the behavior of various Rh species: adatoms (2-, 5-, 6-fold coordination) and clusters.
• Elucidate the role of Rh migration on ethylene adsorption and desorption.

Main Methods:

• Utilized multiple surface-sensitive techniques.
• Performed density functional theory (DFT) calculations.
• Analyzed thermal desorption spectroscopy (TDS) data.

Main Results:

• Strongest C2H4 adsorption observed at 2-fold coordinated Rh (Rh1) with -2.26 eV adsorption energy.
• Rh migration to substitutional sites led to lower-than-expected desorption temperatures.
• 5-fold coordinated Rh sites exhibited weaker adsorption (-1.49 eV), complicated by cluster formation and heterogeneity.

Conclusions:

• Rh adatom migration significantly influences C2H4 binding and thermal stability.
• Catalyst heterogeneity and cluster formation complicate the interpretation of adsorption/desorption behavior.
• Precise determination of active sites and their stability is essential for advancing SAC development.