Visualizing Surface-Subsurface Cu Atom Exchange at the FeO/Pt(111) Surface Induced by CO Adsorption at 150 K

Area of Science:

• Surface science
• Heterogeneous catalysis
• Materials science

Background:

• Surface atomic restructuring under reaction conditions is well-understood.
• The influence of reaction gases on subsurface atomic structures remains largely unexplored.

Purpose of the Study:

• To investigate the impact of carbon monoxide (CO) on subsurface copper (Cu) atoms within a FeO/Pt(111) model catalyst.
• To explore the mechanisms of atomic rearrangement in buried catalyst structures.

Main Methods:

• Experimental studies involving CO exposure to supported Cu/FeO/Pt(111) and buried FeO/Cu/Pt(111) systems.
• Ultrahigh vacuum (UHV) techniques for gas exposure and temperature manipulation.
• Density Functional Theory (DFT) calculations to elucidate atomic restructuring mechanisms.

Main Results:

• Copper clusters (Cu) on FeO/Pt(111) transform into surface copper-carbon complexes (CuCO/FeO/Pt) upon CO exposure at 78 K.
• Buried Cu clusters (FeO/Cu/Pt) also form surface CuCO complexes on FeO/Pt(111) after CO adsorption at 150 K.
• Place exchange between surface and subsurface Cu atoms is mediated by CO adsorption and subsequent UHV annealing.
• Calculations show CO adsorption restructures the FeO film, creating diffusion pathways for Cu atoms.

Conclusions:

• Subsurface atoms can undergo significant restructuring driven by reaction gases, influencing catalytic activity.
• The formation of surface CuCO complexes from buried Cu atoms highlights the dynamic nature of catalyst surfaces under reaction conditions.
• Understanding subsurface restructuring is crucial for optimizing heterogeneous catalyst design and performance.