Unravelling CO adsorption on model single-atom catalysts

TL;DR

This study investigates how different single-atom catalysts on Fe3O4(001) influence CO adsorption, revealing that local environment and charge transfer significantly alter adsorption strength and structural stability.

Contribution

The paper provides detailed insights into how the local atomic environment affects CO binding on various single-atom catalysts supported on Fe3O4(001).

Findings

CO adsorption strength varies among different metal single atoms.

Charge transfer modifies metal d-states and influences bond strength.

Structural relaxations upon CO adsorption depend on local geometry.

Abstract

Understanding how the local environment of a single-atom catalyst affects stability and reactivity remains a significant challenge. We present an in-depth study of Cu1, Ag1, Au1, Ni1, Pd1, Pt1, Rh1, and Ir1 species on Fe3O4(001); a model support where all metals occupy the same 2-fold coordinated adsorption site upon deposition at room temperature. Surface science techniques revealed that CO adsorption strength at single metal sites differs from the respective metal surfaces and supported clusters. Charge transfer into the support modifies the d-states of the metal atom and the strength of the metal-CO bond. These effects could strengthen the bond (as for Ag1-CO) or weaken it (as for Ni1-CO), but CO-induced structural distortions reduce adsorption energies from those expected based on electronic structure alone. The extent of the relaxations depends on the local geometry and could be predicted by analogy to coordination chemistry.