Ordered Array of Single Au Adatoms with Remarkable Thermal Stability: Au/Fe3O4(001)

TL;DR

This study uses STM to show that gold adatoms on Fe3O4(001) surface form a thermally stable, ordered array at specific sites, maintaining stability up to 400°C, which is promising for single-atom reactivity studies.

Contribution

It demonstrates the formation of a thermally stable, ordered array of single Au adatoms on Fe3O4(001) surface at room temperature, with potential applications in surface chemistry.

Findings

Au adatoms adsorb at narrow sites on Fe3O4(001)

Adatoms remain stable up to 400°C without sintering

Ordered Au array could be used for probing chemical reactivity

Abstract

We present a Scanning Tunneling Microscopy (STM) investigation of gold deposited at the magnetite Fe3O4(001) surface at room temperature. This surface forms a reconstruction with (\surd2\times\surd2)R45{\deg} symmetry, where pairs of Fe and neighboring O ions are slightly displaced laterally, forming undulating rows with 'narrow' and 'wide' adsorption sites. At fractional monolayer coverages, single Au adatoms adsorb exclusively at the narrow sites, with no significant sintering up to annealing temperatures of 400 {\deg}C. The strong preference for this site is possibly related to charge and orbital ordering within the first subsurface layer of the reconstructed Fe3O4(001) surface. Because of their high thermal stability, the ordered Au atoms at Fe3O4(001)- (\surd2\times\surd2)R45{\deg} could provide useful for probing the chemical reactivity of single atomic species.