Surface charge--induced ordering of the au(111) surface

Area of Science:

• Electrochemistry
• Surface Science
• Materials Science

Background:

• The atomic arrangement of metal surfaces is crucial for their electrochemical properties.
• Understanding surface reconstruction at the electrode/electrolyte interface is key to controlling interfacial reactions.

Purpose of the Study:

• To investigate the impact of surface charge on the microscopic structure of gold surface atoms.
• To determine the critical surface charge density at which gold surface reconstruction occurs.

Main Methods:

• Synchrotron surface x-ray scattering (SXS) was employed to study the Au(111)/electrolyte interface.
• Electrode potential was systematically varied to control surface charge density.
• Experiments were conducted in dilute solutions of NaF, NaCl, and NaBr to assess the role of specific anions.

Main Results:

• A reversible phase transition of the gold surface layer was observed between a (1 x 1) bulk termination and a (23 x radical3) reconstructed phase.
• This phase transition was found to occur at a consistent induced surface charge density of 0.07 +/- 0.02 electron per atom across different halide solutions.
• The results indicate that surface charge density, rather than specific adsorbate interactions, is the primary driver of this reconstruction.

Conclusions:

• Surface charge is a critical factor governing the atomic arrangement of gold surfaces at the electrochemical interface.
• The observed phase transition is a universal phenomenon driven by the magnitude of surface charge, independent of the electrolyte's specific anion.
• These findings provide fundamental insights into surface reconstruction mechanisms relevant to electrocatalysis and surface chemistry.