Coadsorbate-Induced Reversal of Solid-Liquid Interface Dynamics.

Area of Science:

• Surface Science
• Electrochemistry
• Physical Chemistry

Background:

• Coadsorbed anions significantly impact surface reactivity and dynamics at solid-liquid interfaces.
• Understanding these spectator species is crucial for controlling surface processes.

Purpose of the Study:

• To investigate how the chemical nature of spectator anions influences the surface diffusion of adsorbed atoms.
• To elucidate the microscopic mechanisms governing surface diffusion on electrode surfaces.

Main Methods:

• Quantitative in situ video scanning tunneling microscopy (STM) for surface diffusion measurements.
• Density Functional Theory (DFT) calculations to explore diffusion mechanisms.
• Electrochemical experiments on Cu(100) electrodes in aqueous solutions.

Main Results:

• Surface diffusion of sulfur atoms on Cu(100) exhibits a strong potential dependence, with opposite signs for bromide and chloride spectator anions.
• Anion-induced differences in sulfur diffusion mechanisms were identified, including exchange diffusion on bromide-covered surfaces.
• Copper vacancy formation was observed in the bromide system, supporting the proposed exchange diffusion mechanism.

Conclusions:

• The chemical nature of spectator anions is a primary determinant of microscopic dynamic behavior at interfaces.
• Anion-specific diffusion mechanisms, such as sulfur exchange diffusion, can occur and lead to observable surface modifications.
• This work highlights the importance of considering spectator species in surface electrochemistry and catalysis.