Atomic-resolution electrochemistry with the atomic force microscope: copper deposition on gold.

Area of Science:

• Electrochemistry
• Surface Science
• Nanotechnology

Background:

• Understanding electrode surface behavior is crucial for electrochemical applications.
• Atomic-level imaging provides insights into interfacial processes.

Purpose of the Study:

• To visualize and characterize copper deposition and stripping on Au(111) at atomic resolution.
• To investigate the influence of electrolyte composition on copper monolayer structure.
• To observe the dynamics of electrochemical cycles at the electrode-electrolyte interface.

Main Methods:

• Atomic Force Microscopy (AFM) under electrochemical potential control in fluid electrolytes.
• In situ imaging of Au(111) electrode surfaces during copper electrodeposition and stripping.
• Analysis of atomic lattice structures and spacing.

Main Results:

• Observed distinct copper (Cu) monolayer structures on Au(111) depending on the electrolyte (perchloric acid vs. sulfate).
• Cu atoms formed a close-packed lattice (0.29 nm spacing) in perchloric acid and a more open lattice (0.49 nm spacing) in sulfate.
• Thicker Cu layers adopted a consistent (111)-oriented structure (0.26 nm spacing).
• Revealed terrace patterns during Cu dissolution and a 30-degree lattice rotation between Cu monolayer and Au substrate.

Conclusions:

• Electrolyte composition significantly impacts the atomic arrangement of underpotential-deposited copper monolayers.
• AFM provides unprecedented atomic-level detail of electrochemical surface transformations.
• The study elucidates the structural evolution of copper on gold during electrochemical cycling.