Atomically controlled electrochemical nucleation at superionic solid electrolyte surfaces.

Area of Science:

• Surface Science and Electrochemistry
• Atomic-Scale Imaging and Analysis
• Solid-State Ionics and Nanomaterials

Background:

• Understanding electrochemical equilibrium and interfacial charge/mass transfer at the atomic scale is crucial for physicochemical processes.
• Previous studies were limited by phase instabilities and instrumentation at atomic dimensions.

Purpose of the Study:

• To achieve ultimate lateral, mass, and charge resolution during electrochemical silver (Ag) phase formation.
• To investigate Ag critical nucleus formation kinetics and energetics at the atomic level.
• To explore the potential of this technique for elucidating atomic switch mechanisms and other electrochemical systems.

Main Methods:

• Electrochemical deposition of Ag on RbAg(4)I(5) superionic conductor thin films.
• Scanning Tunneling Microscopy (STM) with atomic resolution.
• Inclusion of electron donors in the solid electrolyte to enable high-resolution STM measurements.

Main Results:

• Achieved ultimate lateral, mass, and charge resolution during electrochemical Ag phase formation.
• Demonstrated that Ag critical nucleus formation is the rate-limiting step.
• Observed that the Gibbs energy for nucleation has discrete values, and the critical nucleus size is constant over a range of applied potentials.

Conclusions:

• The study provides unprecedented atomic-scale insight into electrochemical phase formation.
• The findings are critical for understanding atomic switches and related electrochemical phenomena.
• The developed approach is extendable to various other electrochemical systems.