The interface ionic liquid(s)/electrode(s): in situ STM and AFM measurements.

Area of Science:

• Electrochemistry
• Surface Science
• Materials Science

Background:

• Ionic liquids are promising electrolytes due to their stability.
• Understanding the electrode/ionic liquid interface is crucial for electrochemical applications.
• The structure of this interface is known to be complex.

Purpose of the Study:

• To investigate the nanoscale structure of the interfacial layer between an ionic liquid and Au(111).
• To examine how electrode potential and solute addition affect the interfacial structure.

Main Methods:

• In situ scanning tunneling microscopy (STM) was used to observe interfacial layers.
• Atomic force microscopy (AFM) data on anion adsorption and forces were incorporated.

Main Results:

• STM revealed the formation of layers/islands with increasing electrode potential.
• Anion adsorption strengthens with increasing potential, forming multiple layers.
• These interfacial layers exhibit nanoscale structure and are non-uniform.
• Solute addition, specifically LiCl, significantly alters the interfacial structure and forces.

Conclusions:

• The electrode/ionic liquid interface is highly complex and structured at the nanoscale.
• Electrode potential and solute presence are critical factors controlling interfacial layer formation and properties.
• Solutes can drastically change the nature of forces at the ionic liquid/electrode interface.