Benchmarking Nanoscale Electrochemistry in Operando Transmission Electron Microscopy with a Standard Reference...

Area of Science:

• Electrochemistry
• Materials Science
• Nanotechnology

Background:

• Operando/in situ methods advance understanding of nanoscale dynamics at solid-liquid interfaces.
• Electrochemical liquid-cell scanning transmission electron microscopy (EC-STEM) allows real-time structural evolution tracking.
• Precise potential control in EC-STEM is challenging due to reference electrode incompatibility.

Purpose of the Study:

• To develop a reliable real-time reference electrode calibration for EC-STEM.
• To investigate copper nucleation and growth mechanisms under electrochemical conditions.
• To provide guidance for applications requiring minimized dendrite formation.

Main Methods:

• Real-time reference electrode (RE) calibration using a metal-bridge strategy.
• On-chip platinum (Pt) pseudo-reference electrode connected to an external silver/silver chloride (Ag/AgCl) RE.
• Electrochemical benchmarking with three redox couples.
• Operando EC-STEM for nanoscale structural evolution tracking.

Main Results:

• Confirmed reliable potential referencing and Nernstian hydrogen kinetics on Pt across a wide pH range (1-12).
• Observed accelerated copper nucleation and growth at higher overpotentials.
• Identified Cu2+ depletion as the driver for the transition from mossy to dendritic growth.
• Demonstrated suppression of dendritic growth via external electrolyte flow.

Conclusions:

• The metal-bridge strategy enables accurate potential control in EC-STEM.
• Understanding copper growth mechanisms provides insights for energy and industrial applications.
• External electrolyte flow can mitigate detrimental dendritic growth.