Insights into Chemical Changes Causing Transient Potential Patterns during Cobalt Electrodeposition: An Operando...

Area of Science:

• Electrochemistry
• Materials Science
• Surface Chemistry

Background:

• Transient potential oscillations are critical in self-organized systems, influencing electrodeposited metallic film microstructure.
• Understanding the chemical reactions behind these oscillations is vital for optimizing electrodeposition processes.

Purpose of the Study:

• To investigate the chemical mechanisms underlying two distinct potential oscillations observed during galvanostatic cobalt deposition with butynediol.
• To provide direct spectroscopic evidence of the reactions involved.

Main Methods:

• Utilized *operando* shell-isolated nanoparticle-enhanced Raman spectroscopy to monitor chemical changes during deposition.
• Analyzed potential oscillatory patterns and correlated them with mass-transfer limitations.

Main Results:

• Observed direct spectroscopic evidence of adsorbed hydrogen scavenging by butynediol.
• Identified cobalt hydroxide (Co(OH)₂) formation and removal processes.
• Demonstrated that mass transfer of butynediol and protons limits these reactions.
• Correlated four distinct oscillatory segments with mass-transfer limitations of either protons or butynediol.

Conclusions:

• The study elucidates the chemical dynamics governing potential oscillations in cobalt electrodeposition.
• Findings enhance the understanding of how mass transfer influences oscillatory behavior and microstructure formation.
• Provides insights for designing more efficient electrodeposition systems for metallic films.