Tracking Electrochemistry on Single Nanoparticles with Surface-Enhanced Raman Scattering Spectroscopy and Microscopy

Area of Science:

• Electrochemistry
• Nanotechnology
• Spectroscopy

Background:

• Nanoparticle performance varies greatly, but traditional methods average results, hiding individual nanoparticle behavior.
• Existing electrochemical methods lack molecular structural information.
• Surface-enhanced Raman scattering (SERS) offers a way to study single nanoparticles and their surface species.

Purpose of the Study:

• To develop and demonstrate a protocol for tracking electrochemical reactions on single nanoparticles.
• To combine electrochemical measurements with SERS microscopy for molecular-level insights.
• To investigate the electrochemical oxidation-reduction of Nile Blue (NB) on individual silver (Ag) nanoparticles.

Main Methods:

• Fabrication of Ag nanoparticles on a Ag film to create a plasmonic substrate.
• Utilizing a donut-shaped SERS emission pattern for unambiguous single nanoparticle identification.
• Adapting the SERS substrate as a working electrode in an electrochemical cell for an inverted optical microscope.

Main Results:

• A detailed protocol for Ag nanoparticle fabrication and SERS substrate preparation was established.
• Donut-shaped SERS emission patterns were used to identify individual Ag nanoparticles.
• The electrochemical oxidation-reduction of Nile Blue (NB) on a single Ag nanoparticle was successfully tracked.

Conclusions:

• The developed SERS microscopy protocol enables the study of electrochemical reactions at the single nanoparticle level.
• This method provides molecular information, overcoming limitations of ensemble electrochemical techniques.
• The protocol is adaptable for studying diverse electrochemical reactions on various individual nanoparticles.