Direct Visualization of Plasmon- Induced Hole Injection in Electroactive Luminescent Monolayers on Gold Nanoparticles

Area of Science:

• Nanotechnology
• Electrochemistry
• Photophysics

Background:

• Plasmon activation of metallic nanoparticles influences their optical and electronic properties.
• Redox-active monolayers on nanoparticles can mediate electron transfer.
• Simultaneous optical and electrochemical measurements provide complementary information.

Purpose of the Study:

• To demonstrate dual and simultaneous modulation of fluorescence intensity and electrochemical current using plasmon activation.
• To investigate the mechanism of fluorescence and current changes induced by plasmon excitation and electrochemical potential.
• To explore the potential of this system for applications in photoelectrocatalysis.

Main Methods:

• Utilizing scanning electrochemical microscopy (SECM) combined with fluorescence microscopy.
• Employing fluorescent redox monolayers grafted onto gold nanoparticles.
• Analyzing electrochemical and optical responses under varying conditions.

Main Results:

• Observed dual modulation of fluorescence intensity and electrochemical current upon plasmon activation.
• Demonstrated direct hole injection from plasmonically excited gold nanoparticles into the grafted monolayer.
• Reported unprecedented fluorescence enhancement under simultaneous electroreduction and plasmon activation, contrasting with quenching observed for individual processes.
• Showcased significantly larger electrochemical current enhancement for functionalized nanoparticles compared to bare ones under plasmon activation.

Conclusions:

• The findings confirm direct hole injection as the mechanism for the observed phenomena.
• The study highlights a novel approach for enhancing fluorescence and electrochemical signals.
• This work paves the way for new strategies in photoelectrocatalysis utilizing plasmon-enhanced effects.