Light-Induced Voltages in Catalysis by Plasmonic Nanostructures.

Area of Science:

• Physical Chemistry
• Materials Science
• Nanotechnology

Background:

• Plasmonic nanostructures exhibit strong light-matter interactions due to localized surface plasmon resonances (LSPRs).
• LSPRs enable plasmonic catalysis, where photoexcitation of nanostructures enhances chemical reaction rates.
• Existing explanations for plasmonic catalysis involve enhanced electric fields and hot carriers.

Purpose of the Study:

• To investigate the role of light-induced potentials (photopotentials) in plasmonic catalysis.
• To explore how photopotentials modify the energetics and kinetics of chemical reactions on noble metal nanoparticles.
• To present the photopotential model as a complementary mechanism to existing plasmonic catalysis theories.

Main Methods:

• Investigated the generation of photopotentials via asymmetric charge transfer from nanostructures to solution-phase acceptors upon LSPR excitation.
• Measured photopotentials up to a few hundred millivolts.
• Analyzed the effect of photopotentials on redox and electrochemical reactions on noble metal nanoparticles.

Main Results:

• Plasmonic excitation induces a measurable photopotential on nanoparticles.
• This photopotential lowers activation barriers for redox reactions and supplements applied potentials in electrochemical reactions.
• The photopotential model successfully explains observed rate enhancements and trends with light intensity and photon energy.

Conclusions:

• Light-induced potentials are a significant, often overlooked, factor in plasmonic catalysis.
• The photopotential model complements existing mechanisms, providing a more comprehensive understanding of plasmonic enhancement.
• Photopotentials offer a tunable parameter for controlling the activity and selectivity of noble metal nanoparticle catalysts.