How Does a Plasmon-Induced Hot Charge Carrier Break a C-C Bond?

Area of Science:

• Surface chemistry
• Nanoparticle catalysis
• Photochemistry

Background:

• Hot-electron chemistry at gold nanoparticle (AuNP) surfaces is crucial for plasmonic photocatalysis and photovoltaics.
• Nonradiative decay of surface plasmons generates hot charge carriers that drive chemical reactions on adsorbates.
• Current plasmon-driven reactions are limited, primarily to dimerization reactions.

Purpose of the Study:

• To explore a new class of plasmon-driven reactions involving unimolecular bond cleavage.
• To elucidate the mechanism of decarboxylation for 4-mercaptobenzoic acid.
• To extend the mechanism to β-cleavage reactions of 4-mercaptobenzyl alcohol.

Main Methods:

• Fabrication of well-controlled nanogap systems.
• Utilizing sensitive Raman spectroscopy.
• Systematic variation of experimental conditions (laser wavelengths, interface materials, pH, ambient gases).

Main Results:

• Unveiled the mechanism for the decarboxylation of 4-mercaptobenzoic acid.
• Extended the mechanism to explain the β-cleavage of 4-mercaptobenzyl alcohol.
• Tracked hot charge carrier transfer from formation to reactant interaction.

Conclusions:

• Demonstrated new unimolecular C-C bond cleavage reactions driven by plasmon excitation.
• Provided insights into the fundamental processes of hot charge carrier generation, transfer, and reaction induction.
• Expanded the scope of known plasmon-driven chemical transformations.