Can Light Alter the Yield of Plasmon-Driven Reactions on Gold and Gold-Palladium Nanoplates?

Abstract

Noble-metal nanostructures, as well as their bimetallic analogues, catalyze a broad spectrum of plasmon-driven reactions. Catalytic properties of such nanostructures arise from light-generated surface plasmon resonances that decay forming transient hot electrons and holes. Hot carriers with "slower" dissipation rates accumulate on nanostructures generating an electrostatic potential. In this study, we examine whether light intensity can alter the electrostatic potential of mono- and bimetallic nanostructures changing yields of plasmon-driven reactions. Using tip-enhanced Raman spectroscopy (TERS), we quantified the yield of plasmon-driven transformations of 4-nitrobenzenethiol (4-NBT) and 3-mercaptobenzoic acid (3-MBA) on gold and gold-palladium nanoplates (AuNPs and Au@PdNPs, respectively). We found that on AuNPs 3-MBA decarboxylated forming thiophenol (TP), whereas 4-NBT was reduced to DMAB. The yield of both TP and DMAB gradually increased with increasing light intensity. On Au@PdNPs, 3-MBA could be reduced to 3-mercaptophenylmethanol (3-MPM), the yield of which was also directly dependent on the light intensity.