Blocking Hot Electron Emission by SiO2 Coating Plasmonic Nanostructures

Abstract

The transformation of para-aminothiophenol (PATP) to dimercaptoazobenzene (DMAB) is widely believed to be due to the emission of hot electrons from the plasmonic nanostructures,1 which are generated during the decay of the surface plasmons (LSPPs). Our aim here is to separate the catalytic activity of plasmonic nanostructures from their SERS activity by using a 5 nm thick silicon dioxide (SiO2) layer. This layer blocks hot electrons from reaching the PATP molecules but lets the electromagnetic field penetrate, allowing us to measure the SERS of the monomer without triggering a chemical reaction. The SERS measurement was performed at 633 nm on two-dimensional gold nanoparticle (2D AuNP) arrays covered with/without thin SiO2.