Near-field and photocatalytic properties of mono- and bimetallic nanostructures monitored by nanocavity surface-enhanced Raman scattering

Localized surface plasmon resonances (LSPR) generated in a particle-film nanocavity enhance electric fields within nanoscale volume. LSPR can also decay into hot carriers, highly energetic species that catalyze photocatalytic reactions molecular analytes located close proximity to metal surfaces. In this study, we examined the intensity of field (near-field) and properties plasmonic nanocavities formed by single nanoparticles (SNP) on nanoplates (SNL). Using 4-nitrobenzenethiol (4-NBT) as reporter, determined near-field responses, well measured rates 4-NBT dimerization 4,4-dimercaptoazobenzene (DMAB) gold (Au) SNP AuSNL (Au-Au), AuSNP AgSNL (Au-Ag), AgSNP (Ag-Au), (Ag-Ag) using 532, 660, 785 nm excitations. We observed strongest signals at 660 all systems is found be substantially red-shifted relative corresponding nanoparticles. DMAB formation were significantly greater heterometal (Au-Ag Ag-Au) compared their monometallic counterparts (Au-Au Ag-Ag). These results point drastic differences mono bimetallic nanostructures.