Interfacial design of gold/silver core–shell nanostars for plasmon-enhanced photocatalytic coupling of 4-aminothiophenol

Abstract

Chemical reactions under mild conditions mediated by localized surface plasmon resonance (LSPR) of metals have emerged as a functional research field. In the present study, we report an interfacial designing procedure for the fabrication of a class of bimetallic hybrid nanomaterials as a profoundly active photocatalyst for the conversion of para-aminothiophenol (PATP) into 4,4′-dimercaptoazobenzene. For this purpose, core–shell nanostars composed of gold (core) and silver (shell) (Au/Ag NSs) were utilized as both surface-enhanced Raman scattering substrate and plasmon driven catalyst under 532 nm laser excitation. Au/Ag NSs with sharp tips display excellent surface-enhanced Raman scattering (SERS) efficiency of PATP. Employing the SERS study, it has been found that PATP rapidly converts into its dimerized product DMAB within few seconds by surface photochemical reaction in the Au–Ag heterojunction of core–shell nanostars. Au/Ag NSs with multiple sharp tips exhibit intense LSPR and highly strong electric fields are created at the tips, which enables the generation of hot electrons responsible for the rapid conversion reaction. Such well-designed interfacial bimetallic nanostars could have potential applications in surface enhanced spectroscopy, biosensing, and photoinduced surface catalysis.