Label‐free SERS monitoring of hydride reduction catalyzed by Au nanostars

Abstract

Surface‐enhanced Raman scattering (SERS) is a promising molecular spectroscopic technique to study chemical reactions catalyzed by nobel metal nanoparticles. Herein, the Au nanostar (NS)‐catalyzed hydride reduction of 4‐nitrothiophenol to 4‐aminothiophenol chemisorbed at the metal/solution interface was followed by SERS. By developing a simple two‐step route, we demonstrated shape‐controlled synthesis and morphology‐dependent catalytic activity of AuNSs. The kinetic SERS monitoring of the reaction on the Au surface indicates that the catalytic activity of the AuNSs correlates with the sharpness of their tips. This is consistent with the known size‐dependent catalytic activity of small AuNPs. In contrast to the complex bifunctional nanostructures reported previously, this work shows that AuNSs are bifunctional nanostructures suitable for investigating Au‐catalyzed reactions. A proposed electron transfer mechanism explains the reduction of 4‐nitrothiophenol to 4‐aminothiophenol on AuNS tips where –NO2 groups have no direct contact with the catalyst. Copyright © 2016 John Wiley & Sons, Ltd.