Plasmon-Enhanced Chemical Reaction at the Hot Spots of End-to-End Assembled Gold Nanorods

Abstract

Herein, we report a centrifugal force-driven end-to-end assembly of gold nanorods (Au NRs) via the H-bonded interaction of para-aminothiophenol (p-ATP) selectively bound to the longitudinal ends of the Au NRs. The plasmonic hot spots generated due to the Au NR assembly served as a catalytic center for carrying out the photochemical coupling reaction of p-ATP to dimercaptoazobenzene (DMAB). We also demonstrate the degradation of DMAB in the presence of hydrogen peroxide (H2O2) at the plasmonic hot spot. The coupling reaction was carried out at the hot spot of the assembled Au NRs upon surface plasmon excitation using a 632.8 nm laser. Surface-enhanced Raman scattering (SERS) kinetic data indicated that the plasmon-mediated coupling reaction was 1.6-fold faster at the plasmonic hot spot of the assembled Au NRs than that on the surface of the longitudinal end of the Au NRs. This, therefore, showed a new way of carrying out photocatalytic reactions at the plasmonic hot spot with a higher reaction rate.