Plasmon-driven reaction controlled by the number of graphene layers and localized surface plasmon distribution during optical excitation

Graphene-plasmonic hybrid platforms have attracted an enormous amount of interest in surface-enhanced Raman scattering(SERS);however,the mechanism of employing graphene is still ambiguous,so clarification about the complex interaction among molecules,graphene,and plasmon processes is urgently needed.We report that the number of graphene layers controlled the plasmon-driven,surface-catalyzed reaction that converts para-aminothiophenol(PATP)-to-p,p'-dimercaptoazobenzene(DMAB)on chemically inert,graphene-coated,silver bowtie nanoantenna arrays.The catalytic reaction was monitored by SERS,which revealed that the catalytic reaction occurred on the chemical inertness monolayer graphene(1G)-coated silver nanostructures.The introduction of 1G enhances the plasmon-driven surface-catalyzed reaction of the conversion of PATP-to-p,p'-DMAB.The chemical reaction is suppressed by bilayer graphene.In the process of the catalytic reaction,the electron transfer from the PATP molecule to 1G-coated silver nanostructures.Subsequently,the transferred electrons on the graphene recombine with the hot-hole produced by the localized surface plasmon resonance of silver nanostructures.Then,a couple of PATP molecules lost electrons are catalyzed into the p,p'-DMAB molecule on the graphene surface.The experimental results were further supported by the finite-difference time-domain method and quantum chemical calculations.