Abstract
Abstract The single-layer graphene (SLG)-coupled nanowire (NW) hybrid plasmonic gap mode (PGM)-driven molecular catalytic reaction was investigated experimentally and theoretically. First, an SLG-coupled NW was constructed, then the surface-enhanced Raman scattering (SERS) effect of graphene in the hybrid plasmonic gap was studied via the normal and oblique incidence of excitation light. The SERS peaks of the D and G of graphene are more intensely enhanced by oblique incidence than by normal incidence. Furthermore, the catalytic reaction of the dimerization of the 4-nitrobenzenethiol molecule to p,p′-dimercaptoazobenzene molecule driven by PGM was carried out by SERS. It was demonstrated that the efficiency of the PGM-driven catalytic reaction is much higher for oblique incidence than that for normal incidence. The mechanism of the PGM-driven catalytic reaction was studied by a finite-difference time-domain numerical simulation. When the PGM is excited by oblique incidence with θ = 30°, the coupling between the NW and SLG/SiO2 substrate increases to the maximum value. This is clearly evidenced by the excitation of a vertical bonding dipolar plasmon mode under the dipole approximation. The theoretical and experimental results were consistent with each other. This research may open up a pathway toward controlling PGM-driven catalytic reactions through polarization changes in excitation laser incidence on single anisotropic nanostructures.
Highlights
Surface plasmon resonance (SPR) is the resonant collective oscillation of conduction electrons produced near the interface between a metal and a dielectric when light irradiates the metal nanostructure [1,2,3,4,5,6]
This study addresses several urgent problems associated with the vertical bonding dipole plasmon (V-BDP) mode that needed to be resolved, including how the V-BDP mode can be induced using changes in the incidence angles of exciting light, how the surface-enhanced Raman scattering (SERS) effect is enhanced by the V-BDP mode, and the efficiency of the catalytic reaction driven by the V-BDP mode
NWs possess the merit of a well-defined anisotropy in the transverse and longitudinal directions; this can be used as a benchmark system for studying the polarizationdependent local surface plasmon resonance (LSPR) properties [30]
Summary
Surface plasmon resonance (SPR) is the resonant collective oscillation of conduction electrons produced near the interface between a metal and a dielectric when light irradiates the metal nanostructure [1,2,3,4,5,6]. Z. Li et al.: Graphene-coupled nanowire hybrid plasmonic gap mode–driven catalytic reaction revealed by SERS (LSPs) that can strongly confine light to the deep subwavelength volume to produce intense electrical fields. Li et al.: Graphene-coupled nanowire hybrid plasmonic gap mode–driven catalytic reaction revealed by SERS (LSPs) that can strongly confine light to the deep subwavelength volume to produce intense electrical fields They can function as photocatalysts and as SERS signal enhancers. This study addresses several urgent problems associated with the V-BDP mode that needed to be resolved, including how the V-BDP mode can be induced using changes in the incidence angles of exciting light, how the SERS effect is enhanced by the V-BDP mode, and the efficiency of the catalytic reaction driven by the V-BDP mode. The effect of V-BDP under different incidence angles was investigated by theoretical simulation and conclusions were drawn
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