Ultrafast Dynamics of Plasmon-Exciton Interaction of Ag Nanowire-Graphene Hybrids for Surface Catalytic Reactions

TL;DR

This study investigates ultrafast plasmon-exciton interactions in graphene-Ag nanowire hybrids using femtosecond spectroscopy, revealing enhanced hot electron transfer and catalytic efficiency for surface reactions.

Contribution

It provides the first detailed femtosecond-resolved analysis of plasmon-exciton dynamics in graphene-Ag nanowire hybrids, demonstrating their potential for improved plasmon-driven catalysis.

Findings

Hot electron transfer occurs in about 534 fs.

Graphene-Ag hybrids significantly boost surface catalytic reaction efficiency.

Strong plasmon-exciton coupling enhances hot electron accumulation.

Abstract

Using the ultrafast pump-probe transient absorption spectroscopy, the femtosecond-resolved plasmon-exciton interaction of graphene-Ag nanowire hybrids is experimentally investigated, in the VIS-NIR region. The plasmonic lifetime of Ag nanowire is about 150 femtosecond (fs). For a single layer of graphene, the fast dynamic process at 275 fs is due to the excitation of graphene excitons, and the slow process at 1.4 picosecond (ps) is due to the plasmonic hot electron interaction with phonons of graphene. For the graphene-Ag nanowire hybrids, the time scale of the plasmon-induced hot electron transferring to graphene is 534 fs, and the metal plasmon enhanced graphene plasmon is about 3.2 ps in the VIS region. The graphene-Ag nanowire hybrids can be used for plasmon-driven chemical reactions. This graphene-mediated surface-enhanced Raman scattering substrate significantly increases the probability and efficiency of surface catalytic reactions co-driven by graphene-Ag nanowire hybridization, in comparison with reactions individually driven by monolayer graphene or single Ag nanowire. This implies that the graphene-Ag nanowire hybrids can not only lead to a significant accumulation of high-density hot electrons, but also significantly increase the plasmon-to-electron conversion efficiency, due to strong plasmon-exciton coupling.