Graphene as an Electron Shuttle for Silver Deoxidation: Removing a Key Barrier to Plasmonics and Metamaterials for SERS in the Visible

Abstract

The role of graphene in enabling deoxidation of silver nanostructures, thereby contributing to enhance plasmonic properties and to improve the temporal stability of graphene/silver hybrids for both general plasmonic and meta‐materials applications, as well as for surface enhanced Raman scattering (SERS) substrates, is demonstrated. The chemical mechanism occurring at the graphene–silver oxide interface is based on the reduction of silver oxide triggered by graphene that acts as a shuttle of electrons and as a kind of catalyst in the deoxidation. A mechanism is formulated, combining elements of electron transfer, role of defects in graphene, and electrochemical potentials of graphene, silver, and oxygen. Therefore, the formulated model represents a step forward from the simple view of graphene as barrier to oxygen diffusion proposed so far in literature. Single layer graphene grown by chemical vapor deposition is transferred onto silver thin films, a periodic silver fishnet structure fabricated by nanoimprint lithography, and onto silver nanoparticle ensembles supporting a localized surface plasmon resonance in the visible range. Through the study of these nanostructured graphene/Ag hybrids, the effectiveness of graphene in preventing and reducing oxidation of silver plasmonic structures, keeping silver in a metallic state over months at air exposure, is demonstrated. The enhanced and stable plasmonic properties of the silver‐fishnet/graphene hybrids are evaluated through their SERS response for detecting benzyl mercaptane.

Graphene oxide wrapped individual silver nanocomposites with improved stability for surface-enhanced Raman scattering

“…For example, Ag decorated GO or GO covered Ag substrates have been used for detecting aromatic molecules, taking advantage of the strong interaction between these molecules with graphene surface. [38][39][40]42 In addition, sandwich structures have also been constructed where Ag nanoparticles were placed in between GO sheaths. 36,37 Very recently, CVD grown graphene on top of noble metal nanostructures as a pinholefree isolating shell has been demonstrated as an effective method to improve stability and enhance sensitivity of the SERS substrate.…”

Synergistic Effects of Wrinkled Graphene and Plasmonics in Stretchable Hybrid Platform for Surface‐Enhanced Raman Spectroscopy

“…Among these composites, graphene/Au hybrid structures have drawn significant attention because of synergistic effect of Au's high SERS activity and graphene's amazing Raman scattering properties, which are related to its atomic thickness and unique electron, phonon structures. A number of literatures have reported the roles of graphene in these hybrid structures, including as a fluorescence quencher, molecule stabilizer and absorber, additional chemical enhancer, and oxidation preventer …”

Assessment of Ag Nanoparticles Interaction over Low-Cost Mesoporous Silica in Deep Desulfurization of Diesel

“…Smaller peaks at 369.0 and 375.0 eV are assigned to the typical BE region for Ag(0) nanoparticles highly dispersed in the support [30,41]. The presence of the metallic electronic state of silver may be related to the photolysis of the AgNO3 molecule in the presence of light; furthermore, it is known in the literature that some oxygenated metal-adsorbents can undergo autoreduction processes in the presence of lattice oxygen and water [42].…”