Graphene-Enabled Silver Nanoantenna Sensors

Abstract

Silver is the ideal material for plasmonics because of its low loss at optical frequencies but is often replaced by a more lossy metal, gold. This is because of silver's tendency to tarnish and roughen, forming Ag(2)S on its surface, dramatically diminishing optical properties and rendering it unreliable for applications. By passivating the surface of silver nanostructures with monolayer graphene, atmospheric sulfur containing compounds are unable to penetrate the graphene to degrade the surface of the silver. Preventing this sulfidation eliminates the increased material damping and scattering losses originating from the unintentional Ag(2)S layer. Because it is atomically thin, graphene does not interfere with the ability of localized surface plasmons to interact with the environment in sensing applications. Furthermore, after 30 days graphene-passivated silver (Ag-Gr) nanoantennas exhibit a 2600% higher sensitivity over that of bare Ag nanoantennas and 2 orders of magnitude improvement in peak width endurance. By employing graphene in this manner, the excellent optical properties and large spectral range of silver can be functionally utilized in a variety of nanoscale plasmonic devices and applications.

The rectenna device: From theory to practice (a review)

“…The recent development of graphene technology also prompts the incorporation of graphene into nanoantenna design. Ag is known to suffer from sulfidation under ambient environment, resulting in degradation of the plasmonic property 136 . Graphene was shown to be able to passivate the Ag and prevent sulfidation without affecting the plasmonic property of the Ag nanoantenna 136 .…”

“…Ag is known to suffer from sulfidation under ambient environment, resulting in degradation of the plasmonic property 136 . Graphene was shown to be able to passivate the Ag and prevent sulfidation without affecting the plasmonic property of the Ag nanoantenna 136 . Additionally, radical changes in the plasmon energy and strength were also observed by electrically doping patterned graphene arrays with a gate voltage 137 .…”

Permittivity evaluation of multilayered hyperbolic metamaterials: Ellipsometry vs. reflectometry

“…Alternatively, recent results demonstrated that graphene layers can serve as an excellent protection against tarnishing of Ag-based plasmonic structures. 24 In comparing reflectance-based vs. ellipsometer-based parameter extraction, we find that in-plane permittivity results show excellent agreement between the two methods, while out-of-plane permittivity results do not agree as well, especially for the real part of the permittivity. The discrepancy may be based on experimental challenges of measuring out-of-plane permittivity.…”

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

“…However, the chemically inert, 1G-covered Ag nanoantennas did not show signs of changes; the surfaces of the particles kept their triangle shape, as shown in Figure 1e. In a previous study, by passivating the surface of silver nanostructures with 1G, atmospheric sulfur-containing compounds (hydrogen sulfide (H 2 S) and carbonyl sulfide) were unable to degrade the surface of the silver 33 . The ABNA is protected by the graphene monolayer.…”