Nanoporous gold nanoleaf as tunable metamaterial

Abstract

We have studied optical properties of single-layer and multi-fold nanoporous gold leaf (NPGL) metamaterials and observed highly unusual transmission spectra composed of two well-resolved peaks. We explain this phenomenon in terms of a surface plasmon absorption band positioned on the top of a broader transmission band, the latter being characteristic of both homogeneous “solid” and inhomogeneous “diluted” Au films. The transmission spectra of NPGL metamaterials were shown to be controlled by external dielectric environments, e.g. water and applied voltage in an electrochemical cell. This paves the road to numerous functionalities of the studied tunable and active metamaterials, including control of spontaneous emission, energy transfer and many others.

Nanoporous Gold: From Structure Evolution to Functional Properties in Catalysis and Electrochemistry

“…In principle, NPG can be prepared in every shape and dimension, as long as the precursor alloy and a surrounding electrolyte share a common interface. Geometries range from nanoscale particles, wires, films, − and leaves ,,− to μm-thick coatings, pillars, , and sheets, − up to mm- ,,,− or cm-size bulk samples. The making of even larger parts from NPG, for instance in the form of macroscale scaffolds for catalysis, has been demonstrated based on 3D printing …”

“…Dealloying can be prompted by free ,,,,− or by electrochemically ,,,,,,,, controlled corrosion. Electrolytes include aqueous solutions across the whole pH range ,,,,, as well as ionic liquids. ,, However, the majority of preparation protocols for NPG use acidic environments.…”

“…Electrolytes include aqueous solutions across the whole pH range ,,,,, as well as ionic liquids. ,, However, the majority of preparation protocols for NPG use acidic environments. For Au–Ag master alloys, free corrosion is generally carried out by concentrated HNO 3 , ,,,,− while electrochemical dealloying typically uses dilute HClO 4 solutions. ,,,,, Both free and electrochemical dealloying can produce large monolithic volumes of NPG with comparable microstructure . For samples with identical L and master alloy composition, similar mechanical properties are observed irrespective of which corrosion method is used. , This suggests comparable sample quality and comparable microstructure.…”

Probing Charge Transport Kinetics in a Plasmonic Environment with Cyclic Voltammetry

“…Plasmonic metamaterials and metasurfaces can provide unprecedented control of light − and bring new possibilities for modifying and controlling various physical and chemical phenomena. The range of such phenomena is very broad, including strong modifications in the spontaneous emission rate and spectrum, − change in the Förster energy transfer rate, , modification of van der Waals forces, and new or accelerated chemical reactions − in the vicinity of plasmonic structures, metasurfaces, and metamaterials.…”

Review of Metasurfaces and Metadevices: Advantages of Different Materials and Fabrications

“…Plasmonic gap resonators integrated with active materials (e.g., semiconductors) are available to form electrically tunable metasurfaces, which have attracted considerable interest in recent years [104][105][106][107][108][109]. In 2021, Park et al fabricated a three-dimensional (3D) LiDAR device based on an active metasurface composed of a gold nanoantenna array with electrically tunable channels, as illustrated in Figure 2d [110].…”