On the voltage-controlled assembly of nanoparticle arrays at electrochemical solid/liquid interfaces

Zagar, Cristian; Griffiths, Ryan‐Rhys; Podgornik, Rudolf; Kornyshev, Alexei A.

doi:10.1016/j.jelechem.2020.114275

Cited by 3 publications

(3 citation statements)

References 34 publications

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“…At positive electrode potentials, negatively charged NPs get electrosorbed at the electrode, but as they electrostatically repel each other, they prefer not to come close to each other. With further increase of the positive potential, the driving force for each NPs to be adsorbed at the interface gets stronger, and more NPs adsorb at the electrode, tolerating interparticle repulsion, and hence the NP-array gets denser . The results of fitting the theoretical reflectance spectra to the experimental ones (Figure d) with the average inter NP distance as the fitting parameter indicates that this distance starts from several hundreds of nm at 0.1 V vs PZC, and quickly reduces to 20 nm at 0.7 V vs PZC.…”

Section: Resultsmentioning

confidence: 95%

Electrotunable Nanoplasmonics for Amplified Surface Enhanced Raman Spectroscopy

Sikdar

Fedosyuk

et al. 2019

ACS Nano

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Tuning the properties of optical metamaterials in real time is one of the grand challenges of photonics. Being able to do so will enable a class of adaptive photonic materials for use in applications such as surface enhanced Raman spectroscopy and reflectors/absorbers. One strategy to achieving this goal is based on the electrovariable self-assembly and disassembly of two-dimensional nanoparticle arrays at a metal | liquid interface. As expected, the structure results in plasmonic coupling between NPs in the array but perhaps as importantly between the array and the metal surface. In such a system, the density of the nanoparticle array can be reversibly controlled by the variation of electrode potential. Theory suggests that due to a collective plasmon-coupling effect less than 1 V variation of electrode potential can give rise to a dramatic simultaneous change in optical reflectivity from ∼93% to ∼1% and the amplification of the SERS signal by up to 5 orders of magnitude. This is experimentally demonstrated using a platform based on the voltage-controlled assembly of 40 nm Au-nanoparticle arrays at a TiN/Ag electrode in contact with an aqueous electrolyte. We show that all the physics underpinning the behavior of this platform works precisely as suggested by the proposed theory, setting the electrochemical nanoplasmonics as a promising direction in photonics research.

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Section: Resultsmentioning

confidence: 95%

Electrotunable Nanoplasmonics for Amplified Surface Enhanced Raman Spectroscopy

Sikdar

Fedosyuk

et al. 2019

ACS Nano

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“…The derivation of the equations below are presented in ref , so here we will just give a brief summary of them and the physics behind them. From an electrostatic viewpoint, the two phases (electrolyte-I and electrode-II) are characterized by their dielectric properties and ability to screen electric fields.…”

Section: Methodsmentioning

confidence: 99%

“…They are used to plot the curves in Figure D. In ref , the detailed analysis of the contribution of the corresponding van der Waals interactions is also performed, and they are found to give a smaller contribution. The analysis of the effects of electronic polarizability of NPs were not performed, but those are believed to be much smaller than direct and image interactions for particles that are highly charged by MDDA ligands.…”

Section: Methodsmentioning

confidence: 99%

A Tunable Nanoplasmonic Mirror at an Electrochemical Interface

Zagar

Klemme

et al. 2018

ACS Photonics

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Designing tunable optical metamaterials is one of the great challenges in photonics. Strategies for reversible tuning of nanoengineered devices are currently being sought through electromagnetic or piezo effects. For example, bottom-up self-assembly of nanoparticles at solid | liquid or liquid | liquid interfaces can be used to tune optical responses by varying their structure either chemically or through applied voltage. Here, we report on a fully reversible tunable-color mirror based on a TiN-coated Ag substrate immersed in an aqueous solution of negatively charged Au-nanoparticles (NPs). Switching electrode potential can be used to fully control the assembly/disassembly of NPs at the electrode | electrolyte interface within a 0.6 V wide electrochemical window. The plasmon coupling between the electrode and the adsorbed NP array at high positive potentials produces a dip in the optical reflectance spectrum, creating the “absorber” state. Desorption of NPs at low potentials eliminates the dip, returning the system to the reflective “mirror” state. The intensity and wavelength of the dip can be finely tuned through electrode-potential and electrolyte concentration. The excellent match between the experimental data and the theory of optical response for such system allows us to extract valuable information on equilibrium and kinetic properties of NP-assembly/disassembly. Together with modeling of the latter, this study promotes optimization of such meta-surfaces for building electrotunable reflector devices.

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Influence of image forces on charge–dipole interaction in two-layered systems

Gabovich,

Gorshkov,

Semeniuk

et al. 2024

The Journal of Chemical Physics

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Interaction between a fixed point electric charge Q and a freely rotating point electric dipole with the magnitude P pinned near a plane interface between two dispersionless insulators with different dielectric permittivities ɛ1 and ɛ2 has been considered. It was shown that, as a result of this interaction and the interaction of the dipole with the polarization charges induced at the interface by the charge Q and the dipole itself, there arise regions where the dipole can possess either one or two equilibrium orientations. The spatial distributions of the electrostatic dipole energy Wtotal under the combined action of the charge Q and the induced interface polarization charges, as well as the equilibrium dipole orientations (orientation maps), the boundaries between the regions with different numbers of dipole orientations, and their evolution with the variation of problem parameters (the charge and dipole magnitudes, the mismatch between ɛ1 and ɛ2, and the charge–interface distance) were calculated. It was shown that there can emerge local minima of Wtotal, which may play the role of traps for dipoles (in particular, excitons in layered structures), and the corresponding requirements for the problem parameters were found. Most results were obtained in analytical form. The model can be applied to various physical systems, for instance, polar molecules, excitons, and trions in layered structures.

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On the voltage-controlled assembly of nanoparticle arrays at electrochemical solid/liquid interfaces

Cited by 3 publications

References 34 publications

Electrotunable Nanoplasmonics for Amplified Surface Enhanced Raman Spectroscopy

Electrotunable Nanoplasmonics for Amplified Surface Enhanced Raman Spectroscopy

A Tunable Nanoplasmonic Mirror at an Electrochemical Interface

Influence of image forces on charge–dipole interaction in two-layered systems

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