(Invited) Electrochemically Tuned Metamaterials: New Scenarios Navigated By Theory
Authors: Kornyshev Alexei A 
Published: February 2020

The notion of metamaterials has emerged in this century, primarily in the context of new structures with unusual optical properties, such as specially designed plasmonic materials. But metamaterials can be considered much more broadly, in the context of what is alternatively called smart materials, or even more modetly functional materials which can perform different kind of novel functions at our will.
N. Zheludev, opening a META-2014 congress in Singapore, made a provocative statement: “The time of metamaterials is over. It is the time of …tuneable metamaterials”. Electrochemistry, known to physicists as a “surface science with a joy stick — the potentiostat” (B.Ocko) is actually in a best position to deliver innovations on this front. It can be used to tune the properties of nano and micro- structures designed to be electrochemically controlled. In such structures, varying electrode potentials rearranges the ionic distributions, remarkably affecting system properties.
In this keynote I will discuss few most recent examples of electroactive/electrotuneable materials, the study of many of which are still in progress, and the design of which has been navigated or strongly influenced by the theory. These are

Electrovariable nanoplasmonic mirrors and trace analyte sensors [1-2].

Electrotuneable friction [3]

Ultrananoporous supercapacitors [4,5]

Electroactuators [6]

Reverse electroactuators — harvesters of mechanical energy, such as AC-current generating shoes [7]

Electrochemical single molecule rectifiers [8]

Looking pretty much applied, all this systems, however, rest on interesting physics, contain challenges for theory, themselves emerged as derivatives of knowledge that electrochemistry accumulated by now.
[1] J. Edel, A.A. Kornyshev, A. Kucernak, M. Urbakh, “Fundamentals and applications of self-assembled plasmonic nanoparticles at interfaces”, Chemical Soc. Reviews (2016) - DOI: 10.1039/c5cs00576k.
[2] J.B. Edel, A.A.Kornyshev, M.Urbakh. “Self-assembly of nanoparticle arrays for use as mirrors, sensors, and antennas”, ACS NANO, 7, 9526-9632 (2013).
[3] O. Fajardo, F. Bresme, A.A. Kornyshev, M. Urbakh, Electrotunable lubricity with ionic liquid nanoscale films,

Scientific Reports (NPG)
5
# 7698 (2015); “Electrotunable friction with ionic liquid lubricants: how important is the molecular structure of ions?” J.Phys.Chem.Lett.
6, 3998-4004 (2015).
[4] M.V.Fedorov, A.A.Kornyshev, Ionic liquids at electrified interfaces, Chem.Rev.
114, 2978−3036 (2014).
[5] S. Kondrat, A.A.Kornyshev, Pressing a spring: what does it take to maximize the energy storage in nanoporous supercapacitors? Nanoscael Horizons, B1, 45-52 (2016).
[6] A. Lee, R. Colby, A.A. Kornyshev, “Electroactuation with single charge carrier ionomers: the roles of electrostatic pressure and steric strain”, Soft Matter
9,3767-3776 (2013).
[7] A.B. Kolomeisky, A.A. Kornyshev, 2016, Current-generating 'double layer shoe' with a porous sole, J. Phys.Cond.Matter
28, ISSN: 0953-8984 (2016).
[8] K.C.M. Cheung, X. Chen, T.Albrecht, A. A. Kornyshev, “Principles of a single-molecule rectifier in electrolytic environment”,J.Phys.Chem.C (2016) - DOI: 10.1021/acs.jpcc.5b10320.