Themed collection Iontronics: from fundamentals to ion-controlled devices

The Scientific Committee, from left to right: Professors Susan Perkin, Monica Olvera de la Cruz, Serge G. Lemay, René van Roij and Sanli Faez.

We briefly review theoretical, experimental and simulation results on screening in concentrated electrolytes and study the effect of solvent and confinement on structure and screening behaviour using classical DFT combined with atomistic simulations.

The electrical response and asymmetric ion transport affected the transport of low-abundance molecules across the diode. Integration of multiple diodes enabled implementation of an OR logic operation on both the voltage and the molecule transport.

Droplet spreading upon compression enlarges the contact area between the electrodes and electrolyte, increasing the double-layer capacitance, which generates a transient ionic current in solution and an electronic current in the circuit.

Is this the dawn of iontronics? Iontronics underpins the notion of devices and ionic machines, whereby ion and water also act as information carriers. Thinking about iontronics gives a vision and a road map, with applications in the water–energy nexus.

We follow the evolution of the electrical double layer of colloidal SiO₂ particles from the micromolar to the millimolar regime using nonlinear optical techniques and evidence a diffuse layer compression.

We quantitatively explain the diodic and memristive properties of conical ion channels with bipolar surface charges. A modelled iontronic circuit of these channels exhibits neuronal spiking with membrane potentials comparable to mammalian values.

A general theory of coupled ion–electron transfer (CIET) is presented, which unifies Marcus kinetics of electron transfer (ET) with Butler–Volmer kinetics of ion transfer (IT).

This paper explores the dynamics of particles in a viscosity gradient with numerical simulations.

We present a classical density functional theory based on the hypernetted-chain approximation, which allows us to calculate the velocity of electroosmotic flows inside nanopores containing 1 : 1 or 2 : 1 electrolyte solution.

Nanofluidic channels with a bio-inspired polydopamine and poly-L-lysine coating exhibit significant diodicity and are capable of exceeding 1000-fold current rectification under certain conditions.

We investigated the impact of two semi-solid gel electrolytes, iongel and organogel, with different ionic conductivities on the performance of printed planar and vertical organic electrochemical transistors (OECTs).

We apply EDL-modulation microscopy to one of the main components of amperometric measurement devices: a microelectrode.

We explore in real-time transport of ionic species (LiClO₄) confined between a negatively charged mica and an electrochemically modulated gold surface using Surface Force Apparatus, molecular dynamics simulations and continuum-based Stern model.

Electrowetting on graphene substrates is studied as a function of electrolyte identity and graphene layer number; the response observed is contrasted with that seen on the bulk material (graphite).

Nonlinear spectroscopy and electrokinetic measurements reveal that the electrochemical properties of a solid–liquid interface in salt solutions in propylene carbonate are dependent on the solvent chirality.

A systematic study using dynamic Atomic Force Microscopy of hydration forces on mica surfaces and amorphous silica surfaces in aqueous electrolytes containing chloride salts of various alkali and earth alkaline cations of variable concentrations.

Nanochannels made of conductors enhance ion transport due to the screening of electrostatic interactions by the induced polarization.

1/f noise is intrinsic to ion transport; deviations to it allow probing of the dynamics of confined systems.

A recently developed, new ionic device called the ionic voltage effect soft triode (IVEST) was optimized, tuned and embedded into a memory application concept.

Electrocatalysis at an isolated nanoparticle induces the growth of an electrolyte nanodroplet by ion pumping across a nanochannel.

Periodic dynamic operation promotes CO faradaic efficiency. The key promoting parameters are the charge transfer coefficients of parallel reactions.

Ionic fluctuations in finite observation volumes exhibit fractional noise features and hyperuniformity with time, improving our understanding of single-particle electrochemistry.

We present direct measurements of the interaction force as a function of separation distance, measured using a surface force balance, across solutions of a protic ionic liquid ethylammonium nitrate and its mixtures with water.

We highlight the central role of the charge–charge dynamic structure factor in the fluctuations of electrical observables in electrolytes and offer a unifying perspective over a variety of complementary experiments.

A multifrequency approach based on high-resolution atomic force microscopy in liquid is developed to map the dielectric properties of solid–electrolyte interfaces with nanoscale resolution.