A New Strategy for Highly Efficient Separation between Monovalent Cations by Applying Opposite-Oriented Pressure and Electric Fields.

Biological ion channels exhibit excellent ion selectivity, but it has been challenging to design their artificial counterparts, especially for highly efficient separation of similar ions. Here, a new strategy to achieve high selectivity between alkali metal ions with artificial nanostructures is reported. Molecular dynamics (MD) simulations and experiments are combined to study the transportation of monovalent cations through graphene oxide (GO) nanoslits by applying pressure or/and electric fields.

The Optimization of the Transition Zone of the Planar Heterogeneous Interface for High-Performance Seawater Desalination.

Reverse osmosis has become the most prevalent approach to seawater desalination. It is still limited by the permeability-selectivity trade-off of the membranes and the energy consumption in the operation process. Recently, an efficient ionic sieving with high performance was realized by utilizing the bi-unipolar transport behaviour and strong ion depletion of heterogeneous structures in 2D materials.

The Selective Transport of Ions in Charged Nanopore with Combined Multi-Physics Fields.

The selective transport of ions in nanopores attracts broad interest due to their potential applications in chemical separation, ion filtration, seawater desalination, and energy conversion. The ion selectivity based on the ion dehydration and steric hindrance is still limited by the very similar diameter between different hydrated ions. The selectivity can only separate specific ion species, lacking a general separation effect.

Harnessing Ionic Power from Equilibrium Electrolyte Solution via Photoinduced Active Ion Transport through van-der-Waals-Like Heterostructures.

Nanofluidic ion transport through van der Waals heterostructures, composed of two or more types of reconstructed 2D nanomaterials, gives rise to fascinating opportunities for light-energy harvesting, due to coupling between the optoelectronic properties of the layered constituents and ion transport in between the atomic layers. Here, a photoinduced active ion transport phenomenon through transition metal dichalcogenides (TMDs)-based van-der-Waals-like multilayer heterostructures is reported for harnessing ionic power from equilibrium electrolyte solution. The binary heterostructure comprises sequentially stacked 2D-WS and 2D-MoS multilayers with sub-1 nm interlayer spacing.

Vertically-Oriented TiCT MXene Membranes for High Performance of Electrokinetic Energy Conversion.

The electrokinetic effect to convert the mechanical energy from ambient has gained sustained research attention because it is free of moving parts and easy to be miniaturized for microscale applications. The practical application is constrained by the limited electrokinetic energy conversion performance. Herein, we report vertically oriented MXene membranes (VMMs) with ultrafast permeation as well as high ion selectivity, in which the permeation is several thousand higher than the largely researched horizontally stacked MXene membranes (HMMs).

Vertically Transported Graphene Oxide for High-Performance Osmotic Energy Conversion.

Reverse electrodialysis is a promising method to harvest the osmotic energy stored between seawater and freshwater, but it has been a long-standing challenge to fabricate permselective membranes with the power density surpassing the industry benchmark of 5.0 W m for half a century. Herein, a vertically transported graphene oxide (V-GO) with the combination of high ion selectivity and ultrafast ion permeation is reported, whose permeation is three orders of magnitude higher than the extensively studied horizontally transported GO (H-GO).

Electric-Field-Induced Ionic Sieving at Planar Graphene Oxide Heterojunctions for Miniaturized Water Desalination.

Layered graphene oxide membranes (GOMs) offer a unique platform for precise sieving of small ions and molecules due to controlled sub-nanometer-wide interlayer distance and versatile surface chemistry. Pristine and chemically modified GOMs effectively block organic dyes and nanoparticles, but fail to exclude smaller ions with hydrated diameters less than 9 Å. Toward sieving of small inorganic salt ions, a number of strategies are proposed by reducing the interlayer spacing down to merely several angstroms.

The development of a hydrogen-helium dual-beam ion implanter.

Multiple ion beam facilities are powerful tools to simulate the irradiation effects of neutrons on relevant nuclear materials. Since hydrogen and helium are often generated in neutron irradiated materials as transmutation products and they play important roles in the defect evolution, the triple beam accelerator and transmission electron microscope link in situ facility instead of a monobeam or dual-beam facility is necessary to simulate neutron irradiation. A hydrogen-helium dual-beam ion implanter has been developed for a triple ion beam in situ facility at Xiamen University.

On the Origin of Ionic Rectification in DNA-Stuffed Nanopores: The Breaking and Retrieving Symmetry.

The discovery of ionic current rectification (ICR) phenomena in synthetic nanofluidic systems elicits broad interest from interdisciplinary fields of chemistry, physics, materials science, and nanotechnology; and thus, boosts their applications in, for example, chemical sensing, fluidic pumping, and energy related aspects. So far, it is generally accepted that the ICR effect stems from the broken symmetry either in the nanofluidic structures, or in the environmental conditions. Although this empirical regularity is supported by numerous experimental and theoretical results, great challenge still remains to precisely figure out the correlation between the asymmetric ion transport properties and the degree of symmetry breaking.

Concentration-gradient-dependent ion current rectification in charged conical nanopores.

Ion current rectification (ICR) in negatively charged conical nanopores is shown to be controlled by the electrolyte concentration gradient depending on the direction of ion diffusion. The degree of ICR is enhanced with the increasing forward concentration difference. An unusual rectification inversion is observed when the concentration gradient is reversely applied.

Current rectification in temperature-responsive single nanopores.

Herein we demonstrate a fully abiotic smart single-nanopore device that rectifies ionic current in response to the temperature. The temperature-responsive nanopore ionic rectifier can be switched between a rectifying state below 34 degrees C and a non-rectifying state above 38 degrees C actuated by the phase transition of the poly(N-isopropylacrylamide) [PNIPAM] brushes. On the rectifying state, the rectifying efficiency can be enhanced by the dehydration of the attached PNIPAM brushes below the LCST.

A biomimetic potassium responsive nanochannel: G-quadruplex DNA conformational switching in a synthetic nanopore.

Potassium is especially crucial in modulating the activity of muscles and nerves whose cells have specialized ion channels for transporting potassium. Normal body function extremely depends on the regulation of potassium concentrations inside the ion channels within a certain range. For life science, undoubtedly, it is significant and challenging to study and imitate these processes happening in living organisms with a convenient artificial system.