Ion Transport Research Articles

Fabrication of Polypyrrole Hollow Nanospheres by Hard-Template Method for Supercapacitor Electrode Material

Conducting polymers like polypyrrole, polyaniline, and polythiophene with nanostructures offers several advantages, such as high conductivity, a conjugated structure, and a large surface area, making them highly desirable for energy storage applications. However, the direct synthesis of conducting polymers with nanostructures poses a challenge. In this study, we employed a hard template method to fabricate polystyrene@polypyrrole (PS@PPy) core–shell nanoparticles. It is important to note that PS itself is a nonconductive material that hinders electron and ion transport, compromising the desired electrochemical properties. To overcome this limitation, the PS cores were removed using organic solvents to create hollow PPy nanospheres. We investigated six different organic solvents (cyclohexane, toluene, tetrahydrofuran, chloroform, acetone, and N,N-dimethylformamide (DMF)) for etching the PS cores. The resulting hollow PPy nanospheres showed various nanostructures, including intact, hollow, buckling, and collapsed structures, depending on the thickness of the PPy shell and the organic solvent used. PPy nanospheres synthesized with DMF demonstrated superior electrochemical properties compared to those prepared with other solvents, attributed to their highly effective PS removal efficiency, increased specific surface area, and improved charge transport efficiency. The specific capacitances of PPy nanospheres treated with DMF were as high as 350 F/g at 1 A/g. And the corresponding symmetric supercapacitor demonstrated a maximum energy density of 40 Wh/kg at a power density of 490 W/kg. These findings provide new insights into the synthesis method and energy storage mechanisms of PPy nanoparticles.

Erosion depth prediction of chloride ions under stray current using FEM based CNNs

Stray currents can accelerate the transport of corrosive ions, especially Cl−, in concrete materials, which is very detrimental to structural safety. Effectively predicting the erosion depth of Cl− is crucial for evaluating structural safety. This article is based on a finite element model and verifies the erosion depth of Cl− under different voltages, Cl− concentrations, and corrosion time through experimental data. A polynomial was used to fit the quantitative relationship between erosion depth, Cl− concentrations, and corrosion time under single voltage condition. However, this formula only applies to a single voltage and has too many parameters. Therefore, this article also established a CNNs regression model to predict the depth of Cl−, and the results showed the multiple regression ability of CNNs. It has been proven that CNNs can accurately predict the erosion depth, which helps to accurately evaluate structural safety. After comparing experimental values, CNNs, ResNet, and ResNet-attention, it was found that residual networks and attention mechanisms did not significantly improve the prediction accuracy of deep networks, which may be related to insufficient data volume. After expanding the dataset, ResNet performed the best overall, and ResNet-attention had better testing performance, which is related to the powerful feature extraction ability of the attention mechanism.

Unlocking dual-band electrochromism with stacked structure of amorphous tungsten oxide and Prussian blue

Dual-band electrochromic smart windows can selectively regulate the transmittance of visible and near-infrared (NIR) light, thereby significantly reducing energy consumption in buildings. However, the selective regulation for visible and NIR regions often relies on the integration of multiple components, together with meticulous design and fabrication. Herein, we propose the stacking of amorphous tungsten oxide (a-WO3) on the surface of Prussian blue (PB) through a straightforward magnetron sputtering deposition. Benefiting from the numerous voids-containing structures in the microstructure of a-WO3 films, the stacking structures are conducive to the insertion and transport of electrolyte ions, ensuring the electrochemical activity and electrochromic performance of the inner PB layer. The prepared PB/WO3 bilayer thin film can achieve three functionality modes in dual-band electrochromism: “bright”, “warm”, and “dark”, with high optical modulation of 74.9 % at 700 nm and 80.3 % at 1300 nm, respectively. Additionally, they demonstrate fast coloring/bleaching response (2.9/7.6 s at 700 nm and 6.0/6.2 s at 1300 nm) and satisfying cycling stability (retaining 95.3 % of its initial modulation after 500 cycles). The bilayer thin films based on amorphous electrochromic materials with an intrinsic abundance of voids-containing structures introduce a novel approach to the independent dual-band modulation for demanded light/thermal control.

Editorial: Novel therapeutic approach in cancer: the role of ion channels and transporters

Editorial: Novel therapeutic approach in cancer: the role of ion channels and transporters

Physiological and transcriptomic analyses reveal the cadmium tolerance mechanism of Miscanthus lutarioriparia.

Miscanthus lutarioriparia is a promising energy crop that is used for abandoned mine soil phytoremediation because of its high biomass yield and strong tolerance to heavy metals. However, the biological mechanism of heavy metal resistance is limited, especially for applications in the soil restoration of mining areas. Here, through the investigation of soil cadmium(Cd) in different mining areas and soil potted under Cd stress, the adsorption capacity of Miscanthus lutarioriparia was analyzed. The physiological and transcriptional effects of Cd stress on M. lutarioriparia leaves and roots under hydroponic conditions were analyzed. The results showed that M. lutarioriparia could reduce the Cd content in mining soil by 29.82%. Moreover, different Cd varieties have different Cd adsorption capacities in soils with higher Cd concentration. The highest cadmium concentrations in the aboveground and belowground parts of the plants were 185.65 mg/kg and 186.8 mg/kg, respectively. The total chlorophyll content, superoxide dismutase and catalase activities all showed a trend of increasing first and then decreasing. In total, 24,372 differentially expressed genes were obtained, including 7735 unique to leaves, 7725 unique to roots, and 8912 unique to leaves and roots, which showed differences in gene expression between leaves and roots. These genes were predominantly involved in plant hormone signal transduction, glutathione metabolism, flavonoid biosynthesis, ABC transporters, photosynthesis and the metal ion transport pathway. In addition, the number of upregulated genes was greater than the number of downregulated genes at different stress intervals, which indicated that M. lutarioriparia adapted to Cd stress mainly through positive regulation. These results lay a solid foundation for breeding excellent Cd resistant M. lutarioriparia and other plants. The results also have an important theoretical significance for further understanding the detoxification mechanism of Cd stress and the remediation of heavy metal pollution in mining soil.

Lithium‐Metal‐Free Sulfur Batteries with Biochar and Steam‐Activated Biochar‐Based Anodes from Spent Common Ivy

Lithium‐sulfur batteries are emerging as sustainable replacements for current lithium‐ion batteries. The commercial viability of this novel type of battery is still under debate due to the extensive use of highly reactive lithium‐metal anodes and the complex electrochemistry of the sulfur cathode. In this research, a novel sulfur‐based battery has been proposed that eliminates the need for metallic lithium anodes and other critical raw materials like cobalt and graphite, replacing them with biomass‐derived materials. This approach presents numerous benefits, encompassing ample availability, cost‐effectiveness, safety, and environmental friendliness. In particular, two types of biochar‐based anode electrodes (non‐activated and activated biochar) derived from spent common ivy have been investigated as alternatives to metallic lithium. We compared their structural and electrochemical properties, both of which exhibited good compatibility with the typical electrolytes used in sulfur batteries. Surprisingly, while steam activation results in an increased specific surface area, the non‐activated ivy biochar demonstrates better performance than the activated biochar, achieving a stable capacity of 400 mA h g−1 at 0.1 A g−1 and a long lifespan (>400 cycles at 0.5 A g−1). Our results demonstrate that the presence of heteroatoms, such as oxygen and nitrogen positively affects the capacity and cycling performance of the electrodes. This led to increased d‐spacing in the graphitic layer, a strong interaction with the solid electrolyte interphase layer, and improved ion transportation. Finally, the non‐activated biochar was successfully coupled with a sulfur cathode to fabricate lithium‐metal‐free sulfur batteries, delivering a specific energy density of ~600 Wh kg−1.

New insights into the photoassisted anodic reactions of n-type 4H SiC semiconductors

New insights into the photoassisted anodic reactions of n-type 4H SiC semiconductors

Ion and Molecular Sieving with Ultrathin Polydopamine Nanomembranes.

In contrast to biological cell membranes, it is still a major challenge for synthetic membranes to efficiently separate ions and small molecules, due to their similar sizes in the sub-nanometer range. Inspired by biological ion channels with their unique channel wall chemistry that facilitates ion sieving by ion-channel interactions, we report here the first free-standing, ultrathin (10-17nm) nanomembranes composed entirely of polydopamine (PDA) as ion and molecular sieves. These nanomembranes are obtained via an easily scalable electropolymerization strategy and provide nanochannels with various amine and phenolic hydroxyl groups that offer a favorable chemical environment for ion-channel electrostatic and hydrogen bond interactions. They exhibit remarkable selectivity for monovalent ions over multivalent ions and larger species with K+/Mg2+ of ≈4.2, K+/[Fe(CN)6]3- of ≈10.3, and K+/Rhodamine B of ≈273.0 in a pressure-driven process, as well as cyclic reversible pH-responsive gating properties. Infrared spectra reveal hydrogen bond formation between hydrated multivalent ions and PDA, which prevents the transport of multivalent ions and facilitates high selectivity. We propose chemically rich, free-standing, and pH-responsive PDA nanomembranes with specific interaction sites as customizable high-performance sieves for a wide range of challenging separation requirements. This article is protected by copyright. All rights reserved.

Enhancing ionic conductivity and controlling lithium dendrite growth via ferroelectric ceramic Bi4Ti3O12

BackgroundSolid polymer electrolytes (SPEs) have gained numerous research interest in the field of lithium metal batteries. Solid polymer electrolytes have improved safety compared to liquid electrolytes. Despite this, their low ionic conductivity remains a major barrier to practical applications. To overcome the challenge of low ionic conductivity in SPEs, our study introduces a novel approach that integrates ferroelectric ceramics with polymer solid electrolytes. MethodsWe used a one-step molten salt method to synthesize Bi4Ti3O12 (BIT), combined with a poly (vinylidene difluoride) matrix to form the composite solid-state electrolyte. Through various electrochemical characterizations and COMSOL Multiphysics simulations, we discovered that the ferroelectric properties of BIT significantly increase the dissociation of lithium salts, leading to a greater concentration of mobile lithium ions and more efficient ion transport. Significant findingsThis electrolyte showed a remarkable improvement in lithium-ion conductivity, reaching a value of 8.5 × 10−4 S cm−1 at room temperature. Batteries made with these composite electrolytes demonstrate superior cycling stability, the capacity retention rates for LFP/SPEs/Li cells remain high, reaching 95 % even after 1,000 cycles at room temperature (25 °C). These findings highlight the promising applications of ferroelectric ceramics in solid-state batteries.

Two-dimensional MXene/MOFs heterojunction nanosheets as confinement hosts for dendrite-free lithium metal anodes

Although metallic lithium is regarded as the most potential anode candidate for next-generation batteries, its applications are greatly restricted by the uncontrollable growth of lithium dendrites and unstable anode/electrolyte interface. Herein, MXene/MOFs heterojunction nanosheets are developed through a convenient self-assembly process by harnessing the chemical interactions between MXene and Ni-MOFs monolayers. In this heterojunction, not only the MXene interlayer induces uniform lithium nucleation, but also MOFs monolayers act as stable interfaces to promote Li ion transport and homogenize the subsequent lithium deposition. Moreover, the MXene/MOFs substrate mitigates the volume change of lithium anodes. Consequently, 2D MXene/MOFs heterojunction nanosheets as confinement hosts effectively suppress lithium dendrites and exhibit enhanced electrochemical performances including a coulombic efficiency of 99 % over 300 cycles at 0.5 mA cm−2 and 1 mAh cm−2, and a long cycling life up to 500 h at 1 mA cm−2 and 1 mAh cm−2. The MXene/MOFs-Li||LiFePO4 cells exhibit a stable cycling performance with a capacity retention of 91 % after 600 cycles.

Completely Methylene-Free Side Chain Enables Significant Microphase Separation at Medium IECs for Fuel-Cell Anion Exchange Membranes.

The introduction of hydrophobic side chain structures in anion exchange membranes (AEMs) to facilitate ion transport has been widely studied; however, low or moderate hydrophobic hydrocarbon and semifluorinated side chains are insufficient to induce a high degree of microphase separation. Herein, we design and prepare poly(aryl piperidinium) AEMs with completely methylene-free perfluorinated side chains, which can maximize the thermodynamic incompatibility between main- and side chains, thus enhancing microphase separation at medium ion exchange capacities (IECs). According to the molecular dynamics study, the methylene-free perfluorinated side chain leads to better hydration of cations. The hydroxide conductivity of the methylene-free perfluorinated side chain-grafted PAP-pF-1 membrane reaches 124.9 mS cm-1 at 80 °C, and the PAP-sF-1 with semifluorinated side chains and PAP-CH-1 with hydrocarbon side chains show lower conductivity (116.8 and 104.0 mS cm-1). The H2/O2 fuel cell using the PAP-pF-1 membrane demonstrates a remarkable peak power density (1651 mW cm-2 at 80 °C) and durability (greater than 300 h). This work provides a novel insight into enhancing microphase separation in AEMs; it opens up new possibilities for developing high-performance AEMs.

Strain Engineering of Ion-Coordinated Nanochannels in Nanocellulose.

Expanding the interlayer spacing plays a significant role in improving the conductivity of a cellulose-based conductor. However, it remains a challenge to regulate the cellulose nanochannel expanded by ion coordination. Herein, starting from multiscale mechanics, we proposed a strain engineering method to regulate the interlayer spacing of the cellulose nanochannels. First-principles calculations were conducted to select the most suitable ions for coordination. Large-scale molecular dynamics simulations were performed to reveal the mechanism of interlayer spacing expansion by the ion cross-linking. Combining the shear-lag model, we established the relationship between interfacial cross-link density and interlayer spacing of an ion-coordinated cellulose nanochannel. Consequently, fast ion transport and current regulation were realized via the strain engineering of nanochannels, which provides a promising strategy for the current regulation of a cellulose-based conductor.

Elastic scattering cross sections and transport of tin ions in extreme ultraviolet lithography sources

Abstract Energetic tin ions are created by laser produced plasmas in extreme-ultraviolet lithography sources where hydrogen is used as a buffer gas. In this study, the quantum chemistry code NWChem is used to calculate the interatomic potential between singly ionized tin and molecular hydrogen. The interatomic potential was fit by an inverse-power potential, a modified universal ZBL potential, and a two-piece-Lennard-Jones potential which were in turn used to calculate the classical distance of closest approach, scattering angle, total elastic scattering cross sections. Furthermore, the universal Ziegler-Biersack-Littmark (ZBL) potential was used in the open-source binary collision approximation codes RustBCA as well as Stopping Range in Matter and Transport of Ion in Matter (SRIM/TRIM) to calculate ion ranges, straggling, and stopping cross sections in a hydrogen gas target.

Self‐Healing Magnetic Field‐Assisted Threshold Switching Device Utilizing Dual Field‐Driven Filamentary Physics

AbstractAdvanced filamentary devices are crucial for developing low‐power devices to implement high‐speed logic and neuromorphic devices. Among these, HfO2‐based filamentary devices have attracted attention as viable options due to their threshold‐switching characteristics and compatibility with complementary metal‐oxide‐semiconductor (CMOS) technology. However, the unpredictability of conventional filament formation/rupture driven by an electric field challenges consistency and reliability. A paradigm shift from conventional stochastic electric field‐driven ion migration to controllable ion‐based transportation is essential to devise functional low‐power devices capable of controlling the filament process. This work introduces a magnetic field‐assisted threshold switching (MA‐TS) device, which integrates a neodymium magnet and a nickel (Ni) barrier layer to enable controlled dual field‐driven ion transportation. The dual field‐driven process combining the conventional vertical electric field‐driven ion migration with lateral magnetic field‐driven ion transportation, reveals a distinctive aspect of ion movement. The MA‐TS device achieves superior performances characterized by an ultra‐low threshold voltage (≈0 V), minimized leakage current in the off‐state, a variation‐immune hysteresis‐free characteristic, enhanced yield, and revival‐ability (i.e., self‐healing) after a failed TS operation. By overcoming the limitations of conventional filamentary devices, the MA‐TS device opens up a promising avenue for efficient and stable low‐power applications.

Molecular Insights into the Effect of Cholesterol on the Binding of Bicarbonate Ions in Band 3 Protein.

Band 3, or anion exchanger 1 (AE1), is one of the indispensable transmembrane proteins involved in the effective respiratory process of the human body and is primarily responsible for the exchange of bicarbonate and chloride anions across the plasma membrane of erythrocyte. However, the molecular mechanism of ion transport of Band 3 is not completely understood, yet. In this work, we systematically investigate the key binding sites of bicarbonate ions in Band 3 and the impact of cholesterol (CHOL) in lipid bilayers on bicarbonate ion binding using all-atom molecular dynamics (MD) simulations. We examine the dynamics of interactions of bicarbonate ions with Band 3 in the microsecond time scale and calculate the binding free energy of the anion in Band 3. The results indicate that the residue R730 of Band 3 is the most probable binding site for bicarbonate ions. CHOL enhances the bicarbonate ion binding by influencing the conformational stability of Band 3 and compressing the volume of the Band 3 cavity. These findings provide some insights into the bicarbonate ion binding in Band 3 and are helpful for understanding the anion exchange of Band 3.

Endocrine control of gill ionocyte function in euryhaline fishes.

The endocrine system is an essential regulator of the osmoregulatory organs that enable euryhaline fishes to maintain hydromineral balance in a broad range of environmental salinities. Because branchial ionocytes are the primary site for the active exchange of Na+, Cl-, and Ca2+ with the external environment, their functional regulation is inextricably linked with adaptive responses to changes in salinity. Here, we review the molecular-level processes that connect osmoregulatory hormones with branchial ion transport. We focus on how factors such as prolactin, growth hormone, cortisol, and insulin-like growth-factors operate through their cognate receptors to direct the expression of specific ion transporters/channels, Na+/K+-ATPases, tight-junction proteins, and aquaporins in ion-absorptive (freshwater-type) and ion-secretory (seawater-type) ionocytes. While these connections have historically been deduced in teleost models, more recently, increased attention has been given to understanding the nature of these connections in basal lineages. We conclude our review by proposing areas for future investigation that aim to fill gaps in the collective understanding of how hormonal signaling underlies ionocyte-based processes.

The biophysics of water in cell biology: perspectives on a keystone for both marine sciences and cancer research

The biophysics of water, has been debated over more than a century. Although its importance is still underestimated, significant breakthroughs occurred in recent years. The influence of protein condensation on water availability control was documented, new findings on water-transport proteins emerged, and the way water molecules rearrange to minimize free energy at interfaces was deciphered, influencing membrane thermodynamics. The state of knowledge continued to progress in the field of deep-sea marine biology, highlighting unknown effects of high hydrostatic pressure and/or temperature on interactions between proteins and ligands in extreme environments, and membrane structure adaptations. The role of osmolytes in protein stability control under stress is also discussed here in relation to fish egg hydration/buoyancy. The complexity of water movements within the cell is updated, all these findings leading to a better view of their impact on many cellular processes. The way water flow and osmotic gradients generated by ion transport work together to produce the driving force behind cell migration is also relevant to both marine biology and cancer research. Additional common points concern water dynamic changes during the neoplastic transformation of cells and tissues, or embryo development. This could improve imaging techniques, early cancer diagnosis, and understanding of the molecular and physiological basis of buoyancy for many marine species.

Interfacial Super‐Assembly of Vacancy Engineered Ultrathin‐Nanosheets toward Nanochannels for Smart Ion Transport and Salinity Gradient Power Conversion

Ion‐selective nanochannel membranes assembled from two‐dimensional (2D) nanosheets hold immense promise for power conversion using salinity gradient. However, they face challenges stemming from insufficient surface charge density, which impairs both permselectivity and durability. Herein, we present a novel vacancy‐engineered, oxygen‐deficient NiCo layered double hydroxide (NiCoLDH)/cellulose nanofibers‐wrapped carbon nanotubes (VOLDH/CNF‐CNT) composite membrane. This membrane, featuring abundant angstrom‐scale, cation‐selective nanochannels, is designed and fabricated through a synergistic combination of vacancy engineering and interfacial super‐assembly. The membrane shows interlayer free‐spacing of ~3.62 Å, which validates the membrane size exclusion selectivity.This strategy, validated by DFT calculations and experimental data, improves hydrophilicity and surface charge density, leading to the strong interaction with K+ ions to benefit the low ion transport resistance and exceptional charge selectivity. When employed in an artificial river water|seawater salinity gradient power generator, it delivers a high‐power density of 5.35 W/m2 with long‐term durability (20,000s), which is almost 400% higher than that of the pristine NiCoLDH membrane. Furthermore, it displays both pH‐ and temperature‐sensitive ion transport behavior, offering additional opportunities for optimization. This work establishes a basis for high‐performance salinity gradient power conversion and underscores the potential of vacancy engineering and super‐assembly in customizing 2D nanomaterials for diverse advanced nanofluidic energy devices.

Interfacial Super-Assembly of Vacancy Engineered Ultrathin-Nanosheets toward Nanochannels for Smart Ion Transport and Salinity Gradient Power Conversion.

Ion-selective nanochannel membranes assembled from two-dimensional (2D) nanosheets hold immense promise for power conversion using salinity gradient. However, they face challenges stemming from insufficient surface charge density, which impairs both permselectivity and durability. Herein, we present a novel vacancy-engineered, oxygen-deficient NiCo layered double hydroxide (NiCoLDH)/cellulose nanofibers-wrapped carbon nanotubes (VOLDH/CNF-CNT) composite membrane. This membrane, featuring abundant angstrom-scale, cation-selective nanochannels, is designed and fabricated through a synergistic combination of vacancy engineering and interfacial super-assembly. The membrane shows interlayer free-spacing of ~3.62 Å, which validates the membrane size exclusion selectivity.This strategy, validated by DFT calculations and experimental data, improves hydrophilicity and surface charge density, leading to the strong interaction with K+ ions to benefit the low ion transport resistance and exceptional charge selectivity. When employed in an artificial river water|seawater salinity gradient power generator, it delivers a high-power density of 5.35 W/m2 with long-term durability (20,000s), which is almost 400% higher than that of the pristine NiCoLDH membrane. Furthermore, it displays both pH- and temperature-sensitive ion transport behavior, offering additional opportunities for optimization. This work establishes a basis for high-performance salinity gradient power conversion and underscores the potential of vacancy engineering and super-assembly in customizing 2D nanomaterials for diverse advanced nanofluidic energy devices.

Dealloyed nickel skeleton hosting in-situ formed multimetallic phosphides for enhanced electrochemical energy storage

Transition metal phosphides (TMPs) exhibit considerable potential in supercapacitors (SCs) electrodes fabrication due to their high power densities and conducive ion transport, positioning them as quintessential candidates for such application. Despite their promise, monometallic phosphides require further electrochemical performance enhancements. This work unveils an innovative strategy for synthesizing complex cobalt/nickel phosphides directly on a nickel skeleton (Ni@NCP), achieved by the selectively leaching copper from a Ni–Cu alloy via a dealloying process after electrodeposition, significantly improving electrochemical performance through increased electroactive sites and optimized ion diffusion channels. The Ni@NCP electrode exhibits an impressive specific capacitance of 612 F g−1 at a high current density of 20 A g−1. Furthermore, the unique hollow nanotube structure greatly enhances cyclic stability, maintaining 80.1 % capacity after 10,000 cycles at 10 A g−1. This research presents a methodical approach to electrode material synthesis, emphasizing the construction of supportive frameworks and active sites, thereby underscoring the substantial potential for advancements in SC electrode technology.