Ion Diode Research Articles

Achieving "Ion Diode" Salt Resistance in Solar Interfacial Evaporation by a Tesla Valve-Like Water Transport Structure.

Salt deposition is a disturbing problem that limits the development of passive solar-driven interfacial evaporation. Inspired by the passive fluid control mechanism of the Tesla valve, a novel solar evaporator is proposed with a Tesla valve-like water transport structure to prevent salt accumulation at the evaporation interface. A unique "ion diode" salt resistance of this evaporator is significantly achieved by optimizing the two asymmetric water transport structures, consisting of one Tesla valve-like side and one wide-leg side, which establish a reverse-suppressing and forward-accelerating water transport channel. In contrast to the limited ion migration of the typical symmetric solar evaporator, such a channel caused by the water/salt ions transport difference between two water supply structures, reinforces the water/salt ions supply on the wide-leg side, thus leading to an apparent unidirectional salt ions migration from the wide-leg side to bulk water through the Tesla valve-like side. Consequently, an evaporation rate of 3.25kg m-2h-1 and a conversion efficiency of 83.27% under 2suns are achieved in 16wt% NaCl solution. The development of the Tesla Valve-like evaporator provides a new perspective for solving salt deposition and realizing scalable applications of solar-driven interfacial evaporation.

Spoke-Type Structures in an Ion Diode with Magnetic Insulation of Electrons

The article presents the results concerning the cross-sectional energy density distribution of a pulsed ion beam for two types of diodes with electron open drift: with external magnetic insulation (250 kV, 80 ns, 0.6 T) and with self-magnetic insulation of electrons (250–300 kV, 120 ns, 0.8 T). Anode plasma is formed using a breakdown along the surface of the anode dielectric coating (single-pulse mode) or explosive electron emission (with double opposite-polarity pulses). It was found that, when the energy density of the ion beam exceeds ≈0.4 J/cm2, periodic spoke-type structures with a step of 3–6 cm in the beam cross section are formed. The processes of formation of such a structure—nonuniform density of anode plasma and self-organization of anode and/or cathode plasma in crossed electric and magnetic fields—are analyzed. It is shown that the formation of local plasma regions in the anode–cathode gap of an ion diode can cause the formation of a periodic structure of the cross-sectional energy density distribution.

Self-Supplying Photovoltaic-Hygroelectric Coupling System Powering Internet of Things Sensors.

The rapid advancement in the Internet of Things (IoT) has prompted a proliferation of sensor applications with increasing focus on harnessing environmental energy sources for powering these sensors. However, owing to the variability inherent in climatic and geographic conditions, a singular approach to environmental energy harvesting often fails to deliver sustainable and reliable power. Hygroelectric technology, leveraging the electrical coupling between nanostructured materials and water to convert moisture-derived energy into electricity, complements the advantages of light energy collection technology. In this study, an ion diode moisture-based power generation array was fabricated to yield an open-circuit voltage of 8 V and a short-circuit current of 3 mA under an 86.9% relative humidity (RH). Subsequently, integration of a photovoltaic module with the hygroelectric generator assembly via an energy management circuit augmented the system's overall power generation, manifesting a remarkable 1150% increase over the original moisture-based power generation configuration. Furthermore, the incorporation of such a hybridized system bolstered the operational efficiency, extending the duration of continuous power supply cycles by up to 78.2% in comparison with the control group with no moisture-derived energy input. This pioneering endeavor unveils a novel light-moisture coupling energy-harvesting paradigm tailored for sustaining uninterrupted power provision in wireless sensor network nodes, and the harvesting of one energy source is not affected by the other energy source at all. With its inherent adaptability, this approach holds promise for deployment in outdoor environments characterized by low illumination levels and high humidity, presenting a versatile solution to address sensor powering challenges.

Modular Customized Biomimetic Nanofluidic Diode for Tunable Asymmetric Ion Transport.

Artificial ion diodes, inspired by biological ion channels, have made significant contributions to the fields of physics, chemistry, and biology. However, constructing asymmetric sub-nanofluidic membranes that simultaneously meet the requirements of easy fabrication, high ion transport efficiency, and tunable ion transport remains a challenge. Here, a direct and flexible in situ staged host-guest self-assembly strategy is employed to fabricate ion diode membranes capable of achieving zonal regulation. Coupling the interfacial polymerization process with a host-guest assembly strategy, it is possible to easily manipulate the type, order, thickness, and charge density of each module by introducing two oppositely charged modules in stages. This method enables the tuning of ion transport behavior over a wide range salinity, as well as responsive to varying pH levels. To verify the potential of controllable diode membranes for application, two ion diode membranes with different ion selectivity and high charge density are coupled in a reverse electrodialysis device. This resulted in an output power density of 63.7W m-2 at 50-fold NaCl concentration gradient, which is 12 times higher than commercial standards. This approach shows potential for expanding the variety of materials that are appropriate for microelectronic power generation devices, desalination, and biosensing.

Ion current rectification coupled with asymmetric temperature and surface charge in ultrashort conical nanopores

Ion current rectification (ICR) is one of the electrodynamic properties in asymmetric nanochannels, which has been utilized to develop biosensors, heavy metal ion detection, and ion diodes. Previous studies on ICR mainly focused on long nanopores (length >500 nm), and relatively few studies on ion rectification performance in short nanopores. Here, we use a finite element numerical solution to simulate the effect of coupling asymmetric temperature and surface charge distribution on the ion rectification performance of ultrashort conical nanopores (length = 100 nm). The results show that the ion rectification performance is significantly improved when the inner and outer surfaces of the nanopore are charged non-uniformly, which is more than three times that when the inner surface of the nanopore is charged non-uniformly or the outer surface is charged non-uniformly. In addition, the positive temperature difference enhances the ion enrichment and dissipation and improves the ion rectification performance of nanopores. On the contrary, negative temperature difference inhibits ion enrichment and dissipation in pores, which is not conducive to improving ion rectification performance. Abnormal behavior is observed for nanopores non-uniform charged only on the outer wall surface, where the negative temperature gradient enhances the accumulation and dissipation of ions within the pores, thereby increasing the rectification ratio. In addition, in order to more clearly understand the ion transport behavior in the ultrashort nanopore under asymmetric temperature conditions, we further investigated the influence of the tip radius of the nanopore, the solution volume concentration, and the charge type of each surface charge distribution on the ion current rectification performance. The results reveal the ion transport mechanism of ultrashort conical nanopores and provide practical guidance for designing and optimizing nanofluidic devices.

Wood Ion Pumps Enabled by Light-Responsive MoS2-Decorated Nanocellulosic Channels.

Light-driven active ion transport discovered in nanomaterials (e.g., graphene, metal-organic framework, and MXene) implicates crucial applications in membrane-based technology and energy conversion systems. However, it remains a challenge to achieve bulk assembly. Herein, we employ the scalable wood as a framework for in situ growth of MoS2 nanosheets to facilitate light-responsive ion transport. Owing to the aligned and negatively charged wood nanochannels, the MoS2-decorated wood exhibits an excellent nanofluidic conductivity of 8.3 × 10-5 S cm-1 in 1 × 10-6 M KCl. Asymmetric light illumination creates the separation of electrons and holes in MoS2 nanosheets, enabling ions to move uphill against a wide range of concentration gradients. As a result, the MoS2-decorated wood can pump ions uphill against a 20-fold concentration gradient at a light intensity of 300 mW cm-2. When the illumination is applied to the opposite side, the osmotic current along the 20-fold concentration gradient can be enhanced to 75.1 nA, and the corresponding osmotic energy conversion power density increases to more than 12.6 times that of the nonilluminated state. Based on the light-responsive behaviors, we are extending the use of MoS2-decorated wood as the ionic elements for nanofluidic circuits, such as ion switches, ion diodes, and ion transistors. This work provides a facile and scalable strategy for fabricating light-controlled nanofluidic devices from biomass materials.

Toward a multi-layer micro-structured detector for high-energy electron radiotherapy.

The use of electron beams has been rekindled by the advent of ultra-high-dose rate radiotherapy (FLASH) and very high energy electrons (VHEE). The need for development of novel technology for beam monitoring and dosimetry of such beams is of paramount importance prior to their clinical translation. In this work we explore the potential of a multi-layer nanoporous aerogel High-Energy-Current (HEC) detector as a dosimeter for electron beam. The detector does not suffer from radiation damage or signal saturation, making it suitable for very-high-dose-rate applications. Standard dose rates and energies are used to establish reference for FLASH and VHEE. We explore detector response to electron energy and residual range both experimentally and computationally. Multilayer HEC detectors were constructed using 1×-10× basic modules of Aluminum(Al)_aerogel(A)_Tantalum(Ta) with 10-70 µm layer thicknesses. Signals are collected from all electrodes (3-21, depending on module multiplicity) with zero external voltage bias. Measurements are acquired as a function of depth(z) in water equivalent plastic using Varian TrueBeam for energies E=6,9,12,15 MeV (SAD=105cm, 6×6 cone, 1000 MU/min). Computational simulations of identical detector geometries are performed using the 1D deterministic code CEPXS/ONEDANT. Additionally, percent-depth-doses PDD(z), measured with diode in water, are used to explore the response of HEC for various energies and residual ranges. The current measured from Ta electrodes resembles the shape of deposited charges in water and it is proportional to the derivative of the clinical PDD corrected for contribution from photon contamination. The signal is positive on the surface, and it decreases with depth reaching a negative local minimum at z=R50, before increasing again, reaching zero at about the practical range z=Rp. In contrast, the signal from Al electrodes is shaped like the electron PDD(z) shape but with lower signal at the surface and higher bremsstrahlung tail. By subtracting the signal from Ta and Al electrodes we obtained a curve resembling PDD(z,E) after Bremsstrahlung contamination correction. Multi-layer HEC sensors exhibit characteristic responses to electron beams that are unlike responses of ion chambers or diodes. Since the sensor structures are sensitive to electronic disequilibrium, high-Z electrodes give a signal proportional to the charge deposition pattern and can be modeled using the derivative of PDD(z).

Charge-Gradient Sulfonated Poly(ether ether ketone) Membrane with Enhanced Ion Selectivity for Osmotic Energy Conversion.

Engineered asymmetric heterogeneous ion-selective membranes have become a focal point for their improved efficiency in harnessing osmotic energy from ionic solutions with varying salinity. However, achieving both energy conversion efficiency and excellent chemical stability necessitates effectively mitigating the formation of detrimental interface cracks between two different layers. We develop a charge-gradient sulfonated poly(ether ether ketone) (SPEEK) membrane (CG-SPEEK) on a large-scale using a straightforward coating method. As an osmotic energy generator, CG-SPEEK membrane achieves an impressive output power density of 9.2 W m-2 and exhibits ultrahigh cation selectivity (0.99), with an energy conversion efficiency of 48% at a 50-fold NaCl concentration gradient. The results highlight the ion diode effects of CG-SPEEK, driven by a charge density gradient that accelerates cation transport while suppressing ion concentration polarization. Density functional theory simulations provide further insights, revealing that the energy barrier for Na+ ion transport through CG-SPEEK membrane is lower than that through a homogeneous SPEEK membrane. This work not only enhances our understanding of ion transport dynamics but also establishes the CG-SPEEK membrane as a promising candidate for efficient osmotic energy conversion applications.

Ion Transport in Intelligent Nanochannels: A Comparative Analysis of the Role of Electric Field.

This research delves into investigating ion transport behavior within nanochannels, enhanced through modification with a negatively charged polyelectrolyte layer (PEL), aimed at achieving superior control. The study examines two types of electric fields─direct current and alternating current with square, sinusoidal, triangular, and sawtooth waveforms─to understand their impact on ion transport. Furthermore, the study compares symmetric (cylindrical) and asymmetric (conical) nanochannel geometries to assess the influence of overlapping electrical double layers (EDLs) in generating specific electrokinetic behaviors such as ionic current rectification (ICR) and ion selectivity. The research employs the finite element method to solve the coupled Poisson-Nernst-Planck and Navier-Stokes equations under unsteady-state conditions. By considering factors such as electrolyte concentration, soft layer charge density, and electric field type, the study evaluates ion transport performance in charged nanochannels, investigating effects on concentration polarization, electroosmotic flow (EOF), ion current, rectification, and ion selectivity. Notably, the study accounts for ion partitioning between the PEL and electrolyte to simulate real conditions. Findings reveal that conical nanochannels, due to improved EDL overlap, significantly enhance ion transport and related characteristics compared to cylindrical ones. For instance, under ηε = ηD = 0.8, ημ = 2, C0 = 20 mM, and NPEL/NA = 80 mol m-3 conditions, the average EOF for conical and cylindrical geometries is 0.1 and 0.008 m/s, respectively. Additionally, the study explores ion selectivity and rectification based on the electric field type, unveiling the potential of nanochannels as ion gates or diodes. In cylindrical nanochannels, the ICR remains at unity, with lower ion selectivity across waveforms compared to conical channels. Furthermore, rectification and ion selectivity trends are identified as Rf,square > Rf,DC > Rf,triangular > Rf,sinusoidal > Rf,sawtooth and Ssawtooth > Ssinusoidal > Striangular > SDC > Ssquare for conical nanochannels. Our study of ion transport control in nanochannels, guided by tailored electric fields and unique geometries, offers versatile applications in the field of Analytical Chemistry. This includes enhanced sample separation, controlled drug delivery, optimized pharmaceutical analysis, and the development of advanced biosensing technologies for precise chemical analysis and detection. These applications highlight the diverse analytical contributions of our methodology, providing innovative solutions to challenges in chemical analysis and biosensing.

Controllable ion transport in bilayer graphene with charged nanopores

Heterogeneous membrane structures exhibiting ion diode effects have attracted significant interest in energy conversion and storage. Herein, asymmetric double-layer graphene stacks with charged nanopores are constructed and placed in a KCl solution to study the controllable ion transport properties. Ion current rectification (ICR) is observed and the switching ratio is up to 102 by leveraging the asymmetric structure, charge, and interlayer distance. The trapping behavior of cations (K+) and anions (Cl−) in the nanochannels is investigated by applying bias voltages, and peak ion capture occurs at an electric field of E = 0.02 V/Å. The underlying mechanism of ICR is elucidated according to the dependence between the ion current and carrier concentration in the nanopores. The results provide valuable insights into the ICR mechanism and reveal high potential in the energy field.

Investigation of intense pulsed ion beam generation by a magnetically insulated ion diode at a reduced impedance

The intense pulsed ion beam (IPIB) generation was investigated at reduced impedance of a magnetically insulated ion diode. The main goal of our research was to obtain IPIB with adjustable parameters at low current densities. The diode impedance was varied by the external magnetic field current by setting the delay of the accelerator's trigger relative to the launch of the magnetic field generator. The B-applied ion diode adjustably generated IPIB with a current density in the range from 25 to 4 A/cm2. In the matched mode the accelerator generates the ion beam with a current density of about 100 A/cm2. Obtained results of the IPIB current density adjustment allows to irradiate samples in a single vacuum cycle without the change of charging voltage of both magnetic field and accelerating voltage generators. Gold films with a thickness of 10 nm deposited on fluorine-doped tin oxide (FTO)/glass substrates were irradiated to demonstrate the applicability of obtained IPIB for irradiation of thin coatings without their deterioration. Single shot of IPIB with current density of 20 A/cm2 transformed Au film to spherical micro-particles, while after irradiation at the same fluence with 5 pulses of IPIB with current density of 4 A/cm2 Au coating was preserved as a film.

A numerical study on desalination performance enhancement by bipolar ionic diode nanochannels

Bio-inspired ion diodes constructed by asymmetric charged (bipolar) nanochannels have shown outstanding performance in ion transport control which are promising candidates for the development of high-performance water desalination systems. However, understanding of seawater desalination by ionic diode nanochannels is still very limited. This paper uses a numerical model coupling Poisson-Nernest-Planck and Navier-Stokes equations to systematically investigate the desalination behavior of bipolar ion diodes. The effects of nanochannel structure including channel length, diameter, charge polarity, properties of working fluids, and external pressure on the ion rejection efficiency are investigated. The results show that under optimal conditions, the bipolar channel can produce better ion rejection compared to the unipolar channel due to its excellent ion transport control performance, a bipolar ion diode-based desalination system can produce 20 % higher ion rejection rates compared to that of a unipolar channel system. In particular, an external voltage applied to the system is able to further enhance the ion rejection performance of the bipolar channel by more than 27 % compared to that of the case without applied voltage. This work systematically reveals the working mechanism of enhancing water desalination performance by bio-inspired ion diodes and provides a new route for the development of high-efficiency desalination plants.

Modeling of the Dynamics of Plasma Flows and Neutron Generation in a Portable Generator with a Laser-Plasma Ion Diode

Modeling of the Dynamics of Plasma Flows and Neutron Generation in a Portable Generator with a Laser-Plasma Ion Diode

The development of the permanent magnet system for the ion diode isolation

The paper demonstrates the possibility of using the field of permanent magnets for the magnetic isolation of an ion diode and for the ion beam formation. To form a radial magnetic field of a given geometry, ring magnets of complex (special) shape were developed on the base of cylindrical permanent magnets. We also elaborated the design of the anode, magnet frames, and the cathode system of the ion diode. Investigations of the magnetic field parameters were carried out; and experimental data on the accelerating voltage and ion current density were obtained.

A Pseudocapacitor Diode Based on Ion-Selective Surface Redox Effect.

Supercapacitor diode (CAPode) is a novel device that integrates ion diode functionality into a conventional electrical double-layer capacitor and is expected to have great applications in emerging fields such as signal propagation, microcircuit rectification, logic operations, and neuromorphology. Here, a brand new pseudocapacitor diode is reported that has both high charge storage (50.2Cg-1 at 20mVs-1 ) and high rectification (the rectification ratio of 0.79 at 200mVs-1 ) properties, which is realized by the ion-selective surface redox reaction of spinel ZnCo2 O4 in aqueous alkaline electrolyte. Furthermore, an application of the integrated device is demonstrated in the logic gate of circuit system to realize the logic operations of "AND" and "OR". This work not only expands the types of CAPodes, but also provides a train of thought for constructing high-performance capacitive ionic diodes.

Multicharged metal ions generation in a self-magnetically insulated ion diode

A self-magnetically insulated ion diode was used to produce a pulsed beam of metallic ions from explosion emission plasma. The ratio of integral transferred charge for the Al, Ti and Mo ions amounted to at least 63% to the total beam charge. The ion diode had design features, which consisted in a bladed cathode and a removable perforated anode overlay made of VT-8 alloy. Analysis of the charge to mass characteristics of beam ions and the ion current density waveforms by the time of flight methodic with use of a Faraday cup showed the content of aluminum and titanium ions in the third to fourth states of ionization. Keywords: ion diode, metal ions, magnetic spectrometer, track detector CR-39.

A method of real-time monitoring beam output stability of intense pulsed ion beam

Intense pulsed ion beam (IPIB) technology has made remarkable progress in surface modification, mixing, polishing, film deposition, and nano powder synthesis in recent years. However, the surface properties of materials under IPIB irradiation are highly sensitive to beam intensity variations. Deviations from acceptable parameter range can change the surface characteristics and increase prevalence of defects. Consequently, the real-time online monitoring of beam stability during irradiation experiments and promptly identifying of pulses exhibiting significant parameter jitter are of significance in accurately analyzing results and optimizing surface modification. This study presents a fast-response pulse X-ray diagnostic system by employing EJ-200 plastic scintillator, 9266FLB photomultiplier tube, and Tektronic TDS 2024 four-channel oscilloscope. Single particle test demonstrates that the system achieves a time resolution of 6 ns, meeting the requirements for temporal response to detecting pulse X-ray signals with a half-width of ~80 ns. By adjusting the insulation magnetic field strength of the ion diode, the IPIB output level is regulated. The diagnostic system successfully captures X-rays emitted by the external magnetic insulated ion diode operating at different output levels. Simultaneously, the ion beam energy density is measured by using an infrared camera. To mitigate diagnostic errors stemming from target ablation, the maximum energy density is controlled to be below 1.32 J/cm<sup>2</sup>. Analysis results establish a positive correlation between X-ray intensity and ion beam energy density. This relationship arises from the influence of the insulating magnetic field adjustment on the diode's operating voltage, which subsequently affects the bremsstrahlung radiant intensity and ion beam emission intensity. This correlation offers the potential for the real-time monitoring of IPIB beam output stability by utilizing X-ray signals. To further corroborate the synchronized changes in pulse X-ray intensity and ion beam intensity, Faraday cup is employed as an alternative to infrared imaging method for measuring ion current density. Results demonstrate that the amplitude of the X-ray signal changes synchronously with fluctuations of ion current density. It is worth noting that when the output intensity of ion beam deviates significantly (more than 10% of the preset value), the diagnostic system will respond quickly. These findings validate the efficacy of the proposed non-interceptive diagnostic method of real-time monitoring the intense pulsed ion beam output stability.

Control of nanosecond proton bunches in a magnetically insulated ion diode by resonant nuclear reactions of radiative proton capture

To calibrate the detection efficiency of a plastic scintillator that detects prompt gamma quanta from the 19F(p,αγ)16O resonant reaction of radiative proton capture and is used to control the dynamics of the arrival of protons with an energy of about 340 keV accelerated by a magnetically isolated pulsed ion diode, a change the polarity of the diode electrodes to the reverse was used, at which electron bunches were accelerated in the geometry of the Luce diode, forming virtual cathodes. The virtual cathodes in the Luce diode collectively accelerated protons to an energy of about 500 keV, the value of which was determined from the drift velocity of these virtual cathodes, while the number of such protons was determined from the activity of the 13N radionuclide induced by the 457 keV resonance of the 12C(p,γ)13N reaction. Keywords: intense pulsed ion beam, organic scintillator, prompt gamma spectrometry.

Генерация многозарядных ионов металлов в ионном диоде с магнитной самоизоляцией

A self-magnetically insulated ion diode was used to produce a pulsed beam of metallic ions from explosion emission plasma. The ratio of integral transferred charge for the Al, Ti and Mo ions amounted to at least 63% to the total beam charge. The ion diode had design features, which consisted in a bladed cathode and a removable perforated anode overlay made of VT-8 alloy. Analysis of the charge to mass characteristics of beam ions and the ion current density waveforms by the time of flight methodic with use of a Faraday cup showed the content of aluminum and titanium ions in the third to fourth states of ionization.

Контроль наносекундных сгустков протонов в магнитоизолированном ионном диоде по резонансным ядерным реакциям радиационного захвата протонов

To calibrate the detection efficiency of a plastic scintillator that detects prompt gamma quanta from the 19F(p,αγ)16O resonant reaction of radiative proton capture and is used to control the dynamics of the arrival of protons with an energy of about 340 keV accelerated by a magnetically isolated pulsed ion diode, a change the polarity of the diode electrodes to the reverse was used, at which electron bunches were accelerated in the geometry of the Luce diode, forming virtual cathodes. The virtual cathodes in the Luce diode collectively accelerated protons to an energy of about 500 keV, the value of which was determined from the drift velocity of these virtual cathodes, while the number of such protons was determined from the activity of the 13N radionuclide induced by the 457 keV resonance of the 12C(p,γ)13N reaction.