Electron Speed Research Articles

Force free magnetic flux rope with a high current density on the axis

A new model of a force-free magnetic flux rope with a high concentration of electric current on the axis is presented. The general property of axisymmetric force-free magnetic ropes is that with the exit of the top of the magnetic loop-rope into the corona, the external pressure that keeps it from lateral expansion steadily decreases, and with some critical decrease in this pressure, the longitudinal magnetic field of the rope becomes zero on the surface where the electric current changes its sign (it is current inversion surface — CIS). In this case, the force-free parameter α(r) and the azimuthal electric current experience a second-order discontinuity on this surface, so that in the vicinity of CIS their values begin to increase without limit. The current (drift) speed of electrons here will inevitably exceed the speed of ion sound. This serves as a trigger for the heating of non-isothermal plasma (so it turns out Te Ti) and the excitation of plasma ion-acoustic instability of the plasma not only near the CIS, but also in the central region of the rope, on its axis, where the current density is especially high. The appearance of anomalous resistance leads to rapid dissipation of the magnetic field and the generation of a super-Dreicer electric field. The Parker effect, associated with the equalization (with some delay) of the torque along the axis of the rope due to the transfer of the azimuthal field to the region of energy release, leads to quasiperiodic pulsations of hard flare radiation and, ultimately, ensures the flare release of the most part of free magnetic energy accumulated in the rope.

Doped-δ-doped transferred electron device for sustained terahertz signal generation

Abstract The performance of a novel transferred electron device structure aimed at sustaining high-frequency signals in the terahertz (THz) range is investigated. The device uses a highly doped δ-layer to split the n-doped device into two distinct regions, forming a doped-δ-doped configuration. The first region generates high-speed electrons toward the δ-layer, while the second region utilizes negative differential resistance to modulate electron speeds and sustain oscillations. An ensemble self-consistent Monte Carlo model is employed to analyze electron dynamics and THz signal generation in this structure under a constant bias. The design demonstrates superior performance, achieving a fundamental operating frequency of 427 GHz in a 600 nm length InP device, nearly a 50% increase over conventional notch-doped design, while maintaining the current harmonic amplitude. This design achieves higher frequencies without reducing device length and increasing doping density, effectively addressing the trade-off of the Kroemer criterion. The study of the effects of varying doping densities and region lengths on device performance, highlighting the importance of optimizing these parameters to sustain current oscillations and efficiently generate THz signals. This design offers a promising solution for a compact and efficient THz source.

Numerical study of turbulent eddy self-interaction in tokamaks with low magnetic shear. Part II: Nonlinear simulations

Abstract Using local nonlinear gyrokinetic simulations and building up on linear results from a companion paper (Volčokas 2024 Submitted for publication), we demonstrate that turbulent eddies can extend along magnetic field lines for hundreds of poloidal turns in tokamaks with weak or zero magnetic shear s ^ . We observe that this parallel eddy length scales inversely with magnetic shear and at s ^ = 0 is limited by the thermal speed of electrons v th , e . We examine the consequences of these ‘ultra long’ eddies on turbulent transport, in particular, how field line topology mediates strong parallel self-interaction. Our investigation reveals that, through this process, field line topology can strongly affect transport. It can cause transitions between different turbulent instabilities and in some cases triple the logarithmic gradient needed to drive a given amount of heat flux. We also extensively study a novel ‘eddy squeezing’ effect introduced in Volčokas (2023 Nucl. Fusion 63 014003), which reduces the perpendicular size of eddies and their ability to transport energy, thus representing a novel approach to improve confinement. Finally, we investigate the triggering mechanism of Internal Transport Barriers (ITBs) using low magnetic shear simulations, shedding light on why ITBs are often easier to trigger where the safety factor has a low-order rational value.

Optical Properties of Disulfiram and Its Metal Complexes Toward the Photoactive Anticancer Effects

Introduction Disulfiram (DSF) has been used for nearly 70 years as an antidrug and is clinically safe. Recently, it has attracted widespread attention, because it was shown through screening to be effective as an anticancer agent. 1) However, further improvement of the efficacy of DSF is required before it can be used as a therapeutic agent. In this study, we focused on metal diethyldithiocarbamate complexes formed by DSF and metal ion (Cu2+, Fe3+), respectively, to improve the efficacy of the drug by applying it to photodynamic therapy. It aimed to enhance the photoresponses of DSF, with Cu complex (DSF-Cu) and Fe complex (DSF-Fe), and to further improve the anticancer effects with the enhanced photoresponses. Methods Cyclic voltammetry (CV) measurements were performed to determine the electrochemical response of each sample and to investigate their redox properties. In addition, electrochemical impedance spectroscopy (EIS) measurements were conducted under both UV light and dark conditions using a carbon plate coated with the samples as the working electrode to investigate the photo-responsiveness of the samples. Methylene blue (MB) degradation tests were then carried out based on JIS R 1703-2: 2014 to assess whether light irradiation of each sample improves the degradation of organic matter. The HOMO-LUMO levels were estimated by photoelectron yield spectroscopy (PYS) measurements and diffuse reflectance spectroscopy. Results and Discussion From CV results, it could be clearly found the oxidation and reduction peaks for DSF, DSF-Cu, and DSF-Fe, indicating that all samples exhibit an electrochemical response. The EIS results also showed that the radius of the capacitive semicircle was reduced by UV irradiation for all samples, which is considered to be due to the decrease in charge transfer resistance as the charge carriers are transferred more efficiently by UV irradiation. The MB degradation test showed a relatively clear MB degradation rate for DSF-Fe (Figure 1). The reason for the difference in MB degradation rates among the samples can be considered to be the difference in reactive oxygen species (ROS) production ability based on the relationship between the HOMO-LUMO gap position and the oxidation/reduction potentials of water and oxygen in each sample. From the estimated HOMO-LUMO level of each sample, it could find that the reduction potential of oxygen (O2/O2 ―: -0.46 V at pH 7) was below the LUMO level in all samples, but the oxidation potential of water (O2/H2O: 0.81 V at pH 7) and the oxidation potential of MB potential (>1.2 V) did not exceed the HOMO level (Figure 2). Therefore, it is possible that MB was oxidatively decomposed by O2 ― produced by the sample's own oxidation and reduction of dissolved oxygen. The difference in the decomposition rate may be due to the difference in the recombination speed of excited electrons. The respective gap energies suggest that DSF-Cu and DSF-Fe can also respond to visible light.[References](1) Yuya Terashima, et al., Nature Communications 11 (609), 2020.(2) S. Trasatti, Pure & Appl Chem. 58 (7), 955-966, 1986. Figure 1

CHANG-ES

Context. Cosmic rays may be dynamically very important in driving large-scale galactic winds. Edge-on galaxies give us an outsider’s view of radio haloes, and of their extra-planar cosmic-ray electrons and magnetic fields. Aims. We present a new radio continuum imaging study of the nearby edge-on galaxy NGC 4217. We examine the distribution of extra-planar cosmic rays and magnetic fields. We observed it with both the Jansky Very Large Array (JVLA) in the S band (2–4 GHz) and the LOw Frequency ARray (LOFAR) at 144 MHz. Methods. We measured vertical intensity profiles and exponential scale heights. We re-imaged both the JVLA and LOFAR data at matched angular resolution in order to measure radio spectral indices between 144 MHz and 3 GHz. Confusing point-like sources were subtracted prior to imaging. We then fitted intensity profiles with cosmic-ray electron advection models, using an isothermal wind model that is driven by a combination of pressure from the hot gas and cosmic rays. Results. We discover a large-scale radio halo on the north-western side of the galactic disc. The morphology is reminiscent of a bubble extending up to 20 kpc from the disc. We find spectral ageing in the bubble, which allowed us to measure the advection speeds of the cosmic-ray electrons, which accelerate from 300 to 600 km s−1. Assuming energy equipartition between the cosmic rays and the magnetic field, we estimate the bubble may have been inflated by a modest 10% of the kinetic energy injected by supernovae over its dynamical timescale of 35 Myr. While no active galactic nucleus (AGN) has been detected, such activity in the recent past cannot be ruled out. Conclusions. Non-thermal bubbles with sizes of tens of kiloparsecs may be a ubiquitous feature of star-forming galaxies, and if so this would demonstrate the influence of feedback. Determining possible contributions by AGN feedback will require deeper observations.

Toroidal Alfvén mode instability driven by plasma current in low-density Ohmic plasmas of the spherical tori

Due to intrinsically low magnetic fields, at low density the drift speed of the current-carrying electrons in spherical tokamaks can exceed fraction of the Alfvén speed sufficient for the excitation of the Alfvén gap modes. A particular case of the toroidal mode, observed during minor disruptions in Ohmic shots on SUNIST [Liu et al., Phys. Plasmas 23, 120706 (2016)], is considered in the present communication. Due to the negligible effect of the electron pressure gradient, the growth rate scales linearly with the drift speed, with slope inversely proportional to electron thermal velocity. In the absence of continuum damping, the threshold value of the drift speed for TAE excitation is independent of electron temperature.

Bright and durable scintillation from colloidal quantum shells

Efficient, fast, and robust scintillators for ionizing radiation detection are crucial in various fields, including medical diagnostics, defense, and particle physics. However, traditional scintillator technologies face challenges in simultaneously achieving optimal performance and high-speed operation. Herein we introduce colloidal quantum shell heterostructures as X-ray and electron scintillators, combining efficiency, speed, and durability. Quantum shells exhibit light yields up to 70,000 photons MeV−1 at room temperature, enabled by their high multiexciton radiative efficiency thanks to long Auger-Meitner lifetimes (>10 ns). Radioluminescence is fast, with lifetimes of 2.5 ns and sub-100 ps rise times. Additionally, quantum shells do not exhibit afterglow and maintain stable scintillation even under high X-ray doses (>109 Gy). Furthermore, we showcase quantum shells for X-ray imaging achieving a spatial resolution as high as 28 line pairs per millimeter. Overall, efficient, fast, and durable scintillation make quantum shells appealing in applications ranging from ultrafast radiation detection to high-resolution imaging.

Free Electron-Plasmon Coupling Strength and Near-Field Retrieval through Electron Energy-Dependent Cathodoluminescence Spectroscopy.

Tightly confined optical near fields in plasmonic nanostructures play a pivotal role in important applications ranging from optical sensing to light harvesting. Energetic electrons are ideally suited to probing optical near fields by collecting the resulting cathodoluminescence (CL) light emission. Intriguingly, the CL intensity is determined by the near-field profile along the electron propagation direction, but the retrieval of such field from measurements has remained elusive. Furthermore, the conditions for optimum electron near-field coupling in plasmonic systems are critically dependent on such field and remain experimentally unexplored. In this work, we use electron energy-dependent CL spectroscopy to study the tightly confined dipolar mode in plasmonic gold nanoparticles. By systematically studying gold nanoparticles with diameters in the range of 20-100 nm and electron energies from 4 to 30 keV, we determine how the coupling between swift electrons and the optical near fields depends on the energy of the incoming electron. The strongest coupling is achieved when the electron speed equals the mode phase velocity, meeting the so-called phase-matching condition. In aloof experiments, the measured data are well reproduced by electromagnetic simulations, which explain that larger particles and faster electrons favor a stronger electron near-field coupling. For penetrating electron trajectories, scattering at the particle produces severe corrections of the trajectory that defy existing theories based on the assumption of nonrecoil condition. Therefore, we develop a first-order recoil correction model that allows us to account for inelastic electron scattering, rendering better agreement with measured data. Finally, we consider the albedo of the particles and find that, to approach unity coupling, a highly confined electric field and very slow electrons are needed, both representing experimental challenges. Our findings explain how to reach unity-order coupling between free electrons and confined excitations, helping us understand fundamental aspects of light-matter interaction at the nanoscale.

Fabrication of TiO2 photoelectrodes doped with copper and zirconium to improve electron generation and flow in dye-sensitized solar cell

Dye-sensitized solar cell (DSSC) are devices that convert solar light into electricity using a semiconductor substance, e.g. TiO2. Although DSSC are environmentally friendly and economical, they exhibit a low energy conversion efficiency. In this study, to improve its energy conversion efficiency, a DSSC in which TiO2 was doped with transition metals (TMs) such as Cu and Zr was fabricated by a sol–gel method. Doping with TMs extended the light-absorption range of TiO2 to the visible-light region, generating more electrons and improving electrical conductivity. The successful doping of Cu, Zr in the fabricated photoelectrode was confirmed by X-ray diffraction (XRD) and FESEM–energy dispersive X-ray spectroscopy (EDS) analyses, and doping with Cu, Zr increased the dye adsorption amount and current density of DSSC. In addition, the electron-transfer resistance was confirmed to be reduced by electrochemical impedance spectroscopy (EIS) analysis, and the electron movement, speed, and lifetime were improved by Intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) analyses. The electrical properties of the Cu, Zr-doped TiO2 photoelectrodes were determined from the chemical capacitance and recombination resistance calculations, and the results revealed that the efficiency was improved by Cu, Zr doping. In conclusion, the Cu, Zr doping of the photoelectrode improved the electron generation and flow of TiO2, thereby increasing the energy conversion efficiency of the DSSC by up to 3.28%

Temperature-induced disruptive growth rate behavior due to streaming instability in semiconductor quantum plasma with nanoparticles

The nature of the growth rate due to streaming instability in a semiconductor quantum plasma implanted with nanoparticles has been analyzed using the quantum hydrodynamic model. In this study, the intriguing effect of temperature, beam electron speed, and electron-hole density on growth rate and frequency is investigated. The results show that the growth rate demonstrates a nonlinear behavior, strongly linked to the boron implantation, beam electron streaming speed and quantum correction factor. A noteworthy finding in this work is the discontinuous nature of the growth rate of streaming instability in boron implanted semiconducting plasma system. The implantation leads to a gap in the growth rate which further gets enhanced upon increase in concentration of implantation. This behavior is apparent only for a specific range of the ratio of thermal speed of the electrons to that of the holes.

Review of: "as well as mobility, which is a measure of the ability and speed of free electrons to move, attributed"

Review of: "as well as mobility, which is a measure of the ability and speed of free electrons to move, attributed"

On the Properties of Inverse Compton Spectra Generated by Upscattering a Power-law Distribution of Target Photons

Relativistic electrons are an essential component in many astrophysical sources, and their radiation may dominate the high-energy bands. Inverse Compton (IC) emission is the radiation mechanism that plays the most important role in these bands. The basic properties of IC, such as the total and differential cross sections, have long been studied; the properties of the IC emission depend strongly not only on the emitting electron distribution but also on the properties of the target photons. This complicates the phenomenological studies of sources, where target photons are supplied from a broad radiation component. We study the spectral properties of IC emission generated by a power-law distribution of electrons on a power-law distribution of target photons. We approximate the resulting spectrum by a broken-power-law distribution and show that there can be up to three physically motivated spectral breaks. If the target photon spectrum extends to sufficiently low energies, (m e and c are electron mass and speed of light, respectively; and are the minimum/maximum energies of target photons and electrons, respectively), then the high-energy part of the IC component has a spectral slope typical for the Thomson regime with an abrupt cutoff close to . The spectra typical for the Klein–Nishina regime are formed above . If the spectrum of target photons features a cooling break, i.e., a change of the photon index by 0.5 at ε br, then the transition to the Klein–Nishina regime proceeds through an intermediate change of the photon index by 0.5 at .

Influence of Vacancy Defects on the Interfacial Structural and Optoelectronic Properties of ZnO/ZnS Heterostructures for Photocatalysis

Hybrid density functional theory has been employed to study the influence of interfacial oxygen (O), sulfur (S) and zinc (Zn) vacancies on the optoelectronic properties of ZnO/ZnS heterostructure. The results show that the O, S, and Zn vacancies can decrease cell volume of the ZnO/ZnS heterostructure, leading to slight deformation from the perfect heterostructure. The quasi-band gap of ZnO/ZnS heterostructure is remarkably reduced compared to the ZnO surface. Hence, the visible light response is enhanced in ZnO/ZnS heterostructure, which can be further improved by creating an interfacial S or O vacancy. Moreover, the removal of S or O atoms can generate lone electrons in the system, which can enhance n-type conductivity of the heterostructure. The O and S vacancies improve the contribution of the atomic orbitals of ZnZnO (Zn atom in ZnO), ZnZnS (Zn atom in ZnS), S and O to the valence band maximum (VB) of the heterostructure; while the Zn-vacancy remarkably improves the contribution of S states to the conduction band minimum (CB). The resultant type-II band alignment and large difference between the migration speed of electrons and holes can efficiently separate the photogenerated electron-hole pairs. The CB edge positions are more negative than the redox potentials of CO2/CO and H2O/H2, and the VB edge positions are more positive than the redox potential of O2/H2O. Hence, all the systems under investigation can be potentially used as efficient photocatalysts for various applications like CO2 reduction and water splitting.

Development of gold nanoparticles composite functionalized bimetallic metal-organic framework nanozymes and integrated smartphone to detection isoniazid

It is still an issue of continuous exploration to construct nanozymes with improved activity and to investigate catalytic mechanism. This study develops an open metal nodes integration strategy to prepare functionalized bimetallic metal-organic frameworks nanozymes (NMOF-CoFe1.8). Then Au nanoparticles are grown in-situ utilizing electrostatic effects to acquire composite nanozymes (Au@NMOF). Functionalization leads to deficiency of ligand in MOF and Au nanoparticles alter the surface charge to attract the chromogenic substrate with opposite charge. One-dimensional mixed-valence metal-oxygen chains with open sites inside Au@NMOF constitute sub-nanochannels with the functions of isolating external environment and transporting substances. Cobalt adsorption centers, iron and gold catalytic centers realizes the catalytic microenvironment, enhances the mass and electron transfer rate and speeds up the generation of hydroxyl radicals. The Michaelis constant of H2O2 is 0.0664 mM and of 3,3′,5,5′-tetramethylbenzidine is 0.0879 mM, which all proves its excellent activity. As non-competitive enzyme inhibitor, isoniazid forms irreversible ternary complex with the chromogenic substrate and Au@NMOF, whose inhibition constant is 0.0229 mmol. A colorimetric sensing platform with integrated smartphone based on hydrogel is constructed to detect isoniazid. The linear of isoniazid colorimetric sensing is 0.25–120 μM with the low detection limits of 0.2 μM. The assay platform is successfully applied to the human urine and serum samples assay with the recoveries of 97.0–103.72% and relative standard deviations less than 3%. It is expected to be practically applied due to its good reproducibility, feasibility and portability.

Diagnosis of fast electron transport by coherent transition radiation

Transport of fast electrons in overdense plasmas is of key importance in high energy density physics. However, it is challenging to diagnose the fast electron transport in experiments. In this article, we study coherent transition radiation (CTR) generated by fast electrons on the back surface of the target by using 2D and 3D first-principle particle-in-cell (PIC) simulations. In our simulations, aluminum targets of 2.7 g cc−1 are simulated in two different situations by using a newly developed high order implicit PIC code. Comparing realistic simulations containing collision and ionization effects, artificial simulations without taking collision and ionization effects into account significantly underestimate the energy loss of electron beams when transporting in the target, which fail to describe the complete characteristics of CTR produced by electron beams on the back surface of the target. Realistic simulations indicate the diameter of CTR increases when the thickness of the target is increased. This is attributed to synergetic energy losses of high flux fast electrons due to Ohm heating and colliding drags, which appear quite significant even when the thickness of the solid target only differs by micrometers. Especially, when the diagnosing position is fixed, we find that the intensity distribution of the CTR is also a function of time, with the diameter increased with time. As the diameter of CTR is related to the speed of electrons passing through the back surface of the target, our finding may be used as a new tool to diagnose the electron energy spectra near the surface of solid density plasmas.

Implanting CuS Quantum Dots into Carbon Nanorods for Efficient Magnesium-Ion Batteries.

Magnesium-ion batteries (MIBs) are emerging as potential next-generation energy storage systems due to high security and high theoretical energy density. Nevertheless, the development of MIBs is limited by the lack of cathode materials with high specific capacity and cyclic stability. Currently, transition metal sulfides are considered as a promising class of cathode materials for advanced MIBs. Herein, a template-based strategy is proposed to successfully fabricate metal-organic framework-derived in-situ porous carbon nanorod-encapsulated CuS quantum dots (CuS-QD@C nanorods) via a two-step method of sulfurization and cation exchange. CuS quantum dots have abundant electrochemically active sites, which facilitate the contact between the electrode and the electrolyte. In addition, the tight combination of CuS quantum dots and porous carbon nanorods increases the electronic conductivity while accelerating the transport speed of ions and electrons. With these architectural and compositional advantages, when used as a cathode material for MIBs, the CuS-QD@C nanorods exhibit remarkable performance in magnesium storage, including a high reversible capacity of 323.7 mAh g-1 at 100mA g-1 after 100 cycles, excellent long-term cycling stability (98.5 mAh g-1 after 1000 cycles at 1.0 A g-1 ), and satisfying rate performance (111.8mA g-1 at 1.0 A g-1 ).

Electron-induced nonlinear dynamics in atomic chains

Low-energy free electrons can induce a nonlinear optical response in the collective oscillations of conduction electrons in nanostructured materials, but the dependence of this free-electron-induced nonlinearity on the electronic structure of matter is not fully understood. A study of time-domain simulations of electron-induced nonlinear dynamics in linear atomic chains with metallic, semiconducting, and topologically insulating character reveals that the Fermi velocity sets the threshold speed of an external free electron to trigger a nonlinear response.

Cyclic voltammetry electrodeposition of self-standing Ni–Fe–Sn ternary alloys for accelerating alkaline hydrogen evolution

Designing cost-effective and high-efficiency non-noble electrocatalysts for the hydrogen evolution reaction (HER) remains a significant challenge for electrochemical water splitting to store clean and renewable energy. Herein, we have developed Ni–Fe–Sn electrocatalysts grown on Ni foam (Ni–Fe–Sn@NF) for the HER through a simple and facile synthetic route of cyclic voltammetry electrodeposition. The optimized Ni–Fe–Sn electrocatalysts possess excellent electrocatalysis toward hydrogen evolution with a low overpotential of 103 mV at a current density of 10 mA cm−2, together with a small Tafel slope value of 97.4 mV·dec−1 in 1 M KOH. The electrocatalyst also features excellent stability even after 2000 cycles and strong durability after 50 h under alkaline condition. The high HER performance can be attributed to the moderately optimized electronic structure of the Ni, Fe, and Sn center and bind-free nature of the electrode, which facilitates electron transfer and speeds up reaction kinetics. Moreover, the improved electrochemical surface area also enhances the performance on hydrogen production. This strategy presents a facile and simple tactic for the synthesis of noble-metal-free electrocatalysts with excellent HER performance.

Energy Coupling Mechanism of Electrodeless Plasma Thruster with Rotating Electric Field

The energy coupling process indicated by particle density, speed, current density, and power absorption in a thruster using a rotating electric field was simulated using a one dimension, three velocities electrostatic particle-in-cell (PIC) code under different external magnetic field strengths varying from 0 to 80 G. The longer interaction between electrons and the sheath layer due to the increased magnetic field results in a significant decrease in electron speed from at 0 G to at 80 G; a reduction in electron power absorption from at 0 G to at 80 G; and an increase in electron density, current density, and total current density about 69.48, 21.11, and 5.4%, respectively. While ions cannot respond to the changes in time because of their large mass. Three types of currents, namely, electron, ion, and displacement, are primarily present throughout the discharge process. Ion current is significantly less than the other two. The characteristics of plasma described exhibit a nonlinear change, dropping at first and then rising when the magnetic field is strengthened. The results have implications for both choosing the magnetic field for the thruster and thoroughly investigating the energy coupling inside the plasma.

Controlled synthesis of 3D urchinlike niobium tungsten oxide nanostructure for fast hydrogen ion storage

The shear crystal structure through metal doping can effectively promote the transport speed of ions and electrons in metal oxides, which has important dynamic significance for the design of high-performance energy storage materials. Herein, a 3D urchinlike niobium tungsten oxide (NWO) nanostructure as an efficient hydrogen ion storage material is reported for the first time, which exhibits a capacity of 88mAh g−1 at 20 °C (1 °C = 100 mA g−1). The large specific capacity of the 3D urchinlike NWO nanostructure is ascribed to the reversible reaction of a great quantity of W6+, W5+ and W4+ in the process of protonation and deprotonation processes. In addition, hydrogen ions can still be stored in large and stable quantities, even at rates as high as 100 °C (75 mAh g−1 at 100 °C). The improvement of hydrogen ion storage properties is arising from an optimized morphology of niobium tungsten oxide via tuning of the crystal structure. The high specific superficial area 3D urchinlike shape with rich one-dimensional nanostructures significantly shortens charge-carrier transport distances, ensuring rapid interfacial electronics movement to polish up ion storage kinetics. Consequently, this crystallographic shear structure strategy to boost hydrogen ion storage capacity may be universal and is likely to pave the way toward highly capacity hydrogen ion energy storage systems.