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Metals exhibit nonequilibrium electron and lattice subsystems at transient times following femtosecond laser excitation. In the past four decades, various optical spectroscopy and time-resolved diffraction methods have been used to study electron–phonon coupling and the effects of underlying dynamical processes. Here, we take advantage of the surface specificity of reflection ultrafast electron diffraction (UED) to examine the structural dynamics of photoexcited metal surfaces, which are apparently slower in recovery than predicted by thermal diffusion from the profile of absorbed energy. Fast diffusion of hot electrons is found to critically reduce surface excitation and affect the temporal dependence of the increased atomic motions on not only the ultrashort but also sub-nanosecond times. Whereas the two-temperature model with the accepted physical constants of platinum can reproduce the observed surface lattice dynamics, gold is found to exhibit appreciably larger-than-expected dynamic vibrational amplitudes of surface atoms while keeping the commonly used electron–phonon coupling constant. Such surface behavioral difference at transient times can be understood in the context of the different strengths of binding to surface atoms for the two metals. In addition, with the quantitative agreements between diffraction and theoretical results, we provide convincing evidence that surface structural dynamics can be reliably obtained by reflection UED even in the presence of laser-induced transient electric fields. [ABSTRACT FROM AUTHOR]

A dynamic Monte Carlo (MC) method recently proposed by us [Nagai et al., J. Chem. Phys. 156, 154506 (2022)] to describe single-particle diffusion of a molecule in a heterogeneous space with position-dependent diffusion coefficient and free energy is generalized here to n-particle dynamics, where n molecules diffuse in heterogeneous media interacting via their intermolecular potential. Starting from the master equation, we give an algebraic proof that the dynamic MC transition probabilities proposed here produce particle trajectories that satisfy the n-particle diffusion equation with position-dependent diffusion coefficient D 0 i ( r i ) , free energy F 1 i ( r i ) , and intermolecular interactions Vij(ri, rj). The MC calculations based on this method are compared to molecular dynamics (MD) calculations for two-dimensional heterogeneous Lennard-Jones test systems, showing excellent agreement of the long-distance global diffusion coefficient between the two cases. Thus, the particle trajectories produced by the present MC transition probabilities satisfy the n-particle diffusion equation, and the diffusion equation well describes the long-distance trajectories produced by the MD calculations. The method is also an extension of the conventional equilibrium Metropolis MC calculation for homogeneous systems with a constant diffusion coefficient to the dynamics in heterogeneous systems with a position-dependent diffusion coefficient and potential. In the present method, interactions and dynamics of the real systems are coarse-grained such that the calculation cost is drastically reduced. This provides an approach for the investigation of particle dynamics in very complex and large systems, where the diffusing length is of sub-micrometer order and the diffusion time is of the order of milliseconds or more. [ABSTRACT FROM AUTHOR]

A large open-circuit voltage (VOC) deficit is the major challenge hindering the efficiency improvement of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells. Cation substitution, or doping, is usually an effective strategy to achieve carrier regulation and improve efficiency. In this work, we developed a rare-earth element lanthanum (La) doped CZTSSe thin-film solar cell by directly introducing La3+ ions into the CZTS precursor solution. Such a proposed La doping approach could effectively enhance light harvesting, adjust the bandgap, and increase the electron diffusion length. Furthermore, appropriate concentrations of La doping can reduce harmful defect cluster. Benefiting from the La doping, the VOC significantly increases from 431 to 497 mV. Consequently, the power conversion efficiency is enhanced significantly from 6.54% (VOC = 431 mV, JSC = 25.50 mA/cm2, FF = 58.28%) for the reference cell to 10.21% (VOC = 497 mV, JSC = 35.20 mA/cm2, FF = 58.41%) for the optimized La-doped cell. This research provides a new direction for enhancing the performance of CZTSSe cells, offering promising prospects for the future of CZTSSe thin-film solar cells. [ABSTRACT FROM AUTHOR]

Diffusion of electrons over distances on the order of 100 μm has been observed in crystals of a small tetraheme cytochrome (STC) from Shewanella oneidensis [J. Huang et al. J. Am. Chem. Soc. 142, 10459–10467 (2020)]. Electron transfer between hemes in adjacent subunits of the crystal is slower and more strongly dependent on temperature than had been expected based on semiclassical electron-transfer theory. We here explore explanations for these findings by molecular-dynamics simulations of crystalline and monomeric STC. New procedures are developed for including time-dependent quantum mechanical energy differences in the gap between the energies of the reactant and product states and for evaluating fluctuations of the electronic-interaction matrix element that couples the two hemes. Rate constants for electron transfer are calculated from the time- and temperature-dependent energy gaps, coupling factors, and Franck–Condon-weighted densities of states using an expression with no freely adjustable parameters. Back reactions are considered, as are the effects of various protonation states of the carboxyl groups on the heme side chains. Interactions with water are found to dominate the fluctuations of the energy gap between the reactant and product states. The calculated rate constant for electron transfer from heme IV to heme Ib in a neighboring subunit at 300 K agrees well with the measured value. However, the calculated activation energy of the reaction in the crystal is considerably smaller than observed. We suggest two possible explanations for this discrepancy. The calculated rate constant for transfer from heme I to II within the same subunit of the crystal is about one-third that for monomeric STC in solution. [ABSTRACT FROM AUTHOR]

Spin–orbit torque provides an efficient strategy for electric manipulation of magnetization. However, Joule heat accompanying with electron motion in the electron-mediated spin current result in unavoidable power dissipation. Moreover, the spin diffusion length in electron-mediated spin current is relatively short, preventing the transmission of spin information over long distances. Magnon-mediated spin current, without moving electrons, can be an excellent alternative to the conventional spin current. Magnon-mediated transfer torque effect has been reported in several previous works. Here, we report the magnon-mediated spin Hall magnetoresistance (SMR) and unidirectional magnetoresistance (UMR) in Pt/NiO/NiFe structures. The significant SMR and UMR were observed in the samples with the NiO thickness up to 60 nm, demonstrating the efficient transmission of magnon-mediated spin current over long distances in the NiO layer. In addition, we observed current-induced in-plane magnetization switching in the NiFe layer via the UMR measurement. These results demonstrated the possibility for developing the efficient spintronic devices operated by magnons. [ABSTRACT FROM AUTHOR]

The intrinsic carrier density of 4H-SiC at temperatures ranging from 294 to 595 K was derived by analyzing a collector current in an npn-type SiC bipolar junction transistor, the structure of which was designed based on a device simulation. The obtained intrinsic carrier density was in good agreement with the value calculated from the bandgap and effective densities of states taking multiple and non-parabolic SiC bands into account. The coincidence of the intrinsic carrier density obtained by these two different approaches indicates the usefulness of the proposed method and the validity of the evaluated value of intrinsic carrier density. The temperature dependence of the bandgap was also estimated from the deduced intrinsic carrier density and compared with an empirical formula. The derived bandgap agreed well with the empirical formula showing bandgap shrinkage at high temperatures. The errors in evaluating the intrinsic carrier density and the bandgap caused by the estimation of the hole density and electron mobility in the base layer are also discussed for the proposed method. [ABSTRACT FROM AUTHOR]

Intermolecular hyperfine relaxation-induced dipolar modulation enhancement experiment (ih-RIDME) is a pulse EPR experiment that can be used to probe the properties of a nuclear spin bath in the vicinity of an unpaired electron. The underlying mechanism is the hyperfine spectral diffusion of the electron spin during the mixing block. A quantitative description of the diffusion kinetics being applied to establish the ih-RIDME data model allows to extend this method for systems with heterogeneous nuclear arrangements assuming a distribution of the local nuclear densities. The heterogeneity can stem from the solvent or the intrinsic nuclei of structurally flexible (macro)molecule. Therefore, the fitted distribution function can further serve for heterogeneity characterization, quantification and structure-based analysis. Here, we present a detailed introduction to the principles of the ih-RIDME application to heterogeneous systems. We discuss the spectral resolution, determination of the spectral diffusion parameters and influence of noise in the experimental data. We further demonstrate the application of the ih-RIDME method to a model spin-labeled macromolecule with unstructured domains. The fitted distribution of local proton densities was reproduced with the help of the Monte-Carlo-generated conformational ensemble. Finally, we discuss several pulse sequences exploiting the HYperfine Spectral Diffusion Echo MOdulatioN (HYSDEMON) effect with an improved signal-to-noise ratio. [ABSTRACT FROM AUTHOR]

The regular octahedral CdS/K 2 Nb 2 O 6 core-shell Z-Scheme heterojunction is synthesized via an approach of hydrothermal-chemical method. The CdS/K 2 Nb 2 O 6 nano-heterojunction (CdS/KNO-3) exhibits arresting enhanced photocatalytic HER (∼634.39 μmol g−1 h−1)/degradation (∼0.05428 min−1) than the monomer K 2 Nb 2 O 6 (∼27.8/14.4 folds) and CdS (∼20.3/10.0 folds), including a decent stability (average HER of ∼621.39 μmol∙g−1 h−1). It can be mainly attributed to the CdS/K 2 Nb 2 O 6 Z-Scheme heterojunction with appropriate potential gradient can promote the interface carrier driving to optimize carrier efficiency, including increasing carrier transport, extending carrier lifetime and reducing recombination. Additionally, the octahedral core-shell nanostructure can provide numerous active sites for decreasing overpotential and promoting electron diffusion, while improving the solar efficiency (high solar response of CdS), including shorting carrier pathway for photocorrosion optimization and increasing structural stability. [Display omitted] • Z-scheme heterojunction optimize carrier efficiency by greater Fermi levels gradient. • Core-shell structure can increase active sites to promote electron diffusion. • CdS nano-shell can enhance visible light response and shorten carrier pathway. • Regular octahedral nano-structure can increase structural stability. [ABSTRACT FROM AUTHOR]

One‐dimensional scanning optical beam‐induced current (OBIC) measurements have been carried out on polymer bulk heterojunction (BHJ) photovoltaic cells with a planar, or lateral configuration. The planar P3HT:PCBM cells have parallel aluminum or gold electrodes that are 390 to 560 micrometers apart. When a focused laser beam is scanned across the electrode gap, photocurrent or photovoltage is recorded as a function of beam position along with the transmission of the excitation beam. Despite the large electrode gap size, cells with symmetric Al/Al electrodes exhibit significant photocurrent and photovoltage which are the highest at the electrode interfaces and null at the cell center. The OBIC in these large planar polymer BHJ cells is attributed to the metal/BHJ blend Schottky junction. The larger Schottky barrier of the Al/BHJ junction gives rise to a stronger OBIC response than the Au/BHJ junction. The photocurrent and photovoltage always have opposite signs and are antisymmetric about the cell center. In asymmetric Al/Au cells, the electrode work function difference contributes an additional built‐in field/potential drop and significantly modifies the photocurrent and photovoltage profiles. The depletion width of the Al/BHJ Schottky junction is 110–120 μm, while the minority electron diffusion length is determined to be 43.8 μm. [ABSTRACT FROM AUTHOR]

As a kind of anode material with high theoretical sodium storage capacity for sodium-ion batteries (SIBs), MoS2 has been widely studied. However, its low conductivity and large volume change hamper its application in SIBs. Herein, MoS2 microspheres were first synthesized through the sulfidation of molybdenyl acetylacetonate via a solvothermal method and then successfully covered with a few layers of MXene nanosheets using the electrostatic assembly method. The ratio of MoS2 to MXene was also investigated. The obtained MXene@MoS2 composite has a large specific surface area due to its porous and non-stacked structure, which benefits the enhancement of ion and electron diffusion kinetics in SIBs. Therefore, the MXene@MoS2 composite has a specific capacity of 257.8 mA h g−1 after 1000 cycles at a current density of 1 A g−1 with a capacity retention of 95.7% and excellent rate performance (220.8 mA h g−1 at 5 A g−1). [ABSTRACT FROM AUTHOR]

Relativistic charged particle beam can be used as a destructive beam weapon in space for debris removal tasks. The trajectories of charged particles are affected by both electric and magnetic forces in the Earth's magnetic field. In this paper, we firstly analyzed the correlation parameters of the charged particle beam as a weapon when it is propagated in the geomagnetic field. Then, the models were constructed based on COMSOL Multiphysics, and the IGRF model was adopted in the simulation. The gyroradius and the related uncertainty were analyzed by simulation of the charged particle transport in the geomagnetic field at different altitudes. The charged beam spot radius divergency was also simulated. The geomagnetic field can inhibite the diffusion of the electron beam. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) nonlayered metal compounds with porous structure show broad application prospects in electrochemistry‐related fields due to their abundant active sites, open ions/electrons diffusion channels, and faradaic reactions. However, scalable and universal synthesis of 2D porous compounds still remains challenging. Here, inspired by blowing gum, a metal‐organic gel (MOG) rapid redox transformation (MRRT) strategy is proposed for the mass production of a wide variety of 2D porous metal oxides. Adequate crosslinking degree of MOG precursor and its rapid redox with NO3− are critical for generating gas pressure from interior to exterior, thus blowing the MOG into 2D carbon nanosheets, which further act as self‐sacrifice template for formation of oxides with porous and ultrathin structure. The versatility of this strategy is demonstrated by the fabrication of 39 metal oxides, including 10 transition metal oxides, one II‐main group oxide, two III‐main group oxides, 22 perovskite oxides, four high‐entropy oxides. As an illustrative verification, the 2D transition metal oxides exhibit excellent capacitive deionization (CDI) performance. Moreover, the assembled CDI cell could act as desalting battery to supply electrical energy during electrode regeneration. This MRRT strategy offers opportunities for achieving universal synthesis of 2D porous oxides with nonlayered structures and studying their electrochemistry‐related applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbon-encapsulated MnSe-FeSe nanowires have been fabricated. • Heterostructure accelerates the electron transfer and ion diffusion. • MnSe-FeSe@C exhibits excellent rate capability and prolonged cycling durability. The natural abundance of sodium has fostered the development of sodium-ion batteries for large-scale energy storage. However, the low capacity of the anodes hinders their future application. Herein, carbon-encapsulated MnSe-FeSe nanorods (MnSe-FeSe@C) have been fabricated by the in-situ transformation from polydopamine-coated MnO(OH)-Fe 2 O 3. The heterostructure constructed by MnSe and FeSe nanocrystals induces the formation of built-in electric fields, accelerating electron transfer and ion diffusion, thereby improving reaction kinetics. In addition, carbon enclosure can buffer the volumetric stress and enhance the electrical conductivity. These aspects cooperatively endow the anode with superior cycling stability and distinguished rate performance. Specifically, the discharge capacity of MnSe-FeSe@C reaches 414.3 mA h g−1 at 0.1 A g−1 and 388.8 mA h g−1 even at a high current density of 5.0 A g−1. In addition, it still retains a high reversible capacity of 449.2 mA h g−1 after 700 long cycles at 1.0 A g−1. Further, the ab initio calculation has been employed to authenticate the existence of the built-in electric field by Bader charge, indicating that 0.24 electrons in MnSe were transferred to FeSe. The in-situ XRD has been used to evaluate the phase transition during the charging/discharging process, revealing the sodium ion storage mechanism. The construction of heterostructure material paves a new way to design performance-enhanced anode materials for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

ZnWO4@NiCo2O4 core–shell nanosheet array composites are synthesized on nickel foam via a two-step hydrothermal method. The optimal conditions, including a Ni(NO3)2·6H2O to Co(NO3)2·6H2O molar ratio of 2 : 1, 12 hours reaction time, and 120 °C temperature, yield a specific capacitance of 875 C g−1 at 1 A g−1. The electrode also maintains 81.1% capacitance after 10 000 cycles. The material's performance is attributed to its core–shell structure, which enhances ion diffusion and electron transport. This study presents a viable approach for high-performance supercapacitor electrodes. [ABSTRACT FROM AUTHOR]

Urea oxidation reaction (UOR) can be used as an alternative to oxygen evolution reaction (OER) for hydrogen production by electrolysis of water, and as an anode reaction for direct urea fuel cells (DUFC). However, the slow kinetics of UOR restricts its wide application. Therefore, it is of great significance to design and prepare cheap and high-performance non-noble metal based UOR catalysts. In this work, Ni/NiO–NiWO 4 -2 sample prepared by solvent evaporation method has a mesoporous feature verified by the structural characterization, which is conducive to electrolyte diffusion and electron transport. Electrochemical tests show that the Ni/NiO–NiWO 4 -2 sample has good UOR catalytic activity, namely, the potential required by UOR is 1.669 V (vs RHE) at the current density of 270.44 mA cm−2. The excellent performance of Ni/NiO–NiWO 4 -2 is ascribed to that its mesoporous structure facilitates the diffusion of the electrolyte and exposes more active areas, the existence of metal W weakens the poisoning of Ni3+ active components and reduces the energy barrier of UOR confirmed by density functional theory, thus enhancing the performance of UOR. Ni and W oxides were constructed by solvent evaporation method. In alkaline medium, the current density reached 270.44 mA cm−2@ 1.669V, which is due to W doping regulates electron distribution and reduces energy barrier of UOR confirmed by DFT. [Display omitted] • The UOR catalyst with high activity and stability was constructed by a simple method. • The required voltage of the Ni/NiO–NiWO 4 -2 for UOR is 1.3749 V@10 mA cm−2 in alkaline medium. • W doping effectively weakens the poisoning of Ni3+ active components by intermediates. • W doping effectively reduces the energy barrier of UOR verified by DFT calculation. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is an important half-reaction of many actual processes, which has the slow kinetics of four-electron process. Interface engineering as an effective method can accelerate the slow kinetics of oxygen evolution reaction. In this paper, CoSe 2 –MoSe 2 porous nanosheet arrays with heterostructures were synthesized on carbon cloth by ion exchange and vapor phase selenization using Co-MOF as template. Due to the porous two-dimensional structure, the electron diffusion path is shortened and the self-supporting electrode has excellent conductivity. When catalyzing OER in 1 M KOH solution, the CoSe 2 –MoSe 2 delivers an overpotential of 278 mV at 10 mA cmm2, and Tafel slope of 61.2 mV dec−1, making catalytic activity a better result than commercial RuO 2. In addition, the decay of the catalytic activity is negligible after 24 h of continuous electrolysis. This work provides a method for the design of porous bimetallic selenide self-supporting oxygen evolution electrocatalysts. [Display omitted] • The CoSe 2 –MoSe 2 /CC was synthesized by ion exchange and gas-phase selenization. • The CoSe 2 –MoSe 2 /CC catalyst has porous nanosheet array morphology. • Porous CoSe 2 –MoSe 2 /CC exhibits excellent OER catalytic activity. [ABSTRACT FROM AUTHOR]

Due to the excellent quantum conversion and spectral response characteristics of the AlGaN photocathode, it has become the most promising III-V group semiconductor photocathode in solar-blind signal photoconversion devices in the ultraviolet band. Herein, the influence factors of the time-resolved characteristics of the AlGaN photocathode are researched by solving the photoelectron continuity equation and photoelectron flow density equation, such as the AlN/AlGaN interface recombination rate, AlGaN electron diffusion coefficient, and AlGaN activation layer thickness. The results show that the response time of the AlGaN photocathode decreases gradually with the increase in AlGaN photoelectron diffusion coefficient and AlN/AlGaN interface recombination rate, but the response time of the AlGaN photocathode gradually becomes saturated with the further increase in AlN/AlGaN interface recombination rate. When the thickness of the AlGaN photocathode is reduced from 250 nm to 50 nm, the response time of the AlGaN photocathode decreases from 63.28 ps to 9.91 ps, and the response time of AlGaN photocathode greatly improves. This study provides theoretical guidance for the development of a fast response UV detector. [ABSTRACT FROM AUTHOR]

We studied positive streamers with a 5 mm gap under 20–101 kPa pressure and 1%–31% O2 concentrations conditions using a 2D axisymmetric fluid model based on local field approximation. As the pressure decreases from 101 kPa to 20 kPa, the axial reduced electric field, the mean electron energy and the electron diffusion coefficient increase, which leads to the acceleration of the streamer propagation velocity and the increase of the streamer channel radius. The opposite change of ionization cross section and gas molecular density caused by the decrease of pressure leads to the non-monotonic change of the peak of net ionization rate. At medium-low pressure, there is a wider ionization region at the streamer head. As the O2 concentration decreases from 31% to 1% in N2/O2, the streamer propagation velocity decreases. When the O2 concentration drops to 1%, the streamer velocity decreases with a descent gradient of nearly 4 times, compared to 11% O2. Based on the space charge effect and chemical reaction rate, a possible mechanism is proposed to explain the abrupt change in the streamer velocity. [ABSTRACT FROM AUTHOR]

The photocatalyst would be a promising method for easing energy crisis and improving ecological environment. However, the high photo-generated carrier recombination and photocorrosion would be the core issue for restricting its actual applications, and can be ameliorated by the surface heterojunction modification. The Bi 2 WO 6 /CdS hollow core-shell S-scheme nano-heterojunction is synthesized via chemical-hydrothermal method. Bi 2 WO 6 /CdS nano-heterojunction (Bi 2 WO 6 /CdS-3) exhibits signally enhanced visible light HER (∼1250.33 μmol g−1·h−1)/degradation ciprofloxacin (∼85.0%/24 min, ∼0.07580 min−1) than monomer CdS (∼36/5.9-folds) and monomer Bi 2 WO 6 (∼50/12.7-folds), including decent stability (average HER ∼1225.28 μmol∙g−1 h−1 and photodegradation ∼83.3%). It mainly attributes to the Bi 2 WO 6 /CdS S-scheme heterojunction with appropriate potential gradient can promote interface carrier driving to optimize efficiency and provide strong stronger reduction/oxidation, including increasing carrier transport, extending carrier lifetime, and reducing recombination. Additionally, the hollow core-shell structure can increase numerous active sites for decreasing overpotential and promoting electron diffusion, and improve solar efficiency (multiple reflections), including shorting carrier pathway for photocorrosion optimization, while enhancing structural stability. [Display omitted] • S-scheme heterojuction optimize carrier efficiency via greater Fermi levels gradient. • S-scheme heterojuction provide strong stronger reduction/oxidation. • Hollow core-shell structure increase active sites to promote electron diffusion. • Template auxiliary can regulate size accurately and form hollow structure easily. [ABSTRACT FROM AUTHOR]

Head-on collision of the two small-amplitude electron-acoustic (EA) solitons is studied in an unmagnetized collisionless plasma in the presence of superthermal (hot) trapped electrons. For this purpose, using a well-known extended Poincare–Lighthill–Kuo (PLK) method, a pair of the trapped Korteweg–de Vries (tKdV) equations is derived to investigate the soliton trajectories and phase shifts. The latter are found dependent on amplitudes of the interacting solitons, effectively altering with hot-electron superthermality and plasma parameters. Typical parameters for the electron diffusion region (EDR) and day-side auroral zone have been selected to examine the impact of hot-electron superthermality, trapping parameter, hot-to-cold electron number density ratio, and cold-to-hot electron temperature ratio on the profiles of potential excitations and phase shifts of interacting solitons. It is found that phase speed of the EA waves becomes altered by varying the κ – parameter, strongly modifying the nonlinearity and dispersive coefficients in a superthermal trapped plasma. However, particle trapping phenomenon does not affect the linear phase speed but introduces a fractional nonlinearity in the tKdV equations of two interacting solitons. The impact of the adiabatic and isothermal pressures is also highlighted to show new modifications in the propagation characteristics of two interacting solitons. [ABSTRACT FROM AUTHOR]

For dye-sensitized solar cells (DSSC), the material properties and design parameters of their photoanodes have a more significant impact on the performance of DSSCs. In order to investigate this issue in depth, this paper adopts numerical simulation to explore the detailed impact of change in the photoanode structure on the performance of DSSC. However, the current mathematical model is not comprehensive enough and the prediction accuracy is low. Therefore, based on the theory of photoelectron transfer and Lambert Beer's law, this paper introduces the influence of porosity on electron diffusion coefficient into the mathematical model of DSSC using constant stacking method and variable stacking method, and establishes a more comprehensive and accurate electron transfer model. This model can deeply analyze the impact of changes in the structure parameters of the photoanode on the performance of DSSC. The performance of DSSC under different pore volumes, electron lifetime, SnO2 coating thickness, and specific surface area were simulated through numerical simulation. The results show that as the pore volume of SnO2 thin films increases, the short-circuit current density of solar cells gradually decreases, while the open circuit voltage shows an increasing trend, leading to a gradual decrease in photoelectric conversion efficiency. When the pore volume reaches 0. 10 cm3 / g, its photoelectric conversion efficiency reaches 5. 16%. Therefore, while ensuring the rigidity of the battery, reducing the pore volume of SnO2 as much as possible is beneficial for improving the absorption coefficient and diffusion coefficient. The improvement of these two parameters is conducive to the overall performance of DSSC. At the same time, the extension of electron lifetime will bring about an increase in the short-circuit current density and open circuit voltage of solar cells, thereby improving the photoelectric conversion efficiency. When the electron lifetime reaches 200 ms, its photoelectric conversion efficiency reaches 5.82%. This study provides strong theoretical guidance for optimizing the photoanode structure and improving the photoelectric performance of DSSC through detailed numerical simulation analysis, which helps to further promote the research and application of dye sensitized solar cells. [ABSTRACT FROM AUTHOR]

We study the geomagnetic storm of 9 October 2012, where it had been generally accepted that the resulting prominent outer radiation belt electron acceleration throughout the storm is due to whistler‐mode chorus waves. This storm has been studied previously by two‐dimensional Fokker–Planck numerical simulations with data‐driven quasi‐linear (QL) diffusion rates. However, possible nonlinear (NL) resonant interaction effects on electron flux dynamics haven't been looked at yet. This study aims to fill this gap by demonstrating that theory‐informed rescaling of QL diffusion rates accounting for contributions of NL resonant interactions helps to reproduce better observed increase of electron fluxes by diffusion simulations. We use machine learning, uncertainty quantification (UQ), physics‐perturbed ensemble of VERB simulations and Van Allen Probes observations to identify optimal rescaling of quasi‐linear diffusion rates. Plain Language Summary: Characterizing and understanding the rapid enhancements of relativistic electrons, which can damage Earth‐orbiting satellites, is critical for predicting the near‐Earth radiation environment and is an integral part of space weather. Electromagnetic wave‐particle interactions provide the dominant mechanism for changes in the outer radiation belt structure. For small wave amplitudes and a broad wave spectrum, such interactions can be described by the quasi‐linear theory, leading to the Fokker‐Planck diffusion equation for the phase space density of electrons. However, for high amplitude waves, non‐linear interaction effects can also change the distributions of energetic electrons in the heart of the outer radiation belt and must be accounted for. In this study, a nonlinear description of electron dynamics is enabled by theory‐informed rescaling of quasi‐linear diffusion coefficients in the Fokker‐Planck diffusion equation to accurately capture the rapid acceleration of electrons during the geomagnetic storm of 9 October 2012. Key Points: Evidence of nonlinear wave‐particle resonant interaction effects for electron flux dynamics in the geomagnetic storm of 9 October 2012Theory‐informed rescaling of quasi‐linear diffusion rates in VERB simulations helps to reproduce better observed increase of electron fluxesUncertainty quantification, machine learning and physics‐perturbed ensemble of VERB simulations enables to identify optimal rescaling factor [ABSTRACT FROM AUTHOR]

2D MOFs grown on 1D ZIF-67 modified carbon nanofibers with hierarchical heterostructures and bamboo derived carbon for high-performance solid-state asymmetric supercapacitors. [Display omitted] • A MOFs grown on ZIF-67 modified carbon nanofibres (CCNF) was fabricated, presenting a 2D/1D hierarchical heterostructure. • Hierarchical heterostructures contribute to short ion/electron diffusion pathways, rich active sites, and high activities. • CCNF-20@MOF dominated by a diffusion-controlled energy storage, displayed a specific capacity of 361.50 C g−1. • A bamboo derived carbon was prepared as the negative electrode for the solid-state asymmetric supercapacitor. • The device delivered the maximum energy density of 38.89 Wh kg−1, which could support for the luminescence of LED. In this paper, a 2 dimensional (2D) metal–organic frameworks (MOFs) nanosheets grown on 1D ZIF-67 modified carbon nanofibers (CNFs) was designed and fabricated with a hierarchical heterostructure. The hierarchical 2D/1D MOFs/CCNF offers rich electrochemical active sites and favorable ion/electron diffusion pathways. The synergistic effect of Co, CNFs and MOFs from heterostructures contributes to superb electrochemical activities. Benefiting from the hierarchical heterostructures optimized by the mass ratio of ZIF-67/PAN and CCNF/NiMOF as well as the type of substrates, CCNF-20@MOF showed a specific capacity of 361.50 C g−1 at 0.5 A g−1, whose charge storage mechanism is dominated by diffusion control. Meanwhile, a bamboo-derived carbon material (BBC) was designed in the solid-state asymmetric supercapacitor (CCNF-20@MOF//BBC). The device exhibited an energy density of 38.89 Wh kg−1 at the power density of 800.02 W kg−1 and excellent cycling stability, that exceed many MOFs based devices. Moreover, it could be successfully used for LED light-emitting, demonstrating a good application prospect. This work provides a feasible strategy for the improved performance of MOFs and CNFs based materials in the field of energy storage. [ABSTRACT FROM AUTHOR]

RuCo alloy nanoparticles confined in hollow spherical structure (hcp-RuCo@C) was fabricated by impregnation and pyrolysis strategies. Studies demonstrate that alloying-induced d - d electronic interaction significantly optimize the adsorption energies of H and OH species, which enabled them to exhibit impressive HOR activity and resistance to CO poisoning. [Display omitted] • RuCo alloy nanoparticles is fabricated by impregnation and pyrolysis strategies. • The hollow mesoporous structure facilitates ion diffusion and electron transport. • The hcp-RuCo@C exhibits good HOR activity and resistance to CO poisoning. • Alloying-induced d - d electronic interaction optimizes the HBE and OHBE, promoting the vital Volmer step. Bimetallic alloys hold exceptional promise as candidate materials because they offer a diverse parameter space for optimizing electronic structures and catalytic sites. Herein, we fabricate ruthenium-cobalt alloy nanoparticles uniformly dispersed within hollow mesoporous carbon spheres (hcp-RuCo@C) via impregnation and pyrolysis strategies. The intriguing hollow mesopore structure of hcp-RuCo@C facilitates efficient contact between active sites and reactants, thereby accelerating hydrogen oxidation reaction (HOR) kinetics. As anticipated, the hcp-RuCo@C showcases remarkable exchange current density and mass activity of 3.73 mA cm−2 and 2.8 mA μ g R u - 1 , respectively, surpassing those of commercial Pt/C and documented Ru-based electrocatalysts. Notably, hcp-RuCo@C demonstrates robust resistance to 1000 ppm CO, a trait lacking in Pt/C catalysts. Comprehensive experimental results reveal that the alloying-induced d - d electronic interactions between Ru and Co species significantly optimizes hydrogen binding energy (HBE) and hydroxide binding energy (OHBE). This optimization promotes the vital Volmer step, ameliorating the alkaline HOR properties of hcp-RuCo@C. [ABSTRACT FROM AUTHOR]

Colossal permittivity (CP, Ɛ r) ceramics are highly desired for promising applications in modern electronic industry. However, actual applications of CP ceramics were seriously limited by large dielectric loss (tan δ), strong temperature/frequency/electric field dependence, and resistance degradation behavior. Here, we proposed a novel strategy to inhibit the diffusion of oxygen vacancies to obtain a CP Sr 0.979 Y 0.014 TiO 3 (SYT14) ceramic with a combination of low tan δ and high insulation resistivity (ρ), by MgO addition, due to the formation of [ M g T i ″ − V O • • ] , [ M g T i ″ − 2 Y S r • ] and highly insulated phase at the grain boundary. SYT14-7 M (x = 0.7 wt% MgO) ceramic has excellent comprehensive properties, such as, Ɛ r is 28156, tan δ is 0.0136, and ρ is 7.02 × 1011 Ω cm. The phenomenon of "resistance oscillation" reflects the active degree of oxygen vacancy diffusion behavior. The highly insulated phase forming at the grain boundary can significantly inhibit oxygen vacancy diffusion and electron migration. The temperature range related to active oxygen vacancy diffusion is between 400 and 500 °C. [ABSTRACT FROM AUTHOR]

Colloidal nanorods based on CdS or CdSe, functionalized with metal particles, have proven to be efficient catalysts for light-driven hydrogen evolution. Seeded CdSe@CdS nanorods have shown increasing performance with increasing rod length. This observation was rationalized by the increasing lifetime of the separated charges, as a large distance between holes localized in the CdSe seed and electrons localized at the metal tip decreases their recombination rate. However, the impact of nanorod length on the electron-to-tip localization efficiency or pathway remained an open question. Therefore, we investigated the photo-induced electron transfer to the metal in a series of Ni-tipped CdSe@CdS nanorods with varying length. We find that the transfer processes occurring from the region close to the semiconductor–metal interface, the rod region, and the CdSe seed region depend in different ways on the rods' length. The rate of the fastest process from excitonic states generated directly at the interface is independent of the rod length, but the relative amplitude decreases with increasing rod length, as the weight of the interface region is decreasing. The transfer of electrons to the metal tip from excitons generated in the CdS rod region depends strongly on the length of the nanorods, which indicates an electron transport-limited process, i.e., electron diffusion toward the interface region, followed by fast interface crossing. The transfer originating from the CdSe excitonic states again shows no significant length dependence in its time constant, as it is probably limited by the rate of overcoming the shallow confinement in the CdSe seed. [ABSTRACT FROM AUTHOR]

Femtosecond laser inscriptions in optical media current offer the most reliable optical technology for processing of transparent materials, among which is the laser micromachining technology. In this process, the nonlinearity of the transparent medium can be either intrinsic or induced by multiphoton ionization processes. In this work, a generic model is proposed to describe the dynamics of femtosecond laser inscription in transparent materials characterized by a saturable nonlinearity. The model takes into account multiphoton ionization processes that can induce an electron plasma of inhomogeneous density and electron diffusions. The mathematical model is represented by a one-dimensional complex Ginzburg–Landau equation with a generalized saturable nonlinearity term in addition to the residual nonlinearity related to multiphoton ionization processes, coupled to a rate equation for time evolution of the electron plasma density. Dynamical properties of the model are investigated focusing on the nonlinear regime, where the model equations are transformed into a set of coupled first-order nonlinear ordinary differential equations, which are solved numerically with the help of a sixth-order Runge–Kutta algorithm with a fixed time step. Simulations reveal that upon propagation, spatiotemporal profiles of the optical field and of the plasma density are periodic pulse trains, the repetition rates and amplitudes of which are increased with an increase of both the multiphoton ionization order and the saturable nonlinearity. When electron diffusions are taken into account, the system dynamics remains qualitatively unchanged; however, the electron plasma density gets strongly depleted, leaving almost unchanged the amplitude of pulses composing the femtosecond laser soliton crystals. [ABSTRACT FROM AUTHOR]

Functionalized nanoparticles (NPs) are complex objects present in a variety of systems ranging from synthetic grafted nanoparticles to viruses. The morphology and number of the decorating groups can vary widely between systems. Thus, the modeling of functionalized NPs typically considers simplified spherical objects as a first-order approximation. At the nanoscale label, complex hydrodynamic interactions are expected to emerge as the morphological features of the particles change, and they can be further amplified when the NPs are confined or near walls. Direct estimation of these variations can be inferred via diffusion coefficients of the NPs. However, the evaluation of the coefficients requires an improved representation of the NPs morphology to reproduce important features hidden by simplified spherical models. Here, we characterize the passive transport of free and confined functionalized nanoparticles using the Rigid Multi-Blob (RMB) method. The main advantage of RMB is its versatility to approximate the mobility of complex structures at the nanoscale with significant accuracy and reduced computational cost. In particular, we investigate the effect of functional groups' distribution, size, and morphology over nanoparticle translational and rotational diffusion. We identify that the presence of functional groups significantly affects the rotational diffusion of the nanoparticles; moreover, the morphology of the groups and number induce characteristic mobility reduction compared to non-functionalized nanoparticles. Confined NPs also evidenced important alterations in their diffusivity, with distinctive signatures in the off-diagonal contributions of the rotational diffusion. These results can be exploited in various applications, including biomedical, polymer nanocomposite fabrication, drug delivery, and imaging. [ABSTRACT FROM AUTHOR]

Wide-bandgap semiconductors are regarded as preferred materials for preparing semiconductor conversion devices in betavoltaic batteries due to their high theoretical conversion efficiency (ηc). However, there are a few comprehensive analytical studies on why the experimental values of ηc are generally much lower than the theoretical limit of ηc (ηc-limit) and how to improve ηc and its stability. In this work, combined with the energy deposition distributions of Ti3H2, 63Ni, and 147Pm2O3 radioactive sources in SiC obtained from Monte Carlo simulations, a multi-physical mechanism, multi-parameter coupling numerical model was established. This model can comprehensively analyze the output characteristics of betavoltaic batteries under the influence of actual device structural and material parameter changes. Our results show that changes in structural and material parameters cause significant variations in the collection efficiency (Q) of the radiation-generated electron–hole pair (RG-EHP). Considering structural parameters are easy to control, instabilities in actual SiC material parameters, which include electron diffusion length (Ln), hole diffusion length (Lp), and surface recombination velocity (S), are the main reason that ηc fluctuates significantly and is generally far lower than ηc-limit. Due to differences in the distribution of RG-EHP produced by different radioactive sources in SiC, the dominant parameters causing ηc fluctuations differ. By analyzing differences in recombination loss mechanisms under different radioactive sources, the device structures were designed in a targeted manner to make ηc closer to ηc-limit. Meanwhile, when the SiC material quality fluctuates, the stability of ηc increases by 58.5%, 35.3%, and 48.2% under Ti3H2, 63Ni, and 147Pm2O3, respectively. [ABSTRACT FROM AUTHOR]

Anionic redox chemistry is now viewed as the effective paradigm of improving the capacity of layered oxide materials in Sodium‐ion battery. In this study, O3‐type layered oxide NaLi0.18Co0.23Ru0.59O2 (NLCR) with O redox ability is successfully synthesized via a facile solid‐state synthesis method. By manipulating the calcinate atmosphere with air and argon (sort by NLCR‐Air NLCR‐Ar respectively), a large amount of O vacancy is introduced in the NLCR‐Air cathode. NLCR‐Air with sufficient O vacancy exhibited superior rate performance which showed 87.7% capacity retention after 1000 cycles at 20 C. Both NLCR‐Air and NLCR‐Ar showed activation of O redox properties which is supported by the soft X‐ray absorption spectroscopy (sXAS). Nevertheless, the in‐situ X‐ray diffraction and sXAS studies disclosed the O vacancy can promote the reversible phase transition and effectively suppress the irreversible O redox upon cycling. These are further supported by theoretical study which suggested a fast kinetic of Na diffusion and less electron agglomeration around the O atom for NLCR‐Air with O vacancy.The research proposed a modification strategy with extraordinary reversible O redox property within O3‐type layered cathode and offered a novel insight into understanding the anionic redox mechanism thus provide guidance of material design advanced energy storage systems. [ABSTRACT FROM AUTHOR]

The problem of calculating kinetic characteristics during electron drift in inert gases in a wide range of the reduced electric field strength: 0.001 Td < E/N < 10 000 Td is considered. For the case of a weak field E/N < 0.01 Td, there is little reference data, and the drift velocity, average energy, longitudinal and transverse diffusion coefficients and ionization coefficient for the cases of a weak field and a moderately strong field E/N < 100 Td were calculated using the method of dynamics of many particles involving collisions in accordance with the Monte Carlo procedure. For the cases of strong and superstrong fields 100 Td < E/N < 10 000 Td, the results of calculations for two models of electron departure from the system were considered and analyzed for the first time: (1) an avalanche model with multiplication; (2) a model with the most energetic electron in the system leaving the wall during the act of ionization or transition to the escape mode. Taking into account the appearance of new electrons in the system during ionization events under stationary current conditions made it possible to include the departure of electrons from the system to the wall with the determination of its potential into the consideration and, by analogy with the ionization coefficient, to introduce the definition of the electron runaway coefficient. For these two models, tabulated values of the electron runaway coefficient were obtained. An analysis and comparison of the calculation results with the table data was carried out. In addition, we present analytical approximations of the elastic and inelastic cross sections of electron–atom collisions depending on the collision energy that we obtained based on an analysis of the available theoretical and experimental data. They have physically reasonable asymptotics and can be recommended by us for widespread use. [ABSTRACT FROM AUTHOR]

Photocatalytic H2 evolution has been regarded as a promising technology to alleviate the energy crisis. Designing graphitic carbon nitride materials with a large surface area, short diffusion paths for electrons, and more exposed reactive sites are beneficial for hydrogen evolution. In this study, a facile method was proposed to dope P into a graphitic carbon nitride framework by calcining melamine with 2-aminoethylphosphonic acid. Meanwhile, PCN nanosheets (PCNSs) were obtained through a thermal exfoliation strategy. Under visible light, the PCNS sample displayed a hydrogen evolution rate of 700 μmol·g−1·h−1, which was 43.8-fold higher than that of pure g-C3N4. In addition, the PCNS photocatalyst also displayed good photostability for four consecutive cycles, with a total reaction time of 12 h. Its outstanding photocatalytic performance was attributed to the higher surface area exposing more reactive sites and the enlarged band edge for photoreduction potentials. This work provides a facile strategy to regulate catalytic structures, which may attract great research interest in the field of catalysis. [ABSTRACT FROM AUTHOR]

We extend the previous three‐dimensional (3D) empirical reconstruction (ER) model for a set of ideal magnetohydrodynamics (MHD) constraints into a resistive MHD 3D ER model that includes additional resistive MHD constraints and additional measurements from NASA's Magnetospheric Multiscale (MMS) mission. The same form of a stochastic optimization algorithm is used as in the previous ideal MHD 3D ER model to directly minimize the loss function that includes a few more highly nonlinear terms characterizing the model‐measurement differences and the model departures from physical constraints. The resistive MHD 3D ER model is applied to three regions of MMS measurements that correspond to direct sampling of an electron diffusion region (EDR), a region adjacent to the EDR, and one far away from the EDR. The reconstructed plasma and electromagnetic fields are of high quality in all three regions as measured by model‐measurement difference indices and physics‐based quality indicators. The reconstructed fields in the EDR provide us with a good view of the spatial configuration of the reconnection site. We specifically examine the effect of resistivity on energy exchange in the vicinity of the EDR. It was discovered that in the EDR, the energy exchange shows an exclusive and systematic one‐channel process between the plasma thermal energy and electromagnetic energy with the conversion rate highly correlated with the strength of the turbulent electromagnetic fields. In the other two regions away from the EDR, the energy exchange between the electromagnetic energy and the plasma thermal and kinetic energies shows rapidly‐varying and random characteristics. Key Points: An empirical reconstruction model for a resistive MHD has been developed for 3D plasma and electromagnetic fields by using a stochastic optimization method together with the MMS measurements in the magnetosphereThe reconstructed plasma and electromagnetic fields are of high quality as shown by the model‐measurement difference indices and physics‐based quality indicators that objectively measure the accuracy and quality of the reconstructed fieldsThe energy exchange in the electron diffusion region shows an exclusive and systematic one‐channel process between the plasma thermal energy and electromagnetic energy with the conversion rate highly correlated with the strength of the turbulent electromagnetic fields [ABSTRACT FROM AUTHOR]

Fundamental processes in plasmas act to convert energies into different forms, for example, electromagnetic, kinetic and thermal. Direct derivation from the Vlasov‐Maxwell equation yields sets of equations that describe the temporal evolution of magnetic, kinetic and internal energies in either the monofluid or multifluid frameworks. In this work, we focus on the main terms affecting the changes in kinetic energy. These are pressure‐gradient‐related terms and electromagnetic terms. The former account for plasma acceleration/deceleration from a pressure gradient, while the latter from an electric field. Although limited spatial and temporal deviations are expected, a statistical balance between these terms is fundamental to ensure the overall conservation of energy and momentum. We use in‐situ observations from the Magnetospheric MultiScale (MMS) mission to study the relationship between these terms. We perform a statistical analysis of those parameters in the context of magnetic reconnection by focusing on small‐scale Electron Diffusion Regions and large‐scale Flux Transfer Events. The analysis reveals a correlation between the two terms in the monofluid force balance, and in the ion force and energy balance. However, the expected relationship cannot be verified from electron measurements. Generally, the pressure‐gradient‐related terms are smaller than their electromagnetic counterparts. We perform an error analysis to quantify the expected underestimation of gradient values as a function of the spacecraft separation compared to the gradient scale. Our findings highlight that MMS is capable of capturing energy and force balance for the ion fluid, but that care should be taken for energy conversion terms based on electron pressure gradients. Key Points: We analyze energy and force balance in the monofluid and multifluid frameworks using MMS dataWe show that MMS is able to capture energy and force balance in the monofluid and ion fluid frameworksThe ratio of spacecraft separation to local gradient scale limits the proper estimation of electron pressure gradient terms [ABSTRACT FROM AUTHOR]

Chorus waves are intense electromagnetic emissions critical in modulating electron dynamics. In this study, we perform two‐dimensional particle‐in‐cell simulations to investigate self‐consistent wave‐particle interactions with oblique chorus waves. We first analyze the electron dynamics sampled from cyclotron and Landau resonances with waves, and then quantify the advection and diffusion coefficients through statistical studies. It is found that phase‐trapped cyclotron resonant electrons satisfy the second‐order resonance condition and gain energy from waves. While phase‐bunched cyclotron resonant electrons cannot remain in resonance for long periods. They transfer energy to waves and are scattered to smaller pitch angles. Landau resonant electrons are primarily energized by waves. For both types of resonances, advection coefficients are greater than diffusion coefficients when the wave amplitude is large. Our study highlights the important role of advection in electron dynamics modulation resulting from nonlinear wave‐particle interactions. Plain Language Summary: Wave‐particle interactions can modulate electron distributions through advection and diffusion. Previous studies focusing on advection and diffusion primarily relied on test particle simulations, which uses a simplified model of wave evolution. In this study, we perform self‐consistent simulations to investigate the wave‐particle interactions with chorus waves and quantify the advection and diffusion coefficients of resonant electrons. It is found that advection coefficients are greater than diffusion coefficients in both cyclotron and Landau resonances, indicating the significant role of nonlinear wave‐particle interactions. The quantification of advection and diffusion coefficients in a self‐consistent system is important for understanding and predicting the loss and energization processes in radiation belt electrons. This study complements previous diffusion models that regarded the evolution of electron dynamics in wave‐particle interactions as a slow diffusive process. Key Points: Electron advection and diffusion in wave‐particle interactions with chorus waves are investigated through self‐consistent simulationsThe second‐order time derivative of gyrophase angle is nearly zero for phase‐trapped electrons but is negative for phase‐bunched electronsThe advection and diffusion coefficients for cyclotron and Landau resonant electrons interacting with chorus waves are quantified [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) are considered as the ideal candidates for the next generation of electrochemical energy storage devices. The major challenges of anode lie in poor cycling stability and the sluggish kinetics attributed to the inherent large Na+ size. In this work, Bi nanosphere encapsulated in N‐doped carbon nanowires (Bi@N‐C) is assembled by facile electrospinning and carbonization. N‐doped carbon mitigates the structure stress/strain during alloying/dealloying, optimizes the ionic/electronic diffusion, and provides fast electron transfer and structural stability. Due to the excellent structure, Bi@N‐C shows excellent Na storage performance in SIBs in terms of good cycling stability and rate capacity in half cells and full cells. The fundamental mechanism of the outstanding electrochemical performance of Bi@N‐C has been demonstrated through synchrotron in‐situ XRD, atomic force microscopy, ex‐situ scanning electron microscopy (SEM) and density functional theory (DFT) calculation. Importantly, a deeper understanding of the underlying reasons of the performance improvement is elucidated, which is vital for providing the theoretical basis for application of SIBs. [ABSTRACT FROM AUTHOR]

Electromagnetic ion cyclotron (EMIC) waves are a key plasma mode affecting radiation belt dynamics. These waves are important for relativistic electron losses through scattering and precipitation into Earth's ionosphere. Although theoretical models of such resonant scattering predict a low‐energy cut‐off of ∼1 MeV for precipitating electrons, observations from low‐altitude spacecraft often show simultaneous relativistic and sub‐relativistic electron precipitation associated with EMIC waves. Recently, nonresonant electron scattering by EMIC waves has been proposed as a possible solution to the above discrepancy. We employ this model and a large database of EMIC waves to develop a universal treatment of electron interactions with EMIC waves, including nonresonant effects. We use the Green's function approach to generalize EMIC diffusion rates foregoing the need to modify existing codes or recompute empirical wave databases. Comparison with observations from the electron losses and fields investigation mission demonstrates the efficacy of the proposed method for explaining sub‐relativistic electron losses by EMIC waves. Plain Language Summary: Precipitation of energetic electrons from the equatorial magnetosphere to the Earth's ionosphere plays a crucial role in the dynamics of the radiation belt and ionosphere ionization. Such precipitation is primarily driven by wave‐particle interactions. However, accurately modeling these interactions requires precise knowledge of the electron energy ranges which is affected by different wave modes present in the equatorial magnetosphere. A notable challenge arises from the contradiction between model‐predicted energy ranges of electron precipitation by electromagnetic ion cyclotron (EMIC) waves and the energies observed by spacecraft during such precipitation events. By combining a new theoretical approach with detailed observational data sets of these waves, we successfully resolved this contradiction, offering a powerful tool for the simulation of electron precipitation driven by EMIC waves. Key Points: We provide a statistical model of nonresonant electron scattering by electromagnetic ion cyclotron wavesWe show the main wave and electron parametric regions where nonresonant effects can be important for electron precipitationWe derive an analytical approximation allowing generalization of the quasi‐linear diffusion rates including nonresonant effects [ABSTRACT FROM AUTHOR]

This paper utilizes the theory of quantum diffusion to analyze the electron probability and spreading width of a wavepacket on each layer in a two-dimensional (2D) coupled system with edge disorder, aiming to clarify the effects of edge disorder on the stability of the electron periodic oscillations in 2D coupled systems. Using coupled 2D square lattices with edge disorder as an example, we show that, the electron probability and wavepacket spreading width exhibit periodic oscillations and damped oscillations, respectively, before and after the wavepacket reaches the boundary. Furthermore, these electron oscillations exhibit strong resistance against disorder perturbation with a longer decay time in the regime of large disorder, due to the combined influences of ordered and disordered site energies in the central and edge regions. Finally, we numerically verified the universality of the results through bilayer graphene, demonstrating that this anomalous quantum oscillatory behavior is independent of lattice geometry. Our findings are helpful in designing relevant quantum devices and understanding the influence of edge disorder on the stability of electron periodic oscillations in 2D coupled systems. [ABSTRACT FROM AUTHOR]

Two modifications of Te2MoO7 oxide have been prepared by different synthetic methods. The crystal structure and composition have been studied by X‐ray diffraction analysis and X‐ray microanalysis. The phase of α‐Te2MoO7 has been synthesized by solid‐state reaction from ammonium salts and characterized by monoclinic structure with P21/c. The β‐Te2MoO7 compound has been formed in hydrothermal conditions and has amorphous nature. The thermal behavior of β‐Te2MoO7 modification is characterized by the phase transition into α‐form, however after melting the amorphous state has restored. The electron structure has been investigated experimentally by X‐ray photoelectron spectroscopy and UV‐vis diffusion reflectance spectra and theoretically by approximation using atomic electronegativity. Despite the same composition, the band gap of β‐Te2MoO7 corresponds to visible light, whereas α‐Te2MoO7 adsorbs light in UV region. The both modifications are able to generate superoxide radicals in vacuum or air and hydroxyl radicals in water under irradiation. The HPLC‐MS analysis has shown the quite deep decomposition of dye and antibiotics by α‐Te2MoO7, whereas amorphous phase almost does not lead to any oxidation. [ABSTRACT FROM AUTHOR]

The Fe‐based anode of sodium‐ion batteries attracts much attention due to the abundant source, low‐cost, and high specific capacity. However, the low electron and ion transfer rate, poor structural stability, and shuttle effect of NaS2 intermediate restrain its further development. Herein, the Fe3O4/Fe/FeS tri‐heterojunction node spawned N‐carbon nanotube scaffold structure (FHNCS) was designed using the modified MIL‐88B(Fe) as a template followed by catalytic growth and sulfidation process. During catalytic growth process, the reduced Fe monomers catalyze the growth of N‐doped carbon nanotubes to connect the Fe3O4/Fe/FeS tri‐heterojunction node, forming a 3D scaffold structure. Wherein the N‐doped carbon promotes the transfer of electrons between Fe3O4/Fe/FeS particles, and the tri‐heterojunction facilitates the diffusion of electrons at the interface, to organize a 3D conductive network. The unique scaffold structure provides more active sites and shortens the Na+ diffusion path. Meanwhile, the structure exhibits excellent mechanical stability to alleviate the volume expansion during circulation. Furthermore, the Fe in Fe3O4/Fe heterojunction can adjust the d‐band center of Fe in Fe3O4 to enhance the adsorption between Fe3O4 and Na2S intermediate, which restrains the shuttle effect. Therefore, the FHNCS demonstrates a high specific capacity of 436 mAh g−1 at 0.5 A g−1, 84.7% and 73.4% of the initial capacities are maintained after 100 cycles at 0.5 A g−1 and 1000 cycles at 1.0 A g−1. We believe that this strategy gives an inspiration for constructing Fe‐based anode with excellent rate capability and cycling stability. [ABSTRACT FROM AUTHOR]

Methods of transmission and scanning electron microscopy are used to study premartenstic states and their relation to martensitic transformations in the alloys Cu–38 wt % Zn and Cu–39.5 wt % Zn with shape memory effect. Analysis of the observed diffusion scattering of electrons is carried out, including in situ experiments at heating and cooling and the defect condition of the internal substructure of austenite and martensite. The crystallographic models of martensitic transitions β2 → , β2 → , and β2 → are proposed based on the crystallographic data obtained in the premartensitic state. [ABSTRACT FROM AUTHOR]

Synchrotron X-ray nano computed tomography was employed to study how the microstructure changes during the co-sintering process of multi-layer ceramic capacitors (MLCC). MLCCs are composed of alternating Ni electrodes and BaTiO3 dielectric layers. When the thickness of the electrodes was reduced to submicron levels, on the order of a few particle diameters, it led to the development of defects in the inner electrodes, resulting in a loss of capacitance. The discontinuous electrode region contained circular holes and irregularly shaped channels. The creation of these gaps was linked to an increase in the characteristic length of the non-uniform electrode structure, which can be described as a coarsening process. The transformation of the electrode's shape through surface/ interface diffusion triggered the separation of the material connecting two holes. This separation was driven by instability induced by surface tension and stress, causing the material to form sharp points as it broke apart. These sharp points could potentially enhance the local electric field and lead to dielectric breakdown. An explanation was provided for the generation of defects arising from the arrangement of heterogeneous particles in the electrode layer. [ABSTRACT FROM AUTHOR]

The aim of this paper is to explore a Schrödinger equation that incorporates a higher‐order operator. Traditional models for electron dynamics have utilized a second‐order diffusion Schrödinger equation, where oscillatory behavior is achieved through complex domain formulations. Incorporating a higher‐order operator enables the induction of oscillatory spatial patterns in solutions. Our analysis initiates with a variational formulation within generalized spaces, facilitating the examination of solution boundedness. Subsequently, we delve into the oscillatory characteristics of solutions, drawing upon a series of lemmas originally applied to the Kuramoto–Sivashinsky equation, the Cahn–Hilliard equation, and other equations that employ higher‐order operators. Specific solution types, such as standing waves, are numerically investigated to illustrate the oscillatory spatial patterns. The discussion then extends to the theory of traveling waves to establish general conditions for positive solutions. A contribution of this work is the precise evaluation of a critical traveling wave speed, denoted as c∗$$ {c}&#x0005E;{\ast } $$, above which the first minimum remains positive. For values of the traveling wave speed c$$ c $$ significantly greater than c∗$$ {c}&#x0005E;{\ast } $$, the solutions can be entirely positive. [ABSTRACT FROM AUTHOR]

We report in situ observation of magnetic reconnection between magnetic flux rope (MFR) and magnetic hole (MH) in the magnetosheath by the Magnetospheric Multiscale mission. The MFR was rooted in the magnetopause and could be generated by magnetopause reconnection therein. A thin current sheet was generated due to the interaction between MFR and MH. The sub‐Alfvénic ion bulk flow and the Hall field were detected inside this thin current sheet, indicating an ongoing reconnection. An elongated electron diffusion region characterized by non‐frozen‐in electrons, magnetic‐to‐particle energy conversion, and crescent‐shaped electron distribution was detected in the reconnection exhaust. The observation provides a mechanism for the dissipation of MFRs and thus opens a new perspective on the evolution of MFRs at the magnetopause. Our work also reveals one potential fate of the MHs in the magnetosheath which could reconnect with the MFRs and further merge into the magnetopause. Plain Language Summary: Magnetic flux rope (MFR) is a kind of helical magnetic field structure that is frequently observed in the Earth's magnetosphere. At the dayside magnetopause, MFRs are generally generated by the reconnection of the Earth's intrinsic magnetic field and the interplanetary magnetic field, especially when the interplanetary magnetic field points southward. These MFRs tend to grow larger after they are expelled from the reconnection sites and then travel along the magnetopause, and ultimately disintegrate into the cusp. In this study, we provide another potential fate of these magnetopause MFRs. They can interact with the magnetosheath magnetic holes and dissipate through reconnection with multiple magnetic holes. Based on the Magnetospheric Multiscale observation, we provide direct evidence of reconnection between the MFR and the magnetic hole, which has a pivotal role in this scenario. Our results give new insights into the evolution of MFRs at the magnetopause and further the coupling between the solar wind and the Earth's magnetosphere. Key Points: First observation of magnetic reconnection between magnetic flux rope (MFR) and magnetic hole (MH) in the magnetosheathA thin current sheet with typical reconnection signatures was formed at the interface of MFR and MH due to their interactionAn elongated electron diffusion region was detected in the reconnection exhaust [ABSTRACT FROM AUTHOR]

Aluminum batteries employing organic electrode materials present an appealing avenue for sustainable and large‐scale energy storage. Nevertheless, conventional organic materials encounter limitations due to their restricted active sites, known instability, and sluggish redox kinetics. In this study, a redox‐active covalent organic framework supported by CNT is reported, enriched with substantial C═O groups, as an advanced cathode material for Al‐organic batteries. Theoretical simulation and ex situ analysis unveil the pivotal roles of C═O groups in effectively storing AlCl2+. As a result, Al batteries with the organic cathode exhibit a specific capacity of 290 mAh g−1 at 0.2 A g−1 and outstanding rate performance. Furthermore, it retains a reversible capacity of 170 mAh g−1 even after 32 000 cycles at 10 A g−1 and attains an energy density of 389 Wh kg−1. The remarkable performance stems not only from the abundant C═O and C─N groups enabling the storage of multiple AlCl2+ by the favorable pseudocapacitive process, but also from the synergistic interplay between the robust COF network and the conductive CNT channels that significantly enhances structural stability and accelerates ion/electron diffusion. This work stands to inspire further research in the pursuit of stable organic cathodes, fostering designs with plentiful accessible redox‐active sites to boost energy storage capabilities. [ABSTRACT FROM AUTHOR]

Sodium-ion batteries (SIBs) have received considerable attention in recent years. Anode material is one of the key factors that determine SIBs' electrochemical performance. Current commercial hard carbon anode shows poor rate performance, which greatly limits applications of SIBs. In this study, a novel vanadium-based material, SrV4O9, was proposed as an anode for SIBs, and its Na+ storage properties were studied for the first time. To enhance the electrical conductivity of SrV4O9 material, a microflower structure was designed and reduced graphene oxide (rGO) was introduced as a host to support SrV4O9 microflowers. The microflower structure effectively reduced electron diffusion distance, thus enhancing the electrical conductivity of the SrV4O9 material. The rGO showed excellent flexibility and electrical conductivity, which effectively improved the cycling life and rate performance of the SrV4O9 composite material. As a result, the SrV4O9@rGO composite showed excellent electrochemical performance (a stable capacity of 273.4 mAh g−1 after 200 cycles at 0.2 A g−1 and a high capacity of 120.4 mAh g−1 at 10.0 A g−1), indicating that SrV4O9@rGO composite can be an ideal anode material for SIBs. [ABSTRACT FROM AUTHOR]

Plasma Depletion Events (PDEs) are characterized by abrupt, localized reductions in ionospheric plasma density at least by an order of magnitude decrease. These events are observed over a limited range of altitudes, typically spanning a few tens of kilometers. We use Mars Atmosphere and Volatile Evolution spacecraft data to investigate the properties and possible formation mechanism of daytime PDEs, typically observed at altitudes above 250 km. We show, using two example events and statistical analysis, that the depletion events are associated with electrostatic fluctuations and increased electron temperatures. The events are further accompanied by enhanced fluxes of suprathermal electrons and light energetic ions. These are indicative of local plasma heating, possibly mediated by the electrostatic fluctuations. The heated plasma may eventually escape from the depletion region through the ambipolar diffusion. Plain Language Summary: The Martian ionosphere, consisting of ions and electrons, is embedded in the planet's thin atmosphere. Density variations in the ionosphere, occurring on both large and small scales, can significantly impact the atmospheric loss process on Mars. One particular type of these ionospheric anomalies involves sudden reductions in ion density, often by tenfold or more. Although we have a basic understanding of these depletion events, their detailed characteristics and origins are not yet fully understood. We use data from various instruments onboard the Mars Atmosphere and Volatile Evolution spacecraft to investigate these phenomena, particularly on the dayside. We find that these depletion events are accompanied by increased electron temperatures and enhanced electric field fluctuations, while the magnetic field remains virtually unchanged. These observations suggest localized plasma heating within the depleted region. Furthermore, the fluxes of energetic light ions (mostly protons) and electrons are increased during the events. This increase in energetic particles could potentially serve as the energy source driving the heating process. We propose that the depletion events form when the heated ionospheric plasma escapes from the heated region. Key Points: Large scale plasma density depletions in the Martian dayside ionosphere are linked with electrostatic fluctuationsIncreased electron temperatures, enhanced suprathermal electron fluxes, and energetic light ions are observed within the depleted regionsLocal plasma heating possibly drives electron escape, forming an ambipolar field and causing plasma depletions through ambipolar diffusion [ABSTRACT FROM AUTHOR]

We investigate the ground-state properties of N bosons with attractive zero-range interactions characterized by the scattering length a > 0 and confined to the surface of a sphere of radius R. We present the analytic solution of the problem for N = 2, mean-field analysis for N → ∞ , and exact diffusion Monte Carlo results for intermediate N. For finite N, we observe a smooth crossover from the uniform state in the limit a / R ≫ 1 (weak attraction) to a localized state at small a/R (strong attraction). With increasing N, this crossover narrows down to a discontinuous transition from the uniform state to a soliton of size ∼ R / N . The two states are separated by an energy barrier, tunneling under which is exponentially suppressed at large N. The system behavior is marked by a peculiar competition between space-curvature effects and beyond-mean-field terms, both breaking the scaling invariance of a two-dimensional mean-field theory. [ABSTRACT FROM AUTHOR]

In the Earth's magnetosheath (MSH), several processes contribute to energy dissipation and plasma heating, one of which is wave‐particle interactions between whistler waves and electrons. However, the overall impact of whistlers on electron dynamics in the MSH remains to be quantified. We analyze 18 hr of burst‐mode measurements from the Magnetospheric Multiscale (MMS) mission, including data from the unbiased magnetosheath campaign during February‐March 2023. We present a statistical study of 34,409 whistler waves found using automatic detection. We compare wave occurrence in the different MSH geometries and find three times higher occurrence in the quasi‐perpendicular MSH compared to the quasi‐parallel case. We also study the wave properties and find that the waves propagate quasi‐parallel to the background magnetic field, have a median frequency of 0.2 times the electron cyclotron frequency, median amplitude of 0.03–0.06 nT (30–60 pT), and median duration of a few tens of wave periods. The whistler waves are preferentially observed in local magnetic dips and density peaks and are not associated with an increased temperature anisotropy. Also, almost no whistlers are observed in regions with parallel electron plasma beta lower than 0.1. Importantly, when estimating pitch‐angle diffusion times we find that the whistler waves cause significant pitch‐angle scattering of electrons in the MSH. Key Points: Whistlers exist throughout the magnetosheath with higher occurrence in the quasi‐perpendicular geometry and in local magnetic field dipsWhistlers are observed in regions with electron beta above 0.1 and are not correlated with electron temperature anisotropyWhistlers cause significant pitch‐angle scattering of magnetosheath electrons [ABSTRACT FROM AUTHOR]

The intense electron‐scale current structures (ECSs) with the current density J ≥ 30 nA/m2 are often observed in the Plasma Sheet (PS) during high‐speed bulk flows. Using MMS observations we have analyzed 41 earthward and 37 tailward flow intervals and found 452 and 754 ECSs distributed over the PS region, respectively. Almost all ECSs are generated by high‐speed electron beams. The duration of ECSs is ≤1 s, and many of them have a half‐thickness L ≤ a few ρe (ρe is the gyroradius of thermal electrons). In such thin ECSs electrons become demagnetized and experience the dynamics like that observed in the electron diffusion region. Strong nonideal electric fields (E') associated with violation of frozen‐in condition for electrons are observed in the ECSs. This results in the intense energy conversion with J·E' up to hundreds pW/m3. The major part of the dissipating energy is transferred to electron heating and acceleration. We suggest that the ECSs are manifestations of kinetic‐scale turbulence driven by the high‐speed ion bulk flows. The inductive electric fields generated by the growing magnetic fluctuations accelerate electron beams which, in turn, generate the ECSs. The ECSs thinning during their evolution, probably, stops for L ≤ a few ρe. Further thinning leads to development of kinetic instability causing the current disruption and strong electric field generation. The last accelerates new electron beams which generate new ECSs in other locations. Thus, the life cycles of the ECSs contribute to energy cascade in turbulent plasma at electron kinetic scales. Key Points: Electron‐scale current structures (ECSs) with a few L/ρe thickness are observed in the plasma sheet during fast ion bulk flowsThe ECSs are mostly generated by demagnetized electrons experiencing the dynamics similar to that observed in electron diffusion regionIn the ECSs J·E' reaches the values typical for EDR, thus, they significantly contribute to the turbulent energy cascade at electron scales [ABSTRACT FROM AUTHOR]