Extranuclear Electrons Research Articles

Superconducting Electride Li9S with a Transition Temperature above the McMillan Limit.

An electride, characterized by unique interstitial anionic electrons (IAEs), offers promising avenues for modulating its superconductivity. The pressure-dependent coupling between IAEs and orbital electrons significantly affects the superconducting transition temperature (Tc). However, existing research has predominantly concentrated on pressures within 300 GPa. To advance the understanding, we propose investigating the Li-S system under ultrahigh pressure to unveil novel electride superconductors. Five stable Li-rich electrides with diverse IAE topologies, including one Li7S, three Li9S, and one Li12S phases, are identified through structural search calculations. Among the Li9S phases, in the C2/c phase (600 GPa), the IAEs are connected to the S atomic extra-nuclear electrons with the unconventional d orbital attribute due to the extreme pressure, while two low-pressure R-3 (25 GPa) and C2/m (400 GPa) phases have interconnected IAEs. Due to its unique IAE attributes, C2/c Li9S exhibits the highest Tc of 53.29 K at 600 GPa. Its superconductivity results from the coupling of the S d, Li p electrons, and IAEs with the low-frequency phonons associated with the attraction between IAEs and the Li-S framework. Our work enhances insights into IAEs within electrides and their role in facilitating superconductivity.

Oxygen octahedral void-confined iodine single-site RuO2 catalysts for water reduction

Iodine (I), with abundant extra-nuclear electrons and high electronegativity, can enhance the performance of catalysts by electronic tuning effects of I single-site. However, I atoms are always located at shallow surfaces of catalysts, leading to fast volatilization and subsequent poor catalytic stability. Herein, we conceive a single-site I doped RuO2 catalyst via heating RuI3 in air, wherein the I concentration gradually increases from shallow to deep surfaces. This ensures that partial I atoms are located in oxygen octahedral voids of RuO2 as single-site at deep surfaces of catalyst, avoiding I loss during catalysis. Impressively, I-introduction decreases the valence of Ru and strengthens the adsorption of *H on Ru actives, and then superior hydrogen evolution activity (14 mV @ 10 mA cm−2) is achieved in alkaline media. Additionally, both the confined effect of oxygen octahedral voids on I single atoms and stable I-O bonds make the catalyst durable for 50 h.

Electrical conductivity of binary magnesium alloys: Integrating first-principles and machine learning studies

The electrical conductivity is the fundamental physical property of Mg alloys and the basic information for the design of comprehensive high-performance Mg alloys. In this work, the electrical conductivity of 29 Mg-based binary alloys has been calculated using the first-principles methods and the main factors have been analyzed by machine learning. It is found that the electrical conductivity values of the binary alloys containing elements located in the s region and p region of the periodic table are bigger than others of alloys contain alloying elements in the f region and d region. The results of machine learning show that the difference ratio of volume (∆V/VMg), extra-nuclear electron configuration and difference of valence () play the main controlling role, followed by solid solubility and electronegativity of the alloying element. For solid solution elements in Mg-based binary alloys, the impact weight on the electrical conductivity is: difference ratio of volume > number of extra-nuclear electron vacancy > difference of valence.

Local electronic structure constructing of layer‐structured oxide cathode material for high‐voltage sodium‐ion batteries

AbstractAs the cyclable sodium ions' primary suppliers, O3‐type layer‐structured manganese‐based oxides are recognized as one of the most competitive cathode candidates for sodium‐ion batteries. Suffering from complex structural transformations and transition metal migration during the sodium intercalation/deintercalation process, particularly at high voltage, the energy density and lifespan cannot satisfy the increasing demand. The orbital and electronic structure of the octahedral center metal element plays an important role in maintaining the octahedral structural integrity and improving the Na+ diffusivity by the introduced heterogeneous [Me–O] (Me: transition metals) chemical bonding. Herein, inspired by the 4f and 5d orbital bonding possibility from the abundant configuration of extranuclear electrons and large ion radius, O3‐type Na[La0.01Ni0.3Mn0.54Cu0.1Ti0.05]O2 was synthesized with a nearly single crystal structure. Based on the experimental and computational results, the introduced heterogeneous [La–O] chemical bond with larger bond strength can not only ensure the stability of the lattice oxygen framework and the reversibility of oxygen redox but also optimize the oxygen local electronic structure resulting from La 5d and O 2p orbital mixing due to O 2p → La 5d charge transfer. It delivers an optimal electrochemical performance with a high energy density and cycling lifespan.

Engineering d-band center of cobalt active sites via dual coordination with nitrogen-doped carbon nanotube and Ti3C2Tx MXene toward electrocatalytic oxygen reduction for H2O2 production

Manipulating the selective adsorption of oxygen-containing species is crucial for tailoring the electrocatalyst to select dual-electron pathway in the oxygen reduction reaction (2e- ORR). Herein, dual-coordination electrocatalyst structure (Co-NCNT/MXene) is proposed based on the modulation of oxygenated species adsorption by coordination microenvironment at the interface of metal nanocatalysts. The Co-NCNT/MXene achieves excellent H2O2 selectivity (95.25 %), yield (162 mg L-1h−1) and Faraday efficiency (94.81 %) for ORR, surpassing the most Co-based-electrocatalysts. In-situ EPR techniques reveal the selective *OOH desorption dynamic process on Co-NCNT/MXene. Density functional theory calculations confirm that asymmetric coordination of Co nanoparticles by oxygen-terminated Ti3C2-MXene and NCNT modulates the delocalized state of Co extranuclear electrons, resulting in a reduction of the d-band center of Co, thus turning the adsorption energy of *OOH within the Co-NCNT/MXene interface towards a path more conducive to H2O2 electrosynthesis. In-situ H2O2 generated in the ORR is applied to achieve excellent degradation of organic pollutants.

Microwave-assisted exploration of the electron configuration-dependent electrocatalytic urea oxidation activity of 2D porous NiCo2O4 spinel

Urea holds promise as an alternative water-oxidation substrate in electrolytic cells. High-valence nickel-based spinel, especially after heteroatom doping, excels in urea oxidation reactions (UOR). However, traditional spinel synthesis methods with prolonged high-temperature reactions lack kinetic precision, hindering the balance between controlled doping and highly active two-dimensional (2D) porous structures design. This significantly impedes the identification of electron configuration-dependent active sites in doped 2D nickel-based spinels. Herein, we present a microwave shock method for the preparation of 2D porous NiCo2O4 spinel. Utilizing the transient on-off property of microwave pulses for precise heteroatom doping and 2D porous structural design, non-metal doping (boron, phosphorus, and sulfur) with distinct extranuclear electron disparities serves as straightforward examples for investigation. Precise tuning of lattice parameter reveals the impact of covalent bond strength on NiCo2O4 structural stability. The introduced defect levels induce unpaired d-electrons in transition metals, enhancing the adsorption of electron-donating amino groups in urea molecules. Simultaneously, Bode plots confirm the impact mechanism of rapid electron migration caused by reduced band gaps on UOR activity. The prepared phosphorus-doped 2D porous NiCo2O4, with optimal electron configuration control, outperforms most reported spinels. This controlled modification strategy advances understanding theoretical structure-activity mechanisms of high-performance 2D spinels in UOR.

A universal multifunctional rare earth oxide coating to stabilize high-voltage lithium layered oxide cathodes

The interfacial instability and bulk structural degradation of the high-voltage lithium layered oxide (LLO) cathodes make them suffer from severe capacity and voltage decay. Here, a universal multi-electron surface engineering strategy has been developed to conquer the root causes of the instability of LLO. The Gd in Gd2O3 with rich high-orbit extranuclear electrons is selected as an exemplary coating material to enhance the lithium storage properties of the LiNi0.6Co0.05Mn0.35O2 (NCM). On one hand, the Gd2O3 coating tunes the H1-H2 phase transition from a two-phase to quasi single-phase reaction and weakens the harmful H3 phase transition, minimizing the mechanical degradation of NCM. On the other hand, the Gd2O3 coating increases the activation energy of surface lattice oxygen loss and delays the phase transition temperature, inhibiting the oxidative decomposition of electrolyte and harmful interface phase transition and enhancing the thermal stability of the material. Thanks to these benefits, the Gd2O3-coated NCM experiences a weaker discharge median voltage decay after 100 cycles, and an 88.1% capacity retention rate could be achieved after 400 cycles. Furthermore, the generalizability of the multi-electron surface engineering strategy is certified by all rare earth metal oxides with boosted electrochemical performance for NCM.

Bonding Strength and Fracture Properties of Al (021)/Al2CuMg (001) Interface and Ag‐Doped Modification: A First‐Principles Study

The Al (021)/Al2CuMg (001) interface models based on experimental orientation relationship are constructed, the structure, work of adhesion, tensile strength, stacking fault energy (GSFE), doping modification, and electronic structure are investigated by first‐principles calculations. The CuMg‐terminated interface evolves into Al2‐terminated interface, which is consistent with experimental observations. Due to stronger bond strength, the M1‐type interface has higher work of adhesion (2.023 J m−2) and tensile strength (6.78 GPa) than these of M2‐type interface. Meanwhile, Ag doping can enhance the tensile strength of M2‐type interface to 6.63 GPa. By calculating the 2 d plot of GSFE, it is found that most slip directions for all interfaces are [110], [010], and [100] directions in Al2CuMg, respectively. Doping Ag atom improves the antislip ability of the M2‐type interface and further influences the tensile and slip properties of the Al/Al2CuMg interface. The charge density difference, electron localization function, and partial density of states demonstrate that the metallic and covalent bonds are mainly formed by Al‐2p orbitals at the interface, so the charge distribution of atoms in the vicinity of the interface is affected by the extranuclear electron of doping Ag atom.

Thermal Transport Properties of Diamond Phonons by Electric Field.

For the preparation of diamond heat sinks with ultra-high thermal conductivity by Chemical Vapor Deposition (CVD) technology, the influence of diamond growth direction and electric field on thermal conductivity is worth exploring. In this work, the phonon and thermal transport properties of diamond in three crystal orientation groups (<100>, <110>, and <111>) were investigated using first-principles calculations by electric field. The results show that the response of the diamond in the three-crystal orientation groups presented an obvious anisotropy under positive and negative electric fields. The electric field can break the symmetry of the diamond lattice, causing the electron density around the C atoms to be segregated with the direction of the electric field. Then the phonon spectrum and the thermodynamic properties of diamond were changed. At the same time, due to the coupling relationship between electrons and phonons, the electric field can affect the phonon group velocity, phonon mean free path, phonon–phonon interaction strength and phonon lifetime of the diamond. In the crystal orientation [111], when the electric field strength is ±0.004 a.u., the thermal conductivity is 2654 and 1283 , respectively. The main reason for the change in the thermal conductivity of the diamond lattice caused by the electric field is that the electric field has an acceleration effect on the extranuclear electrons of the C atoms in the diamond. Due to the coupling relationship between the electrons and the phonons, the thermodynamic and phonon properties of the diamond change.

Effect of germanium particle size on the negative air ion release and antimicrobial performances of germanium–polyamide 6 composite fibers

Germanium–polyamide 6 (Ge-PA6) fibers A, B and C containing germanium particles with sizes of D50 = 0.2, 2 and 7 μm were prepared using the melt spinning method. The effect of germanium particle size on the morphologies, mechanical properties, negative air ion (NAI) release and antimicrobial efficiencies of the two kinds of fibers were compared and analyzed. The NAI release and antimicrobial mechanisms of the Ge-PA6 fibers were also discussed. Results indicated that the germanium particles dispersed well inside the PA6 fiber substrate in the range of 1–3 wt%, and smaller particles help the fiber to obtain better diameter evenness and mechanical performance compared with larger ones. The stronger extranuclear electron activity and electrostatic voltage along the C-axis allow the fiber that contains smaller germanium particles to produce more NAIs compared to that containing larger particles. Some 780 and 1587 ions/m3 of NAIs could be produced by fiber A under the circumstance of 35°C and 40 N extrusion force when the germanium concentration was fixed at 3 wt%. The excellent NAI release property of the Ge-PA6 fiber endows it with inspiring antibacterial activity against S. aureus and C. albicans with a 12 h bacteriostasis rate of more than 90% at human body temperature. These results indicated Ge-PA6 fibers have great application potential in apparel and medical textiles.

Characteristics of secondary electron emission from few layer graphene on silicon (111) surface

As a typical two-dimensional (2D) coating material, graphene has been utilized to effectively reduce secondary electron emission from the surface. Nevertheless, the microscopic mechanism and the dominant factor of secondary electron emission suppression remain controversial. Since traditional models rely on the data of experimental bulk properties which are scarcely appropriate to the 2D coating situation, this paper presents the first-principles-based numerical calculations of the electron interaction and emission process for monolayer and multilayer graphene on silicon (111) substrate. By using the anisotropic energy loss for the coating graphene, the electron transport process can be described more realistically. The real physical electron interactions, including the elastic scattering of electron–nucleus, inelastic scattering of the electron–extranuclear electron, and electron–phonon effect, are considered and calculated by using the Monte Carlo method. The energy level transition theory-based first-principles method and the full Penn algorithm are used to calculate the energy loss function during the inelastic scattering. Variations of the energy loss function and interface electron density differences for 1 to 4 layer graphene coating GoSi are calculated, and their inner electron distributions and secondary electron emissions are analyzed. Simulation results demonstrate that the dominant factor of the inhibiting of secondary electron yield (SEY) of GoSi is to induce the deeper electrons in the internal scattering process. In contrast, a low surface potential barrier due to the positive deviation of electron density difference at monolayer GoSi interface in turn weakens the suppression of secondary electron emission of the graphene layer. Only when the graphene layer number is 3, does the contribution of surface work function to the secondary electron emission suppression appear to be slightly positive.

Effect of Mg(II), Mn(II), and Fe(II) doping on the mechanical properties and electronic structure of calcite

Calcite is one of the most important rock-forming minerals in the earth's crust, it is a very common mineral in nature and is widely used. Metal ions, such as Mg(II), Mn(II) and Fe(II), are often introduced into calcite as defects, which have a great influence on the crystal structure, mechanical properties and electronic structure of calcite. In order to understand the mechanism of the Mg(II), Mn(II), and Fe(II) doping of calcite, first-principles calculations are used to comprehensively study the various properties of calcite doped with different ions from an atomic-scale perspective. The calculation results show that the bonding characteristics of adjacent carbonate ions and layer spacing change after Mg-, Mn-, and Fe-doping, and the influence of Fe(II) on the calcite properties is the greatest, followed by those of Mn(II) and Mg(II). The influence of Fe(II) on the calcite properties is related to the ion radius and distribution of extra nuclear electrons. The elastic modulus of doped calcite decreases substantially, but the hardness of the material increases. The distribution of the density of states, energy band structure, and electrical conductivity of calcite doped with different ions also change significantly, which result in a variation in the electrical properties of calcite.

NiFexP@NiCo-LDH nanoarray bifunctional electrocatalysts for coupling of methanol oxidation and hydrogen production

NiFexP@NiCo-LDH/CC nanosheet core-shell nanoarrays electrocatalysts are prepared by electrodeposition and phosphating methods for relatively low potential production of H2 and value-added formate in methanol/water electrolysis systems. During the oxygen evolution reaction process, the over potential is 269 mA at the current density of 50 mA cm−2 and the Tafel slope is 97 mV dec−1. It also realizes the stable long-term electrocatalysis of methanol to formate under high current density and maintains a relatively high Faraday efficiency of 100%. Meanwhile, the energy saving is higher than 10% in the methanol oxidation and co-hydrogen production system that achieves great attention. The superior performance of NiFexP@NiCo-LDH/CC bifunctional electrocatalysts might be beneficial from the interaction to Ni and Fe bimetallic extranuclear electrons that exposes more active sites.

Effects of Mo single-doping and Mo-Al co-doping on ZnO transparent conductive films

Molybdenum (Mo) atoms with high valence (+6) can contribute four free electrons to zinc oxide (ZnO) crystals. Therefore, Mo is considered as potential dopant for improving the conductivity of ZnO films. In this paper, using the self-governing ceramic targets, ZnO thin films with different Mo single-doping concentrations (MZO) and Mo-Al co-doped concentrations (MAZO) were prepared by magnetron sputtering method. Combined with the material characterization method and the first principles, the effects of Mo single-doping and Mo-Al co-doping on the optical and electrical properties of ZnO thin films were analyzed. The experimental results show the carrier concentration and conductivity of ZnO films were effectively improved since the doping of Mo atoms increased the concentration of free electrons and decreased the defects of the ZnO lattice. However, the excessive single introduction of Mo6+ free electrons into ZnO lattice was prone to cause the refinement of MZO grain size and the emergence of more potential energy traps in the lattice, resulting in the increase of the absorption and the reduction of transmittance of MZO film. Nevertheless, Mo-Al co-doping made Mo and Al atoms play a synergistic role and effectively improve the optical properties of MAZO films. Astonishingly, with the increase of Mo doping concentration, Mo5+ appeared in MZO and MAZO films for the enhancement of the extranuclear electron localization. Furthermore, based on the electron band theory, it reveals that the Mo-4d impurity states appeared in the valence band of MZO and MAZO films and the valence band moved to a lower energy level, which led to the increase of absorption rate and decrease of transmittance of MZO film. Especially, as Mo-Al co-doping technology is adopted, the co-doping elements can make the impurity state act as a “springboard”, which is beneficial to the formation of photo-generated carriers, and improve the carrier concentration and the conductivity of MAZO films.

Efficient Electronic Modulation of g-C 3 N 4 Photocatalyst by Implanting Atomically Dispersed Ag 1 -N 3 for Extremely High Hydrogen Evolution Rates

Efficient Electronic Modulation of g-C ₃ N ₄ Photocatalyst by Implanting Atomically Dispersed Ag ₁ -N ₃ for Extremely High Hydrogen Evolution Rates

Rare Self-Luminous Mixed-Valence Eu-MOF with a Self-Enhanced Characteristic as a Near-Infrared Fluorescent ECL Probe for Nondestructive Immunodetection

Steady and efficient sensitized emission of Eu2+ to Eu3+ can be achieved through a rare mixed-valence Eu-MOF (L4EuIII2EuII). Compared with the sensitization of other substances, the similar ion radius and configuration of the extranuclear electron between Eu2+ and Eu3+ make sensitization easier and more efficient. The sensitization of Eu2+ to Eu3+ is of great assistance for the self-enhanced luminescence of L4EuIII2EuII, the longer luminous time, and the more stable electrochemiluminescence (ECL) signal. Simultaneously, L4EuIII2EuII possesses near-infrared (NIR) fluorescence of around 900 nm and a mighty self-luminous characteristic, which render it useful as a NIR fluorescent probe and as a luminophore to establish a NIR ECL biosensor. This NIR biosensor can greatly reduce the damage to the detected samples and even achieve a nondestructive test and improve the detection sensitivity by virtue of strong susceptibility and environmental suitability of NIR. In addition, the CeO2@Co3O4 triple-shelled microspheres further enhanced the ECL intensity due to two redox pairs of Ce3+/Ce4+ and Co2+/Co3+. The NIR ECL biosensor based on these strategies owns an ultrasensitive detection ability of CYFRA 21-1 with a low limit of detection of 1.70 fg/mL and also provides a novel idea for the construction of a highly effective nondestructive immunodetection biosensor.

Study on the growth patterns and simulated photoelectron spectroscopy of double vanadium atoms doped silicon clusters V2Sin(n ≤ 12) and their anions

Double vanadium atoms doped silicon clusters V2Sin (n ≤ 12) and their anionic species were investigated using the Perdew–Burke–Enzerhof (PBE) method combined with the ABCluster algorithm. The growth patterns of the most stable structures of neutral V2Sin and their anions are seen to derive from V2Sin-1 by absorbing a silicon atom. Their simulated photoelectron spectroscopy (PES), vertical detachment energy (VDE), adiabatic electron affinity (AEA), relative stability, and charge transfer were also calculated. With the exception of V2Si3, the average absolute errors of VDE and AEA are 0.12 and 0.165 eV compared with the available experimental values. Both neutral and anionic V2Si10 clusters possessed high stability and low chemical reactivity. Compared with neutral molecules, the 3d orbital of negatively charged ions had fewer electrons due to the arrangement of extra-nuclear electrons in anionic clusters belonging to the open-shell.

A review on thermal conductivity of magnesium and its alloys

Abstract This review summarizes recent researching works the thermal conductivity of Mg–Zn, Mg–Al, Mg–Mn and Mg–RE alloys. Solute atoms, heat treatment, deformation and temperature, which have significant influence on the thermal conductivity of magnesium alloys, are highlighted. For an individual solute atom, its effects on thermal conductivity are highly dependent on its chemical valence, radius and extra-nuclear electrons. The thermal conductivity of Mg alloys is decreased by solution treatment, but improved by aging and/or annealing treatments. As for the deformed Mg alloys, the thermal conductivity along transverse or normal direction is superior to that of along extrusion or rolling direction. We expect this review is helpful for those who are working on developing Mg alloys with superior thermal conductivity.

Proposal and Explanation of a New Periodic Table of the Chemical Elements

In the original periodic table of chemical elements, inert gas elements are arranged to the end of each cycle, and more phenomena can be explained by valency based on the combination of inorganic substances. In this paper, a new periodic table of elements is formulated based on retaining the original number of nuclear protons, neutrons and extra nuclear electrons, referring to the square correlation between the direct ratio of sphere area and radius, and some properties of elements. In the new table, it is considered that electrons fill spheres with radius of 1,2,3,4in turn, for example, one electron filling in the first cycle corresponds to one element of hydrogen (H); the radius of the second cycle is 2, sphere area is four times that of the first cycle, then four electrons can be filled, which correspond to four elements of He, Li, Be and B; the number element of the third cycle is square of 3, 9, and so on. The new table can better explain the distribution of certain elements, which is conducive to understanding the characteristics of various elements from another angle and expanding the insight into the micro world.

Effect of interlayer cations on exfoliating 2D montmorillonite nanosheets with high aspect ratio: From experiment to molecular calculation

Abstract In this work, the montmorillonite (MMT) with different interlayer ions (Na+ and Ca2+) were exfoliated to prepare high aspect ratio 2D montmorillonite nanosheets (MMTNS). The effect of interlayer cations was experimentally and theoretically studied through the atomic force microscope (AFM) and molecular simulation. Na-MMT could be more easily exfoliated to monolayer with the thickness of 0–1 nm compared to Ca-MMT, and the exfoliated Na-MMTNS have higher lateral diameter than Ca-MMTNS under the same condition, leading to that the Na-MMTNS with high aspect ratio can be more readily obtained. This observation was sufficiently interpreted by molecular dynamic simulation and first principles calculations including band structure, density of states, electron density difference and electron localization function. It is indicated that the interlayer binding energy of Na-MMT was weaker while its in-plane structure was stronger compared with Ca-MMT. The strong interacting force between interlayer Ca atoms and the in-plane atoms will cause structural failure after exfoliating Ca-MMT off to 2D nanosheets. It is suggested that the interaction between the extranuclear electrons of atoms in MMT layer and interlayer cations will affect the overall intensity and apparent exfoliation properties.