Construction of 3D porous Cu_(1.81)S/nitrogen-doped carbon frameworks for ultrafast and long-cycle life sodium-ion storage

Transition metal sulfides have great potential as anode mterials for sodium-ion batteries(SIBs)due to their high theoretical specific capacities.However,the inferior intrinsic conductivity and large volume variation during sodiation-desodiation processes seriously affect its high-rate and long-cyde performance,unbeneficial for the application as fast-charging and long-cycling SIBs anode.Herein,the three-dimensional porous Cu_(1.81)S/nitrogen-doped carbon frameworks(Cu_(1.81)S/NC)are synthesized by the simple and facile sol-gel and annealing processes,which can accommodate the volumetric expansion of Cu_(1.81)S nanoparticles and accelerate the transmission of ions and electrons during Na^(+)insertion/extraction processes,exhibiting the excellent rate capability(250.6 mA·g^(-1)at 20.0 A·g^(-1))and outstanding cycling stability(70% capacity retention for 6000 cycles at 10.0 A·g^(-1))for SIBs.Moreover,the Na-ion full cells coupled with Na_(3)V_(2)(PO_(4))_(3)/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g^(-1)at 5.0 A·g^(-1)and long-cycle performance with the 86.9% capacity retention at 2.0 A·g^(-1)after 750 cycles.This work proposes a promising way for the conversionbased metal sulfides for the applications as fast-charging sodium-ion battery anode.

Strain engineering of electronic and magnetic properties of Ga_2S_2 nanoribbons

Using first-principles calculations, we study the tailoring of the electronic and magnetic properties of gallium sulfide nanoribbons（Ga2S2NRs） by mechanical strain. Hydrogen-passivated armchair-and zigzag-edged NRs（ANRs and ZNRs）with different widths are investigated. Significant effects in band gap and magnetic properties are found and analyzed. First,the band gaps and their nature of ANRs can be largely tailored by a strain. The band gaps can be markedly reduced, and show an indirect-direct（I-D） transition under a tensile strain. While under an increasing compressive strain, they undergo a series transitions of I-D-I-D. Five strain zones with distinct band structures and their boundaries are identified. In addition,the carrier effective masses of ANRs are also tunable by the strain, showing jumps at the boundaries. Second, the magnetic moments of（ferromagnetic） ZNRs show jumps under an increasing compressive strain due to spin density redistribution,but are unresponsive to tensile strains. The rich tunable properties by stain suggest potential applications of Ga2S2 NRs in nanoelectronics and optoelectronics.

The manipulation of rectifying contact of Co and nitrogen-doped carbon hierarchical superstructures toward high-performance oxygen reduction reaction

Rational design and construction of oxygen reduction reaction(ORR)electrocatalysts with high activity,good stability,and low price are essential for the practical applications of renewable energy conversion devices,such as metal-air batteries.Electronic modification through constructing metal/semiconductor Schottky heterointerface represents a powerful strategy to enhance the electrochemical performance.Herein,we demonstrate a concept of Schottky electrocatalyst composed of uniform Co nanoparticles in situ anchored on the carbon nanotubes aligned on the carbon nanosheets(denoted as Co@N-CNTs/NSs hereafter)toward ORR.Both experimental findings and theoretical simulation testify that the rectifying contact could impel the voluntary electron flow from Co to N-CNTs/NSs and create an internal electric field,thereby boosting the electron transfer rate and improving the intrinsic activity.As a consequence,the Co@N-CNTs/NSs deliver outstanding ORR activity,impressive long-term durability,excellent methanol tolerance,and good performance as the air-cathode in the Zn-air batteries.The design concept of Schottky contact may provide the innovational inspirations for the synthesis of advanced catalysts in sustainable energy conversion fields.

Giant and controllable Goos—Hänchen shift of a reflective beam off a hyperbolic metasurface of polar crystals

We conduct a theoretical analysis of the massive and tunable Goos–Hänchen(GH) shift on a polar crystal covered with periodical black phosphorus(BP)-patches in the THz range. The surface plasmon phonon polaritons(SPPPs), which are coupled by the surface phonon polaritons(SPh Ps) and surface plasmon polaritons(SPPs), can greatly increase GH shifts.Based on the in-plane anisotropy of BP, two typical metasurface models are designed and investigated. An enormous GH shift of about-7565.58 λ_(0) is achieved by adjusting the physical parameters of the BP-patches. In the designed metasurface structure, the maximum sensitivity accompanying large GH shifts can reach about 6.43 × 10^(8) λ_(0)/RIU, which is extremely sensitive to the size, carrier density, and layer number of BP. Compared with a traditional surface plasmon resonance sensor, the sensitivity is increased by at least two orders of magnitude. We believe that investigating metasurface-based SPPPs sensors could lead to high-sensitivity biochemical detection applications.

Design of superconducting compounds at lower pressure via intercalating XH_(4)molecules(X=B,C,and N)into fcc lattices

Recently,many encouraging experimental advances have been achieved in ternary hydrides superconductors under high pressure.However,the extreme pressure required is indeed a challenge for practical application,which promotes a further exploration for high temperature(T_(c))superconductors at relatively low pressure.Herein,we performed a systematic theoretical investigation on a series of ternary hydrides with stoichiometry AX_(2)H_(8),which is constructed by interacting molecular XH_(4)(X=B,C,and N)into the fcc metal A lattice under low pressure of 0-150 GPa.We uncovered five compounds which are dynamically stable below 100 GPa,e.g.,AcB_(2)H_(8)(25 GPa),LaB_(2)H_(8)(40 GPa),RbC_(2)H_(8)(40 GPa),CSC_(2)H_(8)(60 GPa),and SrC_(2)H_(8)(65 GPa).Among them,AcB_(2)H_(8),which is energetically stable above 2.5 GPa,exhibits the highest Tcof 32 K at 25 GPa.The superconductivity originates mainly from the coupling between the electron of Ac atoms and the associated low-frequency phonons,distinct from the previous typical hydrides with H-derived superconductivity.Our results shed light on the future exploration of superconductivity among ternary compounds at low pressure.

Hyperbolic map unravels eight regions in temperature volatility regionalization of China's Mainland

Abrupt temperature volatility has detrimental effects on daily activities,macroeconomic growth,and human health.Predicting abrupt temperature volatility and thus diminishing its negative impacts can be achieved by exploring homogeneous regions of temperature volatility and analyzing the driving factors.To investigate the regionalization of temperature volatility in China's mainland,a network constructed by the cosine similarity of temperature volatility series from China's mainland was embedded in hyperbolic space.Subsequently,we partitioned the network on the hyperbolic map using the critical gap method and then found eight regions in all.Ultimately,a network of communities was constructed while the interaction among communities was quantified.This yields a perspective of temperature volatility regionalization that can accurately reflect factors including altitude,climate type,and the geographic location of mountains.Further analysis demonstrates that the regionalization in the hyperbolic map is distinct from provinces and has a realistic basis:communities in southwest China show strong correlations due to the temperature sensitivity to altitude,and communities in northern China show a convergence in the area of Dingxi,Gansu,mainly owing to the strong temperature sensitivity to climate types.As a consequence,node distributions and community divisions in the hyperbolic map can offer new insights into the regionalization of temperature volatility in China's mainland.The results demonstrate the potential of hyperbolic embedding of complex networks in forecasting future node associations in real-world data.

Application of different fiber structures and arrangements by electrospinning in triboelectric nanogenerators

In recent years,nanogenerators(NGs)have attracted wide attention in the energy field,among which triboelectric nanogenerators(TENGs)have shown superior performance.Multiple reports of electrospinning(ES)-based TENGs have been reported,but there is a lack of deep analysis of the designing method from microstructure,limiting the creative of new ES-based TENGs.Most TENGs use polymer materials to achieve corresponding design,which requires structural design of polymer materials.The existing polymer molding design methods include macroscopic molding methods,such as injection,compression,extrusion,calendering,etc.,combined with liquid-solid changes such as soluting and melting;it also includes micro-nano molding technology,such as melt-blown method,coagulation bath method,ES method,and nanoimprint method.In fact,ES technology has good controllability of thickness dimension and rich means of nanoscale structure regulation.At present,these characteristics have not been reviewed.Therefore,in this paper,we combine recent reports with some microstructure regulation functions of ES to establish a more general TENGs design method.Based on the rich microstructure research results in the field of ES,much more new types of TENGs can be designed in the future.

Design of weak current measurement system and research on temperature impact

A dedicated weak current measurement system was designed to measure the weak currents generated by the neutron ionization chamber.This system incorporates a second-order low-pass filter circuit and the Kalman filtering algorithm to effectively filter out noise and minimize interference in the measurement results.Testing conducted under normal temperature conditions has demonstrated the system's high precision performance.However,it was observed that temperature variations can affect the measurement performance.Data were collected across temperatures ranging from -20 to 70℃,and a temperature correction model was established through linear regression fitting to address this issue.The feasibility of the temperature correction model was confirmed at temperatures of -5 and 40℃,where relative errors remained below 0.1% after applying the temperature correction.The research indicates that the designed measurement system exhibits excellent temperature adaptability and high precision,making it particularly suitable for measuring weak currents.

Recent advances in fabrication and functions of neuromorphic system based on organic field effect transistor

The development of various artificial electronics and machines would explosively increase the amount of information and data,which need to be processed via in-situ remediation.Bioinspired synapse devices can store and process signals in a parallel way,thus improving fault tolerance and decreasing the power consumption of artificial systems.The organic field effect transistor(OFET)is a promising component for bioinspired neuromorphic systems because it is suitable for large-scale integrated circuits and flexible devices.In this review,the organic semiconductor materials,structures and fabrication,and different artificial sensory perception systems functions based on neuromorphic OFET devices are summarized.Subsequently,a summary and challenges of neuromorphic OFET devices are provided.This review presents a detailed introduction to the recent progress of neuromorphic OFET devices from semiconductor materials to perception systems,which would serve as a reference for the development of neuromorphic systems in future bioinspired electronics.

Seismic anisotropy and upper mantle dynamics in Alaska:A review of shear wave splitting analyses

Shear wave splitting(SWS)is regarded as the most effective geophysical method to delineate mantle flow fields by detecting seismic azimuthal anisotropy in the earth's upper mantle,especially in tectonically active regions such as subduction zones.The Aleutian-Alaska subduction zone has a convergence rate of approximately 50 mm/yr,with a trench length reaching nearly 2800 km.Such a long subduction zone has led to intensive continental deformation and numerous strong earthquakes in southern and central Alaska,while northern Alaska is relatively inactive.The sharp contrast makes Alaska a favorable locale to investigate the impact of subduction on mantle dynamics.Moreover,the uniqueness of this subduction zone,including the unusual subducting type,varying slab geometry,and atypical magmatic activity and composition,has intrigued the curiosity of many geoscientists.To identify different sources of seismic anisotropy beneath the Alaska region and probe the influence of a geometrically varying subducting slab on mantle dynamics,extensive SWS analyses have been conducted in the past decades.However,the insufficient station and azimuthal coverage,especially in early studies,not only led to some conflicting results but also strongly limited the in-depth investigation of layered anisotropy and the estimation of anisotropy depth.With the completion of the Transportable Array project in Alaska,recent studies have revealed more detailed mantle structures and characteristics based on the dense station coverage and newly collected massive seismic data.In this study,we review significant regional-and continental-scale SWS studies in the Alaska region and conclude the mantle flow fields therein,to understand how a geometrically varying subducting slab alters the regional mantle dynamics.The summarized mantle flow mechanisms are believed to be conducive to the understanding of seismic anisotropy patterns in other subduction zones with a complicated tectonic setting.

Synchronous implementation of optoelectronic NOR and XNOR logic gates using parallel synchronization of three chaotic lasers

The parallel synchronization of three chaotic lasers is used to emulate optoelectronic logic NOR and XNOR gates via modulating the light and the current. We deduce a logical computational equation that governs the chaotic synchronization, logical input, and logical output. We construct fundamental gates based on the three chaotic lasers and define the computational principle depending on the parallel synchronization. The logic gate can be implemented by appropriately synchronizing two chaotic lasers. The system shows practicability and flexibility because it can emulate synchronously an XNOR gate, two NOR gates, and so on. The synchronization can still be deteceted when mismatches exist with a certain range.

Probing structural and electronic properties of divalent metal Mg_(n+1) and SrMgn (n=2–12) clusters and their anions

Divalent metal clusters have received great attention due to the interesting size-induced nonmetal-to-metal transition and fascinating properties dependent on cluster size,shape,and doping.In this work,the combination of the CALYPSO code and density functional theory(DFT)optimization is employed to explore the structural properties of neutral and anionic Mg_(n+1) and SrMgn(n=2-12)clusters.The results exhibit that as the atomic number of Mg increases,Sr atoms are more likely to replace Mg atoms located in the skeleton convex cap.By analyzing the binding energy,second-order energy difference and the charge transfer,it can be found the SrMg9 cluster with tower framework presents outstanding stability in a studied size range.Further,bonding characteristic analysis reveals that the stability of SrMg9 can be improved due to the strong s-p interaction among the atomic orbitals of Sr and Mg atoms.

First-principles study of electronic structure and magnetic properties of Sr_(3)Fe_(2)O_(5) oxide

We investigate the electronic structure and magnetic properties of layered compound Sr_(3)Fe_(2)O_(5) based on firstprinciples calculations in the framework of density functional theory with GGA+U method.Under high pressure,the ladder-type layered structure of Sr_(3)Fe_(2)O_(5) is transformed into the infinite layered structure accompanied by a transition from G-type anti-ferromagnetic(AFM)insulator to ferromagnetic(FM)metal and a spin transition from S=2 to S=1.We reproduce these transformations in our calculations and give a clear physical interpretation.

Structures,stabilities,and electronic properties of GaAs tubelike clusters and single-walled GaAs nanotubes

The geometric structures, stabilities, and electronic properties of （GaAs）n tubelike clusters at up to n = 120 and single-walled GaAs nanotubes （GaAsNTs） were studied by density functional theory （DFT） calculations. A family of stable tubelike structures with a Ga-As alternating arrangement were observed when n ≥ 8 and their structural units （four-membered rings and six-membered rings） obey the general developing formula. The average binding energies of the clusters show that the tubelike cluster with eight atoms in the cross section is the most stable cluster. The size- dependent properties of the frontier molecular orbital surfaces explain why the long and stable tubelike clusters can be obtained successfully. They also illustrate the reason why GaAsNTs can be synthesized experimentally. We also found that the single-walled GaAsNTs can be prepared by the proper assembly of tubelike clusters to form semiconductors with large band gaps.

Electronic, optical properties, surface energies and work functions of Ag_8SnS_6: First-principles method

Ternary metal chalcogenide semiconductor Ag8 Sn S6, which is an efficient photocatalyst under visible light radiation,is studied by plane-wave pseudopotential density functional theory. After geometry optimization, the electronic and optical properties are studied. A scissor operator value of 0.81 e V is introduced to overcome the underestimation of the calculation band gaps. The contribution of different bands is analyzed by virtue of total and partial density of states. Furthermore, in order to understand the optical properties of Ag8 Sn S6, the dielectric function, absorption coefficient, and refractive index are also performed in the energy range from 0 to 11 e V. The absorption spectrum indicates that Ag8 Sn S6has a good absorbency in visible light area. Surface energies and work functions of（411）,（4 13）,（21 1）, and（112） orientations have been calculated. These results reveal the reason for an outstanding photocatalytic activity of Ag8 Sn S6.

Electronic and optical properties of 3N-doped graphdiyne/MoS_(2) heterostructures tuned by biaxial strain and external electric field

The construction of van der Waals(vdW)heterostructures by stacking different two-dimensional layered materials have been recognised as an effective strategy to obtain the desired properties.The 3N-doped graphdiyne(N-GY)has been successfully synthesized in the laboratory.It could be assembled into a supercapacitor and can be used for tensile energy storage.However,the flat band and wide forbidden bands could hinder its application of N-GY layer in optoelectronic and nanoelectronic devices.In order to extend the application of N-GY layer in electronic devices,MoS_(2) was selected to construct an N-GY/MoS_(2) heterostructure due to its good electronic and optical properties.The N-GY/MoS_(2) heterostructure has an optical absorption range from the visible to ultraviolet with a absorption coefficient of 10^(5) cm^(-1).The N-GY/MoS_(2) heterostructure exhibits a type-II band alignment allows the electron–hole to be located on N-GY and MoS_(2) respectively,which can further reduce the electron–hole complexation to increase exciton lifetime.The power conversion efficiency of N-GY/MoS_(2) heterostructure is up to 17.77%,indicating it is a promising candidate material for solar cells.In addition,the external electric field and biaxial strain could effectively tune the electronic structure.Our results provide a theoretical support for the design and application of N-GY/MoS_(2) vdW heterostructures in semiconductor sensors and photovoltaic devices.

Electronic structures and magnetisms of the Co_2TiSb_(1-x)Sn_x(x= 0, 0.25, 0.5) Heusler alloys: A theoretical study of the shape-memory behavior

The total energy, electronic structures, and magnetisms of the Al Cu2Mn-type Co2TiSb1-xSnx（x = 0, 0.25, 0.5） with the different lattice parameter ratios of c/a are studied by using the first-principles calculations. It is found that the phase transformation from the cubic to the tetragonal structure lowers the total energy, indicating that the martensitic phase is more stable and that a phase transition from austenite to martensite may happen at a lower temperature. Thus, a ferromagnetic shape memory effect can be expected to occur in these alloys. The Al Cu2Mn-type Co2TiSb1-xSnx（x = 0, 0.25, 0.5） alloys are weak ferrimagnets in the austenitic phase and martensitic phase.

Electronic structures and edge effects of Ga_2S_2 nanoribbons

Ab initio density functional theory calculations are carried out to predict the electronic properties and relative stability of gallium sulfide nanoribbons(Ga2S2-NRs) with either zigzag- or armchair-terminated edges. It is found that the electronic properties of the nanoribbons are very sensitive to the edge structure. The zigzag nanoribbons(Ga2S2-ZNRs)are ferromagnetic(FM) metallic with spin-polarized edge states regardless of the H-passivation, whereas the bare armchair ones(Ga2S2-ANRs) are semiconducting with an indirect band gap. This band gap exhibits an oscillation behavior as the width increases and finally converges to a constant value. Similar behavior is also found in H-saturated Ga2S2-ANRs,although the band gap converges to a larger value. The relative stabilities of the bare ANRs and ZNRs are investigated by calculating their binding energies. It is found that for a similar width the ANRs are more stable than the ZNRs, and both are more stable than some Ga2S2nanoclusters with stable configurations.

Electronic structure and optical properties of rutile RuO_2 from first principles

The systematic trends of electrionic structure and optical properties of rutile （P42/mnm） RuO2 have been cal- culated by using the plane-wave norm-conserving pseudopotential density functional theory （DFT） method within the generalised gradient approximation （GGA） for the exchange-correlation potential. The obtained equilibrium structure parameters are in excellent agreement with the experimental data. The calculated bulk modulus and elastic constants are also in good agreement with the experimental data and available theoretical calculations. Analysis based on elec- tronic structure and pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonds. Based on a Kramers Kronig analysis of the reflectivity, we have obtained the spectral dependence of the real and imaginary parts of the complex dielectric constant （~1 and z2, respectively） and the refractive index （n）; and comparisons have shown that the theoretical results agree well with the experimental data as well. Meanwhile, we have also calculated the absorption coefficient, reflectivity index, electron energy loss function of RuO2 for radiation up to 30 eV. As a result, the predicted reflectivity index is in good agreement with the experimental data at low energies.

Electronic,thermodynamic and elastic properties of pyrite RuO_2

This paper calculates the elastic, thermodynamic and electronic properties of pyrite （Pa^-3） RuO2 by the plane-wave pseudopotential density functional theory （DFT） method. The lattice parameters, normalized elastic constants, Cauchy pressure, brittle-ductile relations, heat capacity and Debye temperature are successfully obtained. The Murnaghan equation of state shows that pyrite RuO2 is a potential superhard material. Internal coordinate parameter increases with pressure, which disagrees with experimental data. An analysis based on electronic structure and the pseudogap reveals that the bonding nature in RuO2 is a combination of covalent, ionic and metallic bonding. A study of the elastic properties indicates that the pyrite phase is isotropic under usual conditions. The relationship between brittleness and ductility shows that pyrite RuO2 behaves in a ductile matter at zero pressure and the degree of ductility increases with pressure.