Molybdenum disulfide(MoS_(2))has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two-dimensional(2D)structure,which could be developed into numerous high-...Molybdenum disulfide(MoS_(2))has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two-dimensional(2D)structure,which could be developed into numerous high-performance catalysts.The synthesis of ultra-small MoS2 particles(<10 nm)is highly desired in various experimental studies.The ultra-small structure could often lead to a distinct S-Mo coordination state and nonstoichiometric composition in MoSx,minimizing in-plane active sites of the 2D structure and making it probable to regulate the atomic and electronic structure of its intrinsic active sites on a large extent,especially in MoSx clusters.This article summarizes the recent progress of catalysis over ultra-small undoped MoS_(2) particles for renewable fuel production.Through a systematic review of their synthesis,structural,and spectral characteristics,as well as the relationship between their catalytic performance and inherent defects,we aim to provide insights into catalysis over this matrix that may potentially enable advancement in the development of high-performance MoS_(2)-based catalysts for sustainable energy generation in the future.展开更多
The d-band states of catalytic materials participate in adsorbing reactive intermediate species and determine the catalytic behaviors in CO_(2)reduction reactions.However,surface d-band states relating to the photocat...The d-band states of catalytic materials participate in adsorbing reactive intermediate species and determine the catalytic behaviors in CO_(2)reduction reactions.However,surface d-band states relating to the photocatalytic CO_(2)reduction reactions behaviors are rarely concerned.Herein,a slightly amount of Cd^(2+)is decorated on the surface of(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)material(Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4))to tune the surface d-band states for improved CO_(2)+2reduction reactions.The Cd/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)is fabricated via the facile ions-exchange method to make that slightly Zn2+is substituted by Cd^(2+).The Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)exhibits much enhanced photocatalytic activity in CO_(2)reduction reactions to produce CO and water splitting to produce H_(2).Physical characterizations show that the energy band structure is not changed obviously.Density functional theory reveals that Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)possesses a closer shift of d-band center to Fermi level than(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4),suggesting easier adsorption of CO_(2)reduction reactive intermediates after Cd^(2+)decoration.Further calculations confirm that a relatively reduced adsorption Gibbs energy of reactive intermediates in CO_(2)reduction reaction is required on Zn atoms in Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)material,benefiting the photocatalytic CO_(2)reduction reactions.This work engineers surface d-band states by surface Cd^(2+)decoration,which gives an effective strategy to design highly efficient photocatalysts for syngas production.展开更多
Reservoir computing has been considered as a promising intelligent computing paradigm for effectively processing complex temporal information.Exploiting tunable and reproducible dynamics in the single electronic devic...Reservoir computing has been considered as a promising intelligent computing paradigm for effectively processing complex temporal information.Exploiting tunable and reproducible dynamics in the single electronic device have been desired to implement the “reservoir” and the “readout” layer of reservoir computing system.Two-dimensional moiré materials,with an artificial lattice constant many times larger than the atomic length scale,are one type of most studied artificial quantum materials in community of material science and condensed-matter physics over the past years.These materials are featured with gate-tunable periodic potential and electronic correlation,thus varying the electric field allows the electrons in the moiré potential per unit cell to exhibit distinct and reproducible dynamics,showing great promise in robust reservoir computing.Here,we report that a moiré synaptic transistor can be used to implement the reservoir computing system with a homogeneous reservoir-readout architecture.The synaptic transistor is fabricated based on an h-BN/bilayer graphene/h-BN moiré heterostructure,exhibiting ferroelectricity-like hysteretic gate voltage dependence of resistance.Varying the magnitude of the gate voltage enables the moiré transistor to switch between long-term memory and shortterm memory with nonlinear dynamics.By employing the short-and long-term memories as the reservoir nodes and weights of the readout layer,respectively,we construct a full-moiré physical neural network and demonstrate that the classification accuracy of 90.8% can be achieved for the MNIST(Modified National Institute of Standards and Technology) handwritten digits database.Our work would pave the way towards the development of neuromorphic computing based on moiré materials.展开更多
Electrocatalytic conversion of carbon dioxide to high value-added chemicals is a promising method for solving the energy crisis and global warming.Electrochemical active metal-containing conjugated polymers have been ...Electrocatalytic conversion of carbon dioxide to high value-added chemicals is a promising method for solving the energy crisis and global warming.Electrochemical active metal-containing conjugated polymers have been widely studied for heterogeneous carbon dioxide reduction.In the present contribution,we designed and synthesized a stable cobalt phthalocyanine-based conjugated polymer,named CoPPc-TFPPy-CP,and also explored its electro-catalytic application in carbon dioxide reduction to liquid products in an aqueous solution.In the catalyst,cobalt phthalocyanine acts as building blocks connected with 1,3,6,8-tetrakis(4-formyl phenyl)pyrenes via imine-linkages,leading to mesoporous formation polymers with the pore size centered at 4.1nm.And the central co-balt atoms shifted to a higher oxidation state after condensation.With these chemical and structural natures,the catalyst displayed a remarkable electrocatalytic CO_(2) reduction performance with an ethanol Faradaic efficiency of 43.25%at-1.0V vs RHE.While at the same time,the electrochemical reduction process catalyzed by cobalt phthalocyanine produced only carbon monoxide and hydrogen.To the best of our knowledge,CoPPc-TFPPy-CP is the first example among organic polymers and metal-organic frameworks that produces ethanol from CO_(2) with a remarkable selectivity.展开更多
The variations of magnetization and magneto- striction with temperature and stress were investigated through the analysis of the effective field, induced by temperature and stress. A nonlinear magnetostrictive model o...The variations of magnetization and magneto- striction with temperature and stress were investigated through the analysis of the effective field, induced by temperature and stress. A nonlinear magnetostrictive model of giant magnetostrictive materials was proposed. The proposed model can be used to calculate the magnetostrictive characterization of giant magnetostrictive materi- als in different temperatures and under different stresses. The coupling effects of axial stress, magnetic field, and temperature on the magnetostriction of a Terfenol-D rod were numerically simulated as well as experimentally tested. Comparison between the calculating and experimental results shows that the proposed model can better describe the magneto-thermo-mechanical characteristics of Terfenol-D rod under different temperatures and compressive stress. Therefore, the proposed model possesses an important significance for the design of magnetostrictive devices.展开更多
The lattice-oxygen-mediated mechanism is considered as a reasonable mechanism for the electrochemical catalytic oxygen evolution reaction(OER)of NiFe layered double hydroxides(LDHs).A NiFe LDH with distinct lattice co...The lattice-oxygen-mediated mechanism is considered as a reasonable mechanism for the electrochemical catalytic oxygen evolution reaction(OER)of NiFe layered double hydroxides(LDHs).A NiFe LDH with distinct lattice contraction and microcrystallization was synthesized via a simple one-step method using sodium gluconate.The lattice contraction is attributed to the interaction of carbon in sodium gluconate and iron in NiFe LDH.The NiFe LDH with optimized microcrystallization and lattice contraction shows a low overpotential of 217 mV at a current density of 10 mA cm^(−2) and excellent durability of 20 h at a high current density of 100 mA cm^(−2).The results revealed that a contractive metal–oxygen bond could boost the intrinsic activity of active sites and the microcrystallization promotes an increase in the number of active sites in terms of unit area.The chemical environment of oxygen elemental characterization and resistance at different chronopotentiometry times confirm that the lattice oxygen element is indeed involved in the process of OER,supporting the lattice-oxygen-mediated mechanism of NiFe LDH.Density functional theory calculations reveal that contractive metal–oxygen bonds induced a reduction of the adsorption energy barrier of intermediate products,thus improving the intrinsic catalytic activity.The special characteristics of microcrystallization and lattice contraction of NiFe LDH provide a strategy to improve both the number and the intrinsic activity of active sites in a versatile manner.展开更多
The quantitative analysis of zinc isopropyl-isooctyl-dithiophosphate (T204) mixed with lube base oil from Korea with viscosity index 70 (T204-Korea70) is presented by using terahertz time-domain spectroscopy (THz-TDS)...The quantitative analysis of zinc isopropyl-isooctyl-dithiophosphate (T204) mixed with lube base oil from Korea with viscosity index 70 (T204-Korea70) is presented by using terahertz time-domain spectroscopy (THz-TDS).Compared with the middle-infrared spectra of zinc n-butyl-isooctyl-dithiophosphate (T202) and T204,THz spectra of T202 and T204 show the weak broad absorption bands.Then,the absorption coefficients of the T204-Korea70 system follow Beer's law at the concentration from 0.124 to 4.024%.The experimental absorption spectra of T204-Korea70 agree with the calculated ones based on the standard absorption coefficients of T204 and Korea70.The quantitative analysis enables a strategy to monitor the formulation of lubricating oil in real time.展开更多
An Ni-AI-Co system embedded-atom-method potential is constructed for the γ(Ni)/γ'(Ni3A1) superalloy based on experiments and first-principles calculations. The stacking fault energies (SFEs) of the Ni(Co, A1...An Ni-AI-Co system embedded-atom-method potential is constructed for the γ(Ni)/γ'(Ni3A1) superalloy based on experiments and first-principles calculations. The stacking fault energies (SFEs) of the Ni(Co, A1) random solid solutions are calculated as a function of the concentrations of Co and A1. The calculated SFEs decrease with increasing concentrations of Co and A1, which is consistent with the experimental results. The embedding energy term in the present potential has an important influence on the SFEs of the random solid solutions. The cross-slip processes of a screw dislocation in homogenous Ni(Co) solid solutions are simulated using the present potential and the nudged elastic band method. The cross-slip activation energies increase with increasing Co concentration, which implies that the creep resistance of γ(Ni) may be improved by the addition of Co.展开更多
Strategy of anchoring alloy nanoparticles made up of the efficient catalytic element(e.g.,Ni,Fe)on dodecyl sulfate(DS^(-))-intercalated NiFe layered double hydroxides(DS^(-)-NiFe LDH)obtained by a convenient one-step ...Strategy of anchoring alloy nanoparticles made up of the efficient catalytic element(e.g.,Ni,Fe)on dodecyl sulfate(DS^(-))-intercalated NiFe layered double hydroxides(DS^(-)-NiFe LDH)obtained by a convenient one-step hydrothermal coprecipitation method for essentially enhancing oxygen evolution reaction(OER)performance was proposed.The results of structural characterization indicate Pt_(2)FeNi alloy nanoparticles evenly distribute on the surface of DS^(-)-NiFe LDH.The sizes of the Pt_(2)FeNi nanoparticles,closely related to their OER performance,could be wellcontrolled by adjusting the amount of H;PtCl;addition.The composite structure of as-prepared product was stable during processes of synthesis,exfoliation,self-assembly,and subsequent electrocatalytic OER.Rigorous electrochemical test proving the contributing catalytic active sites was located at the interface between Pt_(2)FeNi and DS^(-)-NiFe LDH,and the Ni and Fe were the major active elements while O atoms are adsorption sites.The formation of Pt_(2)FeNi nanoparticles could greatly prompt the reduction of Tafel slope.The best-performing Pt_(2)FeNi/DS^(-)-NiFe LDH with a Pt content of 0.98 wt%achieved low overpotential of 204 mV at 10 mA cm^(-2)and 262 mV at 50 mA cm^(-2).This work provides a convenient and effective strategy to create additional active sites for enhancing OER performance of NiFe LDH and make contribution to its wide application.展开更多
Photocatalytic conversion of CO_(2)into solar fuels provides a bright route for the green and sustainable development of human society.However,the realization of efficient photocatalytic CO_(2)reduction reaction(CO_(2...Photocatalytic conversion of CO_(2)into solar fuels provides a bright route for the green and sustainable development of human society.However,the realization of efficient photocatalytic CO_(2)reduction reaction(CO_(2)RR)is still challenging owing to the sluggish kinetics or unfavorable thermodynamics for basic chemical processes of CO_(2)RR,such as adsorption,activation,conversion and product desorption.To overcome these shortcomings,recent works have demonstrated that surface engineering of semiconductors,such as introducing surface vacancy,surface doping,and cocatalyst loading,serves as effective or promising strategies for improved photocatalytic CO_(2)RR with high activity and selectivity.The essential reason lies in the activation and reaction pathways can be optimized and regulated through the reconstruction of surface atomic and electronic structures.Herein,in this review,we focus on recent research advances about rational design of semiconductor surface for photocatalytic CO_(2)RR.The surface engineering strategies for improved CO_(2)adsorption,activation,and product selectivity will be reviewed.In addition,theoretical calculations along with in situ characterization techniques will be in the spotlight to clarify the kinetics and thermodynamics of the reaction process.The aim of this review is to provide deep understanding and rational guidance on the design of semiconductors for photocatalytic CO_(2)RR.展开更多
To effectively alleviate the ever-increasing energy crisis and environmental issues,clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent demand.Silicon(S...To effectively alleviate the ever-increasing energy crisis and environmental issues,clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent demand.Silicon(Si) with the second most elemental abundance on the crust in the form of silicate or silica(SiO_(2)) minerals,is an advanced emerging material showing high performance in energy-related fields(e.g.batteries,photocatalytic hydrogen evolution).For the improved performance in industry-scale applications,Si materials with delicate nanostructures and ideal compositions in a massive production are highly cherished.On account of the reserve,low cost and diverse micro-nanostructures,silicate minerals are proposed as promising raw materials.In the article,crystal structures and the reduction approaches for silicate minerals,as well as recent progress on the as-reduced Si products for clean energy storage/conversion,are presented systematically.Moreover,some cutting-edge fields involving Si materials are discussed,which may offer deep insights into the rational design of advanced Si nanostructures for extended energy-related fields.展开更多
The sensing of a flame can be performed by using wide-bandgap semiconductors, which offer a high signal-to-noise ratio since they only response the ultraviolet emission in the flame. Diamond is a robust semiconductor ...The sensing of a flame can be performed by using wide-bandgap semiconductors, which offer a high signal-to-noise ratio since they only response the ultraviolet emission in the flame. Diamond is a robust semiconductor with a wide-bandgap of 5.5 e V, exhibiting an intrinsic solar-blindness for deep-ultraviolet(DUV) detection. In this work, by using a submicron thick boron-doped diamond epilayer grown on a type-Ib diamond substrate, a Schottky photodiode device structure- based flame sensor is demonstrated. The photodiode exhibits extremely low dark current in both forward and reverse modes due to the holes depletion in the epilayer. The photodiode has a photoconductivity gain larger than 100 and a threshold wavelength of 330 nm in the forward bias mode. CO and OH emission bands with wavelengths shorter than 330 nm in a flame light are detected at a forward voltage of-10 V. An alcohol lamp flame in the distance of 250 mm is directly detected without a focusing lens of flame light.展开更多
The layered materials have demonstrated great prospects as cost-effective substitutes for precious electrocatalysts in hydrogen evolution reaction.Research efforts have been devoted to synthesizing highly conductive M...The layered materials have demonstrated great prospects as cost-effective substitutes for precious electrocatalysts in hydrogen evolution reaction.Research efforts have been devoted to synthesizing highly conductive MoS_(2) with the substantial cardinal plane and edge active sites.Here,we successfully synthesized a hierarchical 1T/2H–MoS_(2) with sodium ion insertion via a facile hydrothermal method.The contents of the 1T-phase can be flexibly controlled by different hydrothermal temperatures(160 ~ 200°C).And the modified uniformly dispersed 1T/2H–MoS_(2) nanospheres with different d spacings were designed to enhance the electrocatalytic efficiency by adding SiO_(2) and through the ion exchange process of Na OH and HF solution.The as-synthesized Na+intercalated 1T-MoS_(2) nanosphere with an expanded interlayer of 0.95 nm obtained at 160°C exhibits a prominent electrocatalytic performance of hydrogen evolution reaction with a comparable overpotential of 255 m V and a remarkably small Tafel slope of 44 m V/decade.Therefore,this study provides a facile and controllable strategy to yield interlayerexpanded 1T-MoS_(2) nanospheres,making it a potentially competitive hydrogen evolution catalyst for the hydrogen cell.展开更多
We study theoretically the electronic and transport property for an armchair-edge graphene nanoribbon (GNR.) with 12 and 11 transversal atomic lines, respectively. The ONR. is irradiated under an external longitudin...We study theoretically the electronic and transport property for an armchair-edge graphene nanoribbon (GNR.) with 12 and 11 transversal atomic lines, respectively. The ONR. is irradiated under an external longitudinal polarized high-frequency electromagnetic field at low temperatures. Within the framework of linear response theory in the perturbative regime, we examine the joint density of states and the real conductance of the system. It is demonstrated that, by numerical examples, some new photon-assisted intersubband transitions over a certain range of field frequency exist with different selection rules from those of both zigzag-edge GNR. and single-walled carbon nanotube. This opto-electron property dependence of armchair-edge GNR. on field frequency may be used to detect the high-frequency electromagnetic irradiation.展开更多
This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for non...This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for nonequilibrium Green functions, it examines the time-averaged density of states and conductance for the system with photon polarization parallel with and perpendicular to the tunnelling current direction respectively. It is demonstrated that, by analysing some numerical examples, more photon sidebands resonance states and multi-and single-photon transitions are found when diagonal matrix elements dominate the interaction, while the electronic transitions due to multiphoton absorption are more or less suppressed when off-diagonal interaction dominates.展开更多
A new class of 1D quasiperiodic lattices,for which the substitution rules are B→BA,and A→BAB,has been studied in several aspects.The high-dimensional projection method for obtaining the quasilattice is presented.A m...A new class of 1D quasiperiodic lattices,for which the substitution rules are B→BA,and A→BAB,has been studied in several aspects.The high-dimensional projection method for obtaining the quasilattice is presented.A multifractral spectral behavior and gap fabeling properties have been found,which display the perfect quasiperiodicity of the studied model.展开更多
Aprotic lithium–oxygen batteries(LOBs)have been recognized as novel energy storage devices for their outstanding specific energy density,while the large discharge/charge overpotential is a tough barrier to be overcom...Aprotic lithium–oxygen batteries(LOBs)have been recognized as novel energy storage devices for their outstanding specific energy density,while the large discharge/charge overpotential is a tough barrier to be overcome.Here,hetero-structured MoS_(2)/ZnIn_(2)S_(4) nanosheets have been prepared to capture visible light and the generated charge carriers are utilized for promoting both the oxygen reduction reaction and the oxygen evolution reaction.With the light illumination in the discharge process,the abundant photo-inspired electrons serve as the reaction sites to promote the reduction of O_(2) into LiO_(2) which is finally deposited as Li_(2)O_(2).On the contrary,the generated holes in the valence band can contribute to the low oxidization potential of Li_(2)O_(2) during the charge process.It delivers a low charge potential of 3.29 V,with an excellent resulting energy efficiency of 96.7%,much superior to that of 69.2%in the dark condition.It is noted that the involvement of photoelectrons has influenced the growth of Li_(2)O_(2) films on the MoS_(2)/ZnIn_(2)S_(4) nanosheets through the surface-adsorption pathway.The insights from the theoretical calculation confirm that the photoelectrons favor the absorption of LiO_(2) and the formation of the Li_(2)O_(2) film through the surface route.Therefore,this paper provides a deeper understanding of the mechanism of photoinspired charge carriers in LOBs and will enable further exploration of photo-involved energy storage systems.展开更多
By using the Hardy-Wright-Mobius inverse formula,we have improved the Carlsson-Gelatt-Ehrenreich scheme for the inverse problem of cohesive energy.The advantage of the new method is that the inverse formula are in a s...By using the Hardy-Wright-Mobius inverse formula,we have improved the Carlsson-Gelatt-Ehrenreich scheme for the inverse problem of cohesive energy.The advantage of the new method is that the inverse formula are in a sense independent of the geometries of lattices.展开更多
基金support from the Tangshan Talent Funding Project(A202202007)the National Natural Science Foundation of China(21703065)+1 种基金the Natural Science Foundation of Hebei Province(B2018209267,E2022209039)the Basic Science Center Program for Ordered Energy Conversion of the National Natural Science Foundation of China(51888103).
文摘Molybdenum disulfide(MoS_(2))has garnered significant attention in the field of catalysis due to the high density of active sites in its unique two-dimensional(2D)structure,which could be developed into numerous high-performance catalysts.The synthesis of ultra-small MoS2 particles(<10 nm)is highly desired in various experimental studies.The ultra-small structure could often lead to a distinct S-Mo coordination state and nonstoichiometric composition in MoSx,minimizing in-plane active sites of the 2D structure and making it probable to regulate the atomic and electronic structure of its intrinsic active sites on a large extent,especially in MoSx clusters.This article summarizes the recent progress of catalysis over ultra-small undoped MoS_(2) particles for renewable fuel production.Through a systematic review of their synthesis,structural,and spectral characteristics,as well as the relationship between their catalytic performance and inherent defects,we aim to provide insights into catalysis over this matrix that may potentially enable advancement in the development of high-performance MoS_(2)-based catalysts for sustainable energy generation in the future.
基金the financial support from the National Natural Science Foundation of China(22072183)the Natural Science Foundation of Hunan Province,China(2022JJ30690)supported in part by the High Performance Computing Center of Central South University。
文摘The d-band states of catalytic materials participate in adsorbing reactive intermediate species and determine the catalytic behaviors in CO_(2)reduction reactions.However,surface d-band states relating to the photocatalytic CO_(2)reduction reactions behaviors are rarely concerned.Herein,a slightly amount of Cd^(2+)is decorated on the surface of(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)material(Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4))to tune the surface d-band states for improved CO_(2)+2reduction reactions.The Cd/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)is fabricated via the facile ions-exchange method to make that slightly Zn2+is substituted by Cd^(2+).The Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)exhibits much enhanced photocatalytic activity in CO_(2)reduction reactions to produce CO and water splitting to produce H_(2).Physical characterizations show that the energy band structure is not changed obviously.Density functional theory reveals that Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)possesses a closer shift of d-band center to Fermi level than(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4),suggesting easier adsorption of CO_(2)reduction reactive intermediates after Cd^(2+)decoration.Further calculations confirm that a relatively reduced adsorption Gibbs energy of reactive intermediates in CO_(2)reduction reaction is required on Zn atoms in Cd^(2+)/(CuGa)_(x)Zn_(1-2x)Ga_(2)S_(4)material,benefiting the photocatalytic CO_(2)reduction reactions.This work engineers surface d-band states by surface Cd^(2+)decoration,which gives an effective strategy to design highly efficient photocatalysts for syngas production.
基金supported in part by the National Natural Science Foundation of China(Grant Nos.62122036,12322407,62034004,61921005,12074176,and 61974176)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB44000000)+1 种基金the Fundamental Research Funds for the Central Universities(Grant Nos.020414380203 and 020414380179)the support from the AIQ foundation。
文摘Reservoir computing has been considered as a promising intelligent computing paradigm for effectively processing complex temporal information.Exploiting tunable and reproducible dynamics in the single electronic device have been desired to implement the “reservoir” and the “readout” layer of reservoir computing system.Two-dimensional moiré materials,with an artificial lattice constant many times larger than the atomic length scale,are one type of most studied artificial quantum materials in community of material science and condensed-matter physics over the past years.These materials are featured with gate-tunable periodic potential and electronic correlation,thus varying the electric field allows the electrons in the moiré potential per unit cell to exhibit distinct and reproducible dynamics,showing great promise in robust reservoir computing.Here,we report that a moiré synaptic transistor can be used to implement the reservoir computing system with a homogeneous reservoir-readout architecture.The synaptic transistor is fabricated based on an h-BN/bilayer graphene/h-BN moiré heterostructure,exhibiting ferroelectricity-like hysteretic gate voltage dependence of resistance.Varying the magnitude of the gate voltage enables the moiré transistor to switch between long-term memory and shortterm memory with nonlinear dynamics.By employing the short-and long-term memories as the reservoir nodes and weights of the readout layer,respectively,we construct a full-moiré physical neural network and demonstrate that the classification accuracy of 90.8% can be achieved for the MNIST(Modified National Institute of Standards and Technology) handwritten digits database.Our work would pave the way towards the development of neuromorphic computing based on moiré materials.
基金the financial support from the National Natural Science Foundation of China(22005099)。
文摘Electrocatalytic conversion of carbon dioxide to high value-added chemicals is a promising method for solving the energy crisis and global warming.Electrochemical active metal-containing conjugated polymers have been widely studied for heterogeneous carbon dioxide reduction.In the present contribution,we designed and synthesized a stable cobalt phthalocyanine-based conjugated polymer,named CoPPc-TFPPy-CP,and also explored its electro-catalytic application in carbon dioxide reduction to liquid products in an aqueous solution.In the catalyst,cobalt phthalocyanine acts as building blocks connected with 1,3,6,8-tetrakis(4-formyl phenyl)pyrenes via imine-linkages,leading to mesoporous formation polymers with the pore size centered at 4.1nm.And the central co-balt atoms shifted to a higher oxidation state after condensation.With these chemical and structural natures,the catalyst displayed a remarkable electrocatalytic CO_(2) reduction performance with an ethanol Faradaic efficiency of 43.25%at-1.0V vs RHE.While at the same time,the electrochemical reduction process catalyzed by cobalt phthalocyanine produced only carbon monoxide and hydrogen.To the best of our knowledge,CoPPc-TFPPy-CP is the first example among organic polymers and metal-organic frameworks that produces ethanol from CO_(2) with a remarkable selectivity.
基金supported by the National Natural Science Foundation of China (Nos. 50971056 and 51171057)the Youth Natural Science Foundation of Hebei Province (No. E2011202002)
文摘The variations of magnetization and magneto- striction with temperature and stress were investigated through the analysis of the effective field, induced by temperature and stress. A nonlinear magnetostrictive model of giant magnetostrictive materials was proposed. The proposed model can be used to calculate the magnetostrictive characterization of giant magnetostrictive materi- als in different temperatures and under different stresses. The coupling effects of axial stress, magnetic field, and temperature on the magnetostriction of a Terfenol-D rod were numerically simulated as well as experimentally tested. Comparison between the calculating and experimental results shows that the proposed model can better describe the magneto-thermo-mechanical characteristics of Terfenol-D rod under different temperatures and compressive stress. Therefore, the proposed model possesses an important significance for the design of magnetostrictive devices.
基金National Natural Science Foundation of China,Grant/Award Numbers:51874357,51872333,U20A20123。
文摘The lattice-oxygen-mediated mechanism is considered as a reasonable mechanism for the electrochemical catalytic oxygen evolution reaction(OER)of NiFe layered double hydroxides(LDHs).A NiFe LDH with distinct lattice contraction and microcrystallization was synthesized via a simple one-step method using sodium gluconate.The lattice contraction is attributed to the interaction of carbon in sodium gluconate and iron in NiFe LDH.The NiFe LDH with optimized microcrystallization and lattice contraction shows a low overpotential of 217 mV at a current density of 10 mA cm^(−2) and excellent durability of 20 h at a high current density of 100 mA cm^(−2).The results revealed that a contractive metal–oxygen bond could boost the intrinsic activity of active sites and the microcrystallization promotes an increase in the number of active sites in terms of unit area.The chemical environment of oxygen elemental characterization and resistance at different chronopotentiometry times confirm that the lattice oxygen element is indeed involved in the process of OER,supporting the lattice-oxygen-mediated mechanism of NiFe LDH.Density functional theory calculations reveal that contractive metal–oxygen bonds induced a reduction of the adsorption energy barrier of intermediate products,thus improving the intrinsic catalytic activity.The special characteristics of microcrystallization and lattice contraction of NiFe LDH provide a strategy to improve both the number and the intrinsic activity of active sites in a versatile manner.
基金Supported by the Program for New Century Excellent Talents in University(No NCET-08-0841)the Beijing Natural Science Foundation(No 4122064)the Foresight Fund Program from China University of Petroleum(Beijing)(No QZDX-2010-01).
文摘The quantitative analysis of zinc isopropyl-isooctyl-dithiophosphate (T204) mixed with lube base oil from Korea with viscosity index 70 (T204-Korea70) is presented by using terahertz time-domain spectroscopy (THz-TDS).Compared with the middle-infrared spectra of zinc n-butyl-isooctyl-dithiophosphate (T202) and T204,THz spectra of T202 and T204 show the weak broad absorption bands.Then,the absorption coefficients of the T204-Korea70 system follow Beer's law at the concentration from 0.124 to 4.024%.The experimental absorption spectra of T204-Korea70 agree with the calculated ones based on the standard absorption coefficients of T204 and Korea70.The quantitative analysis enables a strategy to monitor the formulation of lubricating oil in real time.
基金Supported by the National Natural Science Foundation of China under Grant No 10574042, and the Guizhou Provincial Science and Technology Foundation of China under Grant No 20052088.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB606402)the National Natural Science Foundation of China(Grant No.51071091)
文摘An Ni-AI-Co system embedded-atom-method potential is constructed for the γ(Ni)/γ'(Ni3A1) superalloy based on experiments and first-principles calculations. The stacking fault energies (SFEs) of the Ni(Co, A1) random solid solutions are calculated as a function of the concentrations of Co and A1. The calculated SFEs decrease with increasing concentrations of Co and A1, which is consistent with the experimental results. The embedding energy term in the present potential has an important influence on the SFEs of the random solid solutions. The cross-slip processes of a screw dislocation in homogenous Ni(Co) solid solutions are simulated using the present potential and the nudged elastic band method. The cross-slip activation energies increase with increasing Co concentration, which implies that the creep resistance of γ(Ni) may be improved by the addition of Co.
基金the financial support by the National Natural Science Foundation of China(51874357,51872333,U20A20123)Innovative Research Group of Hunan Provincial Natural Science Foundation of China(2019JJ10006)support from Shenghua Scholar Program of Central South University.R.M.acknowledges support from JSPS KAKENNHI(18H03869)。
文摘Strategy of anchoring alloy nanoparticles made up of the efficient catalytic element(e.g.,Ni,Fe)on dodecyl sulfate(DS^(-))-intercalated NiFe layered double hydroxides(DS^(-)-NiFe LDH)obtained by a convenient one-step hydrothermal coprecipitation method for essentially enhancing oxygen evolution reaction(OER)performance was proposed.The results of structural characterization indicate Pt_(2)FeNi alloy nanoparticles evenly distribute on the surface of DS^(-)-NiFe LDH.The sizes of the Pt_(2)FeNi nanoparticles,closely related to their OER performance,could be wellcontrolled by adjusting the amount of H;PtCl;addition.The composite structure of as-prepared product was stable during processes of synthesis,exfoliation,self-assembly,and subsequent electrocatalytic OER.Rigorous electrochemical test proving the contributing catalytic active sites was located at the interface between Pt_(2)FeNi and DS^(-)-NiFe LDH,and the Ni and Fe were the major active elements while O atoms are adsorption sites.The formation of Pt_(2)FeNi nanoparticles could greatly prompt the reduction of Tafel slope.The best-performing Pt_(2)FeNi/DS^(-)-NiFe LDH with a Pt content of 0.98 wt%achieved low overpotential of 204 mV at 10 mA cm^(-2)and 262 mV at 50 mA cm^(-2).This work provides a convenient and effective strategy to create additional active sites for enhancing OER performance of NiFe LDH and make contribution to its wide application.
基金financially supported by JSPS KAKENHI(JP18H02065)Photo-excitonic Project in Hokkaido University,National Natural Science Foundation of China(21633004,22002060,and 51872138)+4 种基金Natural Science Foundation of Jiangsu Province(BK20181380)Qing Lan Project,Six Talent Peaks Project in Jiangsu Province(XCL-029)Priority Academic Program Development of the Jiangsu Higher Education Institutions(PAPD)the support provided by the China Scholarships Council(202008320109)China Postdoctoral Science Foundation(2020M681564)。
文摘Photocatalytic conversion of CO_(2)into solar fuels provides a bright route for the green and sustainable development of human society.However,the realization of efficient photocatalytic CO_(2)reduction reaction(CO_(2)RR)is still challenging owing to the sluggish kinetics or unfavorable thermodynamics for basic chemical processes of CO_(2)RR,such as adsorption,activation,conversion and product desorption.To overcome these shortcomings,recent works have demonstrated that surface engineering of semiconductors,such as introducing surface vacancy,surface doping,and cocatalyst loading,serves as effective or promising strategies for improved photocatalytic CO_(2)RR with high activity and selectivity.The essential reason lies in the activation and reaction pathways can be optimized and regulated through the reconstruction of surface atomic and electronic structures.Herein,in this review,we focus on recent research advances about rational design of semiconductor surface for photocatalytic CO_(2)RR.The surface engineering strategies for improved CO_(2)adsorption,activation,and product selectivity will be reviewed.In addition,theoretical calculations along with in situ characterization techniques will be in the spotlight to clarify the kinetics and thermodynamics of the reaction process.The aim of this review is to provide deep understanding and rational guidance on the design of semiconductors for photocatalytic CO_(2)RR.
基金financially supported by National Natural Science Foundation of China(51702291,51874357,U20A20123)the China Postdoctoral Science Foundation(2020M682352)+1 种基金State Key Laboratory of Powder Metallurgy,Central South University,Changsha,Chinasupport from the Youth Talent Program of Zhengzhou University and Henan Provincial Key Technology R&D Program(212102210597)。
文摘To effectively alleviate the ever-increasing energy crisis and environmental issues,clean and sustainable energy-related materials as well as the corresponding storage/conversion devices are in urgent demand.Silicon(Si) with the second most elemental abundance on the crust in the form of silicate or silica(SiO_(2)) minerals,is an advanced emerging material showing high performance in energy-related fields(e.g.batteries,photocatalytic hydrogen evolution).For the improved performance in industry-scale applications,Si materials with delicate nanostructures and ideal compositions in a massive production are highly cherished.On account of the reserve,low cost and diverse micro-nanostructures,silicate minerals are proposed as promising raw materials.In the article,crystal structures and the reduction approaches for silicate minerals,as well as recent progress on the as-reduced Si products for clean energy storage/conversion,are presented systematically.Moreover,some cutting-edge fields involving Si materials are discussed,which may offer deep insights into the rational design of advanced Si nanostructures for extended energy-related fields.
基金supported by Grant-in-Aid for Scientific Research in the Ministry of Education,Culture,Sports,Science and Technology of the Japanese Government(No.18360341)
文摘The sensing of a flame can be performed by using wide-bandgap semiconductors, which offer a high signal-to-noise ratio since they only response the ultraviolet emission in the flame. Diamond is a robust semiconductor with a wide-bandgap of 5.5 e V, exhibiting an intrinsic solar-blindness for deep-ultraviolet(DUV) detection. In this work, by using a submicron thick boron-doped diamond epilayer grown on a type-Ib diamond substrate, a Schottky photodiode device structure- based flame sensor is demonstrated. The photodiode exhibits extremely low dark current in both forward and reverse modes due to the holes depletion in the epilayer. The photodiode has a photoconductivity gain larger than 100 and a threshold wavelength of 330 nm in the forward bias mode. CO and OH emission bands with wavelengths shorter than 330 nm in a flame light are detected at a forward voltage of-10 V. An alcohol lamp flame in the distance of 250 mm is directly detected without a focusing lens of flame light.
基金supported by National Natural Science Foundation of China(Grant no.51702291)The National Science Foundation for Post-doctoral Scientists of China(Grant no.2016M602261)+2 种基金Foundation of Henan Educational Committee(Grant no.18A150016)State Key Laboratory of Powder Metallurgy,Central South University,Changsha,ChinaDevelopment Fund for Outstanding Young Teachers of Zhengzhou University。
文摘The layered materials have demonstrated great prospects as cost-effective substitutes for precious electrocatalysts in hydrogen evolution reaction.Research efforts have been devoted to synthesizing highly conductive MoS_(2) with the substantial cardinal plane and edge active sites.Here,we successfully synthesized a hierarchical 1T/2H–MoS_(2) with sodium ion insertion via a facile hydrothermal method.The contents of the 1T-phase can be flexibly controlled by different hydrothermal temperatures(160 ~ 200°C).And the modified uniformly dispersed 1T/2H–MoS_(2) nanospheres with different d spacings were designed to enhance the electrocatalytic efficiency by adding SiO_(2) and through the ion exchange process of Na OH and HF solution.The as-synthesized Na+intercalated 1T-MoS_(2) nanosphere with an expanded interlayer of 0.95 nm obtained at 160°C exhibits a prominent electrocatalytic performance of hydrogen evolution reaction with a comparable overpotential of 255 m V and a remarkably small Tafel slope of 44 m V/decade.Therefore,this study provides a facile and controllable strategy to yield interlayerexpanded 1T-MoS_(2) nanospheres,making it a potentially competitive hydrogen evolution catalyst for the hydrogen cell.
基金Supported by the National Natural Science Foundation of China under Grant No 10574042, and the Research Foundation of Hunan Education Commission under Grant No 04A031.
基金Supported by the National Natural Science Foundation of China under Grant No 10574042, the Specialized Research Fund for the Doctoral Prozram of Hizher Education of China under Grant No 20060542002, and the Hunan Provincial Natural Science Foundation of China under Grant No 06JJ2097
文摘We study theoretically the electronic and transport property for an armchair-edge graphene nanoribbon (GNR.) with 12 and 11 transversal atomic lines, respectively. The ONR. is irradiated under an external longitudinal polarized high-frequency electromagnetic field at low temperatures. Within the framework of linear response theory in the perturbative regime, we examine the joint density of states and the real conductance of the system. It is demonstrated that, by numerical examples, some new photon-assisted intersubband transitions over a certain range of field frequency exist with different selection rules from those of both zigzag-edge GNR. and single-walled carbon nanotube. This opto-electron property dependence of armchair-edge GNR. on field frequency may be used to detect the high-frequency electromagnetic irradiation.
基金Project supported by the National Natural Science Foundation of China (Grant No 10574042) and the Guizhou Provincial Science and Technology Foundation of China (Grant No 20052088).
文摘This paper investigates theoretically the electronic structure and transport of a two-level quantum dot irradiated under a strong laser field at low temperatures. Using the method of Keldysh equation of motion for nonequilibrium Green functions, it examines the time-averaged density of states and conductance for the system with photon polarization parallel with and perpendicular to the tunnelling current direction respectively. It is demonstrated that, by analysing some numerical examples, more photon sidebands resonance states and multi-and single-photon transitions are found when diagonal matrix elements dominate the interaction, while the electronic transitions due to multiphoton absorption are more or less suppressed when off-diagonal interaction dominates.
基金Supported by the National Natural Science Foundation of China。
文摘A new class of 1D quasiperiodic lattices,for which the substitution rules are B→BA,and A→BAB,has been studied in several aspects.The high-dimensional projection method for obtaining the quasilattice is presented.A multifractral spectral behavior and gap fabeling properties have been found,which display the perfect quasiperiodicity of the studied model.
基金China Postdoctoral Science Foundation,Grant/Award Number:2019M661825Natural Science Foundation of Jiangsu Province,Grant/Award Numbers:BK20190413,BK20210616Japan Society。
文摘Aprotic lithium–oxygen batteries(LOBs)have been recognized as novel energy storage devices for their outstanding specific energy density,while the large discharge/charge overpotential is a tough barrier to be overcome.Here,hetero-structured MoS_(2)/ZnIn_(2)S_(4) nanosheets have been prepared to capture visible light and the generated charge carriers are utilized for promoting both the oxygen reduction reaction and the oxygen evolution reaction.With the light illumination in the discharge process,the abundant photo-inspired electrons serve as the reaction sites to promote the reduction of O_(2) into LiO_(2) which is finally deposited as Li_(2)O_(2).On the contrary,the generated holes in the valence band can contribute to the low oxidization potential of Li_(2)O_(2) during the charge process.It delivers a low charge potential of 3.29 V,with an excellent resulting energy efficiency of 96.7%,much superior to that of 69.2%in the dark condition.It is noted that the involvement of photoelectrons has influenced the growth of Li_(2)O_(2) films on the MoS_(2)/ZnIn_(2)S_(4) nanosheets through the surface-adsorption pathway.The insights from the theoretical calculation confirm that the photoelectrons favor the absorption of LiO_(2) and the formation of the Li_(2)O_(2) film through the surface route.Therefore,this paper provides a deeper understanding of the mechanism of photoinspired charge carriers in LOBs and will enable further exploration of photo-involved energy storage systems.
基金Supported by the National Natural Science Foundation of China,and in part by the International Program in the Physical Sciences,Uppsala University,Sweden.
文摘By using the Hardy-Wright-Mobius inverse formula,we have improved the Carlsson-Gelatt-Ehrenreich scheme for the inverse problem of cohesive energy.The advantage of the new method is that the inverse formula are in a sense independent of the geometries of lattices.