This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the...This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the strength of the pumping field. An equivalent incoherent pumping rate is introduced in this simplified theoretical model which exploits the dependence of this feature. The experimental observation is presented as evidence of the breaking point where the injected power is about 0.08 mW.展开更多
In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Ke...In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.展开更多
A novel method to control the group velocity of light propagation in a two-level atomic system without additional optical field is proposed. Numerical result and experimental data shows that by changing the magnetic f...A novel method to control the group velocity of light propagation in a two-level atomic system without additional optical field is proposed. Numerical result and experimental data shows that by changing the magnetic field intensity and vapor temperature, the group velocity of probe light can be controlled in an appropriate region.展开更多
The T_(1)(Al_(2) CuLi)phase is one of the most effective strengthening nanoscale-precipitate in Al-Cu alloys with Li.However,its formation and evolution still need to be further clarified during aging due to the compl...The T_(1)(Al_(2) CuLi)phase is one of the most effective strengthening nanoscale-precipitate in Al-Cu alloys with Li.However,its formation and evolution still need to be further clarified during aging due to the complex precipitation sequences.Here,a detailed investigation has been carried out on the atomic struc-tural evolution of T_(1) precipitate in an aged Al-Cu-Li-Mg-Ag alloy using state-of-the-art Cs-corrected high-angle annular dark field(HAADF)-coupled with integrated differential phase contrast(iDPC)-scanning transmission electron microscopy(STEM)and energy-dispersive X-ray spectroscopy(EDXS)techniques.An intermediate T_(1)’phase between T_(1p) and T_(1) phase,with a crystal structure and orientation rela-tionship consistent with T_(1),but exhibiting different atomic occupancy and chemical composition was found.We observed the atomic structural transformation from T_(1p) to T_(1)’phase(fcc→hcp),involving only 1/12<112>Al shear component.DFT calculation results validated our proposed structural models and the precipitation sequence.Besides,the distributions of minor solute elements(Ag,Mg,and Zn)in the pre-cipitates exhibited significant differences.These findings may contribute to a further understanding of the nucleation mechanism of T_(1) precipitate.展开更多
Broadband transparent films play a pivotal role in various applications such as lenses and solar cells,particularly porous structured transparent films exhibit significant potential.This study investigates a porous Si...Broadband transparent films play a pivotal role in various applications such as lenses and solar cells,particularly porous structured transparent films exhibit significant potential.This study investigates a porous SiO_(2) refractive index gradient anti-reflective film prepared by atomic layer deposition(ALD).A porous SiO_(2) film with gradual porosity was obtained by phosphoric acid etching of Al_(2)O_(3)/SiO_(2) multilayers with gradient Al2O3 ratios,achieving a gradual decrease in refractive index from the substrate to the surface.The film exhibited an average transmittance as high as 97.8%within the wavelength range from 320 nm to 1200 nm.The environmental adaptability was further enhanced by surface modification using rare earth oxide(REO)La_(2)O_(3),resulting in formation of a lotus leaf-like structure and achieving a water contact angle of 100.0°.These data proved that the modification significantly improved hydrophobic self-cleaning capability while maintaining exceptional transparency of the film.The surface structure of the modified film remained undamaged even after undergoing wipe testing,demonstrating its excellent surface durability.展开更多
Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Her...Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.展开更多
Single-atom catalysts(SACs),in which isolated metal atoms such as palladium(Pd)are anchored on solid supports,promise breakthroughs in energy conversion and catalysis.However,balancing their activity(reaction speed)an...Single-atom catalysts(SACs),in which isolated metal atoms such as palladium(Pd)are anchored on solid supports,promise breakthroughs in energy conversion and catalysis.However,balancing their activity(reaction speed)and stability(longevity)remains challenging,as the interplay between metal atoms,supports,and reactants is poorly understood.展开更多
Heat dissipation highly relies on the thermal conductivity(κ)of materials.Materials with large bandgaps and signifcant atomic mass ratios,such as BAs,SiC,andθ-TaN,have attracted considerable attention due to their p...Heat dissipation highly relies on the thermal conductivity(κ)of materials.Materials with large bandgaps and signifcant atomic mass ratios,such as BAs,SiC,andθ-TaN,have attracted considerable attention due to their potential for achieving ultra-highκ,with BAs serving as a particularly representative example due to its unique combination of large bandgap and high thermal conductivity.In this paper,the efects of atomic mass modifcation on phonon bandgap andκare systematically investigated using a BAs model,accounting for both three-and four-phonon scattering processes.A 20%increase inκcan be obtained by substituting B,achieved through widening the phonon bandgap,which suppresses phonon scattering.Notably,the AAOO four-phonon scattering channel is more suppressed than the AAO three-phonon channel,leading to an increased phonon lifetime(τ).For As,κcan also be enhanced by 5%when replaced by lighter atoms,such as^(69)As,primarily due to the increased phonon group velocity(υ).We systematically clarify how atomic-mass-induced bandgap variations afectτ,υ,and thereforeκin wide-bandgap systems.Our work provides a specifc scheme for further improving the ultra-highκof materials with large bandgaps,which possesses great guiding signifcance.展开更多
For atoms in external electric fields,the hyperpolarizabilities are the coefficients describing the nonlinear interactions contributing to the induced energies at the fourth power of the applied electric fields.Accura...For atoms in external electric fields,the hyperpolarizabilities are the coefficients describing the nonlinear interactions contributing to the induced energies at the fourth power of the applied electric fields.Accurate evaluations of these coefficients for various systems are crucial for improving precision in advanced atom-based optical lattice clocks and for estimating field-induced effects in atoms for quantum information applications.However,there is a notable scarcity of research on atomic hyperpolarizabilities,especially in the relativistic realm.Our work addresses this gap by establishing a novel set of alternative formulas for the hyperpolarizability based on the fourth-order perturbation theory.These formulas offer a more reasonable regrouping of scalar and tensor components compared to previous formulas,thereby enhancing their correctness and applicability.To validate our formulas,we perform the calculations for the ground and low-lying excited pure states of few-electron atoms H,Li,and Be^(+).The highly accurate results obtained for the H atom could serve as benchmarks for further development of other theoretical methods.展开更多
Photocatalytic oxygen reduction for hydrogen peroxide(H_(2)O_(2))synthesis presents a green and costeffective production method.However,achieving highly selective H_(2)O_(2)synthesis remains challenging,necessitating ...Photocatalytic oxygen reduction for hydrogen peroxide(H_(2)O_(2))synthesis presents a green and costeffective production method.However,achieving highly selective H_(2)O_(2)synthesis remains challenging,necessitating precise control over free radical reaction pathways and minimizing undesirable oxidative by-products.Herein,we report for the visible light-driven simultaneous co-photocatalytic reduction of O2to H_(2)O_(2)and oxidation of biomass using the atomic rubidium-nitride modified carbon nitride(CNRb).The optimized CNRb catalyst demonstrates a record photoreduction rate of 8.01 mM h^(-1)for H_(2)O_(2)generation and photooxidation rate of 3.75 mM h^(-1)for furfuryl alcohol to furoic acid,achieving a remarkable solar-to-chemical conversion(SCC)efficiency of up to 2.27%.Experimental characterizations and DFT calculation disclosed that the introducing atomic Rb–N configurations allows for the high-selective generation of superoxide radicals while suppressing hydroxyl free radical formation.This is because the Rb–N serves as the new alternative site to perceive a stronger connection position for O2adsorption and reinforce the capability to extract protons,thereby triggering a high selective redox product formation.This study holds great potential in precisely regulating reactive radical processes at the atomic level,thereby paving the way for efficient synthesis of H_(2)O_(2)coupled with biomass valorization.展开更多
The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-pli...The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-plication.The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost.However,the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface be-tween the matrix and pores,ultimately leading to decreased figure of merit,ZT.Here,we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_(0.5)Sb_(1.5)Te_(3)for preparing high-performance porous thermoelectric materials.Experimental results indi-cate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering,thereby optimizing carrier/phonon transport behaviors,and effectively increasing the ZT by 23.2%(from 0.99 to 1.22 at 350 K).Besides,our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi_(2)Te_(2.7)Se_(0.3),therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.展开更多
Carbon electrocatalyst materials based on lignocellulosic biomass with multi-components,various dimensions,high carbon content,and hierarchical morphology structures have gained great popularity in electrocatalytic ap...Carbon electrocatalyst materials based on lignocellulosic biomass with multi-components,various dimensions,high carbon content,and hierarchical morphology structures have gained great popularity in electrocatalytic applications recently.Due to the catalytic deficiency of neutral carbon atoms,the usage of single lignocellulosic-based carbon materials in electrocatalysis involving energy storage and conversion presents unsatisfactory applicability.However,atomic-level modulation of lignocellulose-based carbon materials can optimize the electronic structures,charge separation,transfer processes,and so forth,which results in substantially enhanced electrocatalytic performance of carbon-based catalysts.This paper reviews the recent advances in the rational design of lignocellulosic-based carbon materials as electrocatalysts from an atomic-level perspective,such as self/external heteroatom doping and metal modification.Then,through systematic discussion of the design principles and reaction mechanisms of the catalysts,the applications of the prepared lignocellulosic-based catalysts in rechargeable batteries and electrocatalysis are reviewed.Finally,the challenges in improving the catalytic performance of lignocellulosic-based carbon materials as electrocatalysts and the prospects in diverse applications are reviewed.This review contributes to the synthesis strategy of lignocellulose-based carbon electrocatalysts via atomic-level modulation,which in turn promotes the lignocellulose valorization for energy storage and conversion.展开更多
Atomic-scale strain mapping has become increasingly vital for investigating deformation mechanisms and the governing principles of solid materials.This is due to the significant impact of atomic-scale strain on the ph...Atomic-scale strain mapping has become increasingly vital for investigating deformation mechanisms and the governing principles of solid materials.This is due to the significant impact of atomic-scale strain on the physical,chemical,and mechanical properties of nanomaterials that comprise functional devices such as nanoelectronics,communication devices,electromechanical systems,and sensors.The advent of advanced electron microscopes has enabled the acquisition of high-magnification images with atomic resolution,providing an exceptional platform for measuring the atomic-scale strain of solid materials.However,accurate and unified strain mapping methods and standards for evaluating atomic-scale strain distribution remain scarce.Consequently,a unified strain mapping framework is proposed for atomic-scale strain measurement.Utilizing finite deformation analysis and the least-squares mathematical method,two types of atomic-scale strain field mapping methods have been developed,including the phase analysis-based methods(PAD and PAS)and the peak matching-based strain mapping method(PMS)for high-resolution scanning transmission electron microscope images.The prototypical 2D materials,graphene and molybdenum disulfide,serve as the subjects for the strain field mapping research,conducted through both simulation and experimentation.Upon comparing the theoretical strain mapping results of single-layer graphene and molybdenum disulfide with and without defects,it is demonstrated that the proposed strain mapping methods,particularly the PMS method,can accurately describe the large deformation surrounding a significant strain gradient.展开更多
Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve ...Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve the superior electrochemical properties of CIBs,the structure design of electrode materials is essential.Herein,2D NiAl-layered double hydroxide(NiAl-LDH)nanoarrays derived from Al2O3 are in-situ grafted to graphene(G)by atomic layer deposition(ALD)and hydrothermal method.The achieved NiAl-LDH@G hybrids with 2D NiAl-LDH arrays grown perpendicularly on graphene surface,can efficiently prevent the stacking of LDHs and enlarge specific surface area to provide more active sites.The NiAl-LDH@G cathode exhibits a maximum discharge capacity of 223.3 mA h g^(-1)and an excellent reversible capacity of 107 mA h g^(-1)over 500 cycles at 100 mA g^(-1)with a high coulombic efficiency around 96%,whereas pure NiAl-LDH has a discharge capacity of only 48.8 mA h g^(-1)and a coulombic efficiency(CE)of about 78%.More importantly,the NiAl-LDH@G electrode has a stable voltage at 1.9 V and an outstanding discharge capacity of higher than 72 mA h g^(-1)after 120 days.Additionally,XRD,XPS,and EDS have been employed to unveil the electrochemical reaction and Cl-storage mechanism of the NiAlLDH@G cathode in CIBs.This work opens a facile and reasonable way for improving electrochemical performance at anion-type rechargeable batteries in terms of cathode material design and mechanism interpretation.展开更多
Liquefied natural gas storage and transportation as well as space propulsion systems have sparked inter-est in the martensitic transformation and behaviours of 316 L stainless steels(SS)under ultra-cryogenic deformati...Liquefied natural gas storage and transportation as well as space propulsion systems have sparked inter-est in the martensitic transformation and behaviours of 316 L stainless steels(SS)under ultra-cryogenic deformation.In this study,high-resolution transmission electron microscopy(HRTEM)and molecular dy-namics(MD)simulations were used to investigate the atomic arrangements and crystalline defects of deformation-induced γ-austenite→ε-martensite→α'-martensite and γ→α'martensitic transforma-tions in 316 L SS at 15 and 173 K.Theγ→εtransformation involves the glide of Shockley partial dislocations on(111)γplanes without a change in atomic spacing.The formation of anα'inclusion in a singleε-band is achieved by a continuous lattice distortion,accompanied by the formation of a tran-sition zone ofα'and the expansion of the average atomic spacings due to dislocation shuffling.Asα'grows further intoγ,the orientation relationship(OR)of theα'changes by lattice bending.This pro-cess follows the Bogers-Burgers-Olson-Cohen model despite it not occurring on intersecting shear bands.Stacking faults and twins can also serve as nucleation sites forα'at 173 K.We also found that direct transformation of γ→α'occurs by the glide of √6aγ[11(2)]/12 dislocations on every(111)γplane with misfit dislocations.Overall,this study provides,for the first time,insights into the atomic-scale mech-anisms of various two-step and one-step martensitic transformations induced by cryogenic deformation and corresponding local strain,enhancing our understanding of the role of martensitic transformation under ultra-cryogenic-temperature deformation in controlling the properties.展开更多
Efficient water dissociation catalysts are important for reducing the activation energy barrier of water molecules in the field of energy conversio n.Herein,symmetry-bro ken Rh ensemble induced by mandated charge was ...Efficient water dissociation catalysts are important for reducing the activation energy barrier of water molecules in the field of energy conversio n.Herein,symmetry-bro ken Rh ensemble induced by mandated charge was established to boost the catalytic activity toward water dissociation.As an experimental verification,the turnover frequency of 1.0-RTO_(V4)in hydrogen generation from ammonia borane hydrolysis reaches up to 2838 min-1(24828 min^(-1)depend on Rh dispersion),exceeding the benchmark set up by state-of-the-art catalysts.The transfer of mandated charge from O_(V)to Rh near O_(V)breaks the local symmetry of Rh nanoparticle and forms Rh^(γ-)(electron-aggregation Rh)-Rh interfacial atomic ensemble.This symmetry-broken Rh ensemble is the reason for the high activity of the catalyst.This work provides an effective electronic regulation strategy based on symmetry-broken atomic ensemble induced by mandated charge,designed to stimulate the limiting activity of metal catalyst in the field of next generation energy chemistry.展开更多
The exploitation of durable and highly active Pt-based electrocatalysts for the oxygen reduction reaction(ORR)is essential for the commercialization of proton exchange membrane fuel cells(PEMFCs).Herein,we designed Pt...The exploitation of durable and highly active Pt-based electrocatalysts for the oxygen reduction reaction(ORR)is essential for the commercialization of proton exchange membrane fuel cells(PEMFCs).Herein,we designed Pt@Pt_(3)Ti core-shell nanoparticles with atomic-controllable shells through precise thermal diffusing Ti into Pt nanoparticles for effective and durable ORR.Combining theoretical and experiment analysis,we found that the lattice strain of Pt_(3)Ti shells can be tailored by precisely controlling the thick-ness of Pt_(3)Ti shell in atomic-scale on account of the lattice constant difference between Pt and Pt_(3)Ti to optimize adsorption properties of Pt_(3)Ti for ORR intermediates,thus enhancing its performance.The Pt@Pt_(3)Ti catalyst with one-atomic Pt_(3)Ti shell(Pt@1L-Pt_(3)Ti/TiO_(2)-C)demonstrates excellent performance with mass activity of 592 mA mgpt-1 and durability nearly 19.5-fold that of commercial Pt/C with negligible decay(2%)after 30,000 potential cycles(0.6-1.0 V vs.RHE).Notably,at higher potential cycles(1.0 V-1.5 V vs.RHE),Pt@1L-Pt_(3)Ti/TiO_(2)-C also showed far superior durability than Pt/C(9.6%decayed while 54.8% for commercial Pt/C).This excellent stability is derived from the intrinsic stability of Pt_(3)Ti alloy and the confinement effect of TiO_(2)-C.The catalyst's enhancement was further confirmed in PEMFC configuration.展开更多
To eliminate distortion caused by vertical drift and illusory slopes in atomic force microscopy(AFM)imaging,a lifting-wavelet-based iterative thresholding correction method is proposed in this paper.This method achiev...To eliminate distortion caused by vertical drift and illusory slopes in atomic force microscopy(AFM)imaging,a lifting-wavelet-based iterative thresholding correction method is proposed in this paper.This method achieves high-quality AFM imaging via line-by-line corrections for each distorted profile along the fast axis.The key to this line-by-line correction is to accurately simulate the profile distortion of each scanning row.Therefore,a data preprocessing approach is first developed to roughly filter out most of the height data that impairs the accuracy of distortion modeling.This process is implemented through an internal double-screening mechanism.A line-fitting method is adopted to preliminarily screen out the obvious specimens.Lifting wavelet analysis is then carried out to identify the base parts that are mistakenly filtered out as specimens so as to preserve most of the base profiles and provide a good basis for further distortion modeling.Next,an iterative thresholding algorithm is developed to precisely simulate the profile distortion.By utilizing the roughly screened base profile,the optimal threshold,which is used to screen out the pure bases suitable for distortion modeling,is determined through iteration with a specified error rule.On this basis,the profile distortion is accurately modeled through line fitting on the finely screened base data,and the correction is implemented by subtracting the modeling result from the distorted profile.Finally,the effectiveness of the proposed method is verified through experiments and applications.展开更多
Metal nanoclusters with well-defined atomic structures offer significant promise in the field of catalysis due to their sub-nanometer size and tunable organic-inorganic hybrid structural features.Herein,we successfull...Metal nanoclusters with well-defined atomic structures offer significant promise in the field of catalysis due to their sub-nanometer size and tunable organic-inorganic hybrid structural features.Herein,we successfully synthesized an 11-core copper(Ⅰ)-alkynyl nanocluster(Cu11),which is stabilized by alkynyl ligands derived from a photosensitive rhodamine dye molecule.Notably,this Cu11cluster exhibited excellent photocatalytic hydrogen evolution activity(8.13 mmol g-1h-1)even in the absence of a mediator and noble metal co-catalyst.Furthermore,when Cu11clusters were loaded onto the surface of TiO_(2)nanosheets,the resultant Cu11@TiO_(2)nanocomposites exhibited a significant enhancement in hydrogen evolution efficiency,which is 60 times higher than that of pure TiO_(2)nanosheets.The incorporation of Cu11clusters within the Cu11@TiO_(2)effectively inhibits the recombination of photogenerated electrons and holes,thereby accelerating the charge separation and migration in the composite material.This work introduces a novel perspective for designing highly active copper cluster-based photocatalysts.展开更多
Efficient CO_(2)photoreduction to produce fuel remains a great challenge,due to the fast recombination of photogenerated charge carriers and the lack of effective reactive sites in the developed photocatalysts.Herein,...Efficient CO_(2)photoreduction to produce fuel remains a great challenge,due to the fast recombination of photogenerated charge carriers and the lack of effective reactive sites in the developed photocatalysts.Herein,single Co atoms(Co_(SA))were highly dispersed on hydrothermally synthesized BiOCl nanosheets(BOC)by a facile two-step electrostatic self-assembly and pyrolysis method.The obtained Co_(SA)-BOC could be performed for efficient CO_(2)photoreduction to stoichiometrically produce CO and O_(2)at the ratio of 2:1,with the CO evolution rate reaching 45.93 μmol g^(-1)h^(-1),~4 times that of the pristine BOC.This distinctly improved photocatalytic performance for Co_(SA)-BOC should benefit from the introduction of atomically dispersed Co–O_(4)coordination structures,which could accelerate the migration of photogenerated charge carriers to surface by creating an impurity energy level in the forbidden band,and act as the reactive sites to deliver the photogenerated electrons to activate CO_(2)molecules for CO production.This work provides a facile and reliable strategy to highly disperse single atoms on low-dimensional semiconductors for efficient CO_(2)photoreduction to selectively produce CO.展开更多
基金Project supported by the Key Program of the National Natural Science Foundation of China (Grant No.60837004)the Key Project of Jiangxi Electric Power Company (Grant Nos.200950801 and 200950802)
文摘This paper investigates the breaking point between fast- and slow-light in a degenerate two-level atomic system, where fast-light can be converted to slow-light arbitrarily on a single transition line by adjusting the strength of the pumping field. An equivalent incoherent pumping rate is introduced in this simplified theoretical model which exploits the dependence of this feature. The experimental observation is presented as evidence of the breaking point where the injected power is about 0.08 mW.
文摘In this paper, we have proposed the numerical calculations to study the quantum entanglement (QE) of moving two-level atom interacting with a coherent and the thermal field influenced by intrinsic decoherence (ID), Kerr medium (non-linear) and the Stark effect. The wave function of the complete system interacting with a coherent and the thermal field is calculated numerically affected by ID, Kerr (non-linear) and Stark effects. It has been seen that the Stark, Kerr, ID and the thermal environment have a significant effect during the time evolution of the quantum system. Quantum Fisher information (QFI) and QE decrease as the value of the ID parameter is increased in the thermal field without the atomic movement. It is seen that QFI and von Neumann entropy (VNE) show an opposite and periodic response in the presence of atomic motion. The non-linear Kerr medium has a more prominent and significant effect on the QE as the value of the Kerr parameter is decreased. At smaller values of the non-linear Kerr parameter, the VNE increases, however, QFI decreases, so QFI and VNE have a monotonic connection with one another. As the value of the Kerr parameter is increased, the effect of non-linear Kerr doesn’t stay critical on both QFI and QE. However, a periodic response of QE is seen because of the atomic movement which becomes modest under natural impacts. Moreover, it has been seen that QFI and QE rot soon at the smaller values of the Stark parameter. However, as the value of the Stark parameter is increased, the QFI and QE show periodic response even when the atomic movement is absent.
文摘A novel method to control the group velocity of light propagation in a two-level atomic system without additional optical field is proposed. Numerical result and experimental data shows that by changing the magnetic field intensity and vapor temperature, the group velocity of probe light can be controlled in an appropriate region.
基金supported by the Pre-research fund(No.412130024).
文摘The T_(1)(Al_(2) CuLi)phase is one of the most effective strengthening nanoscale-precipitate in Al-Cu alloys with Li.However,its formation and evolution still need to be further clarified during aging due to the complex precipitation sequences.Here,a detailed investigation has been carried out on the atomic struc-tural evolution of T_(1) precipitate in an aged Al-Cu-Li-Mg-Ag alloy using state-of-the-art Cs-corrected high-angle annular dark field(HAADF)-coupled with integrated differential phase contrast(iDPC)-scanning transmission electron microscopy(STEM)and energy-dispersive X-ray spectroscopy(EDXS)techniques.An intermediate T_(1)’phase between T_(1p) and T_(1) phase,with a crystal structure and orientation rela-tionship consistent with T_(1),but exhibiting different atomic occupancy and chemical composition was found.We observed the atomic structural transformation from T_(1p) to T_(1)’phase(fcc→hcp),involving only 1/12<112>Al shear component.DFT calculation results validated our proposed structural models and the precipitation sequence.Besides,the distributions of minor solute elements(Ag,Mg,and Zn)in the pre-cipitates exhibited significant differences.These findings may contribute to a further understanding of the nucleation mechanism of T_(1) precipitate.
文摘Broadband transparent films play a pivotal role in various applications such as lenses and solar cells,particularly porous structured transparent films exhibit significant potential.This study investigates a porous SiO_(2) refractive index gradient anti-reflective film prepared by atomic layer deposition(ALD).A porous SiO_(2) film with gradual porosity was obtained by phosphoric acid etching of Al_(2)O_(3)/SiO_(2) multilayers with gradient Al2O3 ratios,achieving a gradual decrease in refractive index from the substrate to the surface.The film exhibited an average transmittance as high as 97.8%within the wavelength range from 320 nm to 1200 nm.The environmental adaptability was further enhanced by surface modification using rare earth oxide(REO)La_(2)O_(3),resulting in formation of a lotus leaf-like structure and achieving a water contact angle of 100.0°.These data proved that the modification significantly improved hydrophobic self-cleaning capability while maintaining exceptional transparency of the film.The surface structure of the modified film remained undamaged even after undergoing wipe testing,demonstrating its excellent surface durability.
基金supported by National Natural Science Foundation of China(No.523B2070,No.52225606).
文摘Polymeric perylene diimide(PDI)has been evidenced as a good candidate for photocatalytic water oxidation,yet the origin of the photocatalytic oxygen evolution activity remains unclear and needs further exploration.Herein,with crystal and atomic structures of the self-assembled PDI revealed from the X-ray diffraction pattern,the electronic structure is theoretically illustrated by the first-principles density functional theory calculations,suggesting the suitable band structure and the direct electronic transition for efficient photocatalytic oxygen evolution over PDI.It is confirmed that the carbonyl O atoms on the conjugation structure serve as the active sites for oxygen evolution reaction by the crystal orbital Hamiltonian group analysis.The calculations of reaction free energy changes indicate that the oxygen evolution reaction should follow the reaction pathway of H_(2)O→^(*)OH→^(*)O→^(*)OOH→^(*)O_(2)with an overpotential of 0.81 V.Through an in-depth theoretical computational analysis in the atomic and electronic structures,the origin of photocatalytic oxygen evolution activity for PDI is well illustrated,which would help the rational design and modification of polymeric photocatalysts for efficient oxygen evolution.
文摘Single-atom catalysts(SACs),in which isolated metal atoms such as palladium(Pd)are anchored on solid supports,promise breakthroughs in energy conversion and catalysis.However,balancing their activity(reaction speed)and stability(longevity)remains challenging,as the interplay between metal atoms,supports,and reactants is poorly understood.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFA1407001)the Department of Science and Technology of Jiangsu Province(Grant No.BK20220032)+1 种基金support from the Guang Dong Basic and Applied Basic Research Foundation(Grant No.2023A1515010365)support from the Postgraduate Research and Practice Innovation Program of Jiangsu Province under Grant No.KYCX25_1934。
文摘Heat dissipation highly relies on the thermal conductivity(κ)of materials.Materials with large bandgaps and signifcant atomic mass ratios,such as BAs,SiC,andθ-TaN,have attracted considerable attention due to their potential for achieving ultra-highκ,with BAs serving as a particularly representative example due to its unique combination of large bandgap and high thermal conductivity.In this paper,the efects of atomic mass modifcation on phonon bandgap andκare systematically investigated using a BAs model,accounting for both three-and four-phonon scattering processes.A 20%increase inκcan be obtained by substituting B,achieved through widening the phonon bandgap,which suppresses phonon scattering.Notably,the AAOO four-phonon scattering channel is more suppressed than the AAO three-phonon channel,leading to an increased phonon lifetime(τ).For As,κcan also be enhanced by 5%when replaced by lighter atoms,such as^(69)As,primarily due to the increased phonon group velocity(υ).We systematically clarify how atomic-mass-induced bandgap variations afectτ,υ,and thereforeκin wide-bandgap systems.Our work provides a specifc scheme for further improving the ultra-highκof materials with large bandgaps,which possesses great guiding signifcance.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174402 and 12393821)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB0920100 and XDB0920101)+2 种基金the Nature Science Foundation of Hubei Province(Grant Nos.2019CFA058 and 2022CFA013)supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)supported in part by NSF grant PHY-2116679.All the calculations are finished on the APM-Theoretical Computing Cluster(APMTCC)。
文摘For atoms in external electric fields,the hyperpolarizabilities are the coefficients describing the nonlinear interactions contributing to the induced energies at the fourth power of the applied electric fields.Accurate evaluations of these coefficients for various systems are crucial for improving precision in advanced atom-based optical lattice clocks and for estimating field-induced effects in atoms for quantum information applications.However,there is a notable scarcity of research on atomic hyperpolarizabilities,especially in the relativistic realm.Our work addresses this gap by establishing a novel set of alternative formulas for the hyperpolarizability based on the fourth-order perturbation theory.These formulas offer a more reasonable regrouping of scalar and tensor components compared to previous formulas,thereby enhancing their correctness and applicability.To validate our formulas,we perform the calculations for the ground and low-lying excited pure states of few-electron atoms H,Li,and Be^(+).The highly accurate results obtained for the H atom could serve as benchmarks for further development of other theoretical methods.
基金National Natural Science Foundation of China(22309032,22109120,and 62104170)Guangdong Basic and Applied Basic Research Foundation(2022A1515011737)+2 种基金Science and Technology Program of Guangzhou(2023A04J1395)GDAS’Project of Science and Technology Development(2021GDASYL-20210102010)Zhejiang Provincial Natural Science Foundation of China(LY23F040001)。
文摘Photocatalytic oxygen reduction for hydrogen peroxide(H_(2)O_(2))synthesis presents a green and costeffective production method.However,achieving highly selective H_(2)O_(2)synthesis remains challenging,necessitating precise control over free radical reaction pathways and minimizing undesirable oxidative by-products.Herein,we report for the visible light-driven simultaneous co-photocatalytic reduction of O2to H_(2)O_(2)and oxidation of biomass using the atomic rubidium-nitride modified carbon nitride(CNRb).The optimized CNRb catalyst demonstrates a record photoreduction rate of 8.01 mM h^(-1)for H_(2)O_(2)generation and photooxidation rate of 3.75 mM h^(-1)for furfuryl alcohol to furoic acid,achieving a remarkable solar-to-chemical conversion(SCC)efficiency of up to 2.27%.Experimental characterizations and DFT calculation disclosed that the introducing atomic Rb–N configurations allows for the high-selective generation of superoxide radicals while suppressing hydroxyl free radical formation.This is because the Rb–N serves as the new alternative site to perceive a stronger connection position for O2adsorption and reinforce the capability to extract protons,thereby triggering a high selective redox product formation.This study holds great potential in precisely regulating reactive radical processes at the atomic level,thereby paving the way for efficient synthesis of H_(2)O_(2)coupled with biomass valorization.
基金supported by the National Natural Science Foundation of China(Nos.U21A2054,21905007)the Key Discipline of Materials Science and Engineering,Bureau of Education of Guangzhou(Grant No.202255464).
文摘The bismuth-telluride-based alloy is the only thermoelectric material commercialized for the applications of refrigeration and energy harvesting,but its low cost-effectiveness severely restricts its large-scale ap-plication.The introduction of a porous structure in bulk thermoelectric materials has been theoretically proven to effectively reduce thermal conductivity and cost.However,the electrical properties of highly porous materials are considerably suppressed due to the strong carrier scattering at the interface be-tween the matrix and pores,ultimately leading to decreased figure of merit,ZT.Here,we use an atomic layer deposition strategy to introduce some hollow glass bubbles with nano-oxide layers into commercial Bi_(0.5)Sb_(1.5)Te_(3)for preparing high-performance porous thermoelectric materials.Experimental results indi-cate that the nano-oxide layers weaken carrier scattering at the interface between pores and matrix while maintaining high-strength phonon scattering,thereby optimizing carrier/phonon transport behaviors,and effectively increasing the ZT by 23.2%(from 0.99 to 1.22 at 350 K).Besides,our strategy has excellent universality confirmed by its effectiveness in improving the ZT of Bi_(2)Te_(2.7)Se_(0.3),therefore demonstrating great potential for developing low-cost and high-performance thermoelectric materials.
基金supported by the National Natural Science Foundation of China(32071721,32071720,32271814,32301530,32471806)Tianjin Excellent Special Commissioner for Agricultural Science and Technology Project(23ZYCGSN00580)+4 种基金Young Elite Scientist Sponsorship Program by Cast(No.YESS20230242)Natural Science Foundation of Tianjin(23JCZDJC00630)the China Postdoctoral Science Foundation under Grant Number(2023M741363,2023M740563)the Postdoctoral Innovation Project of Shandong Province(SDCX-ZG-202302031)China Scholarship Council(No.202408120091,No.202408120105).
文摘Carbon electrocatalyst materials based on lignocellulosic biomass with multi-components,various dimensions,high carbon content,and hierarchical morphology structures have gained great popularity in electrocatalytic applications recently.Due to the catalytic deficiency of neutral carbon atoms,the usage of single lignocellulosic-based carbon materials in electrocatalysis involving energy storage and conversion presents unsatisfactory applicability.However,atomic-level modulation of lignocellulose-based carbon materials can optimize the electronic structures,charge separation,transfer processes,and so forth,which results in substantially enhanced electrocatalytic performance of carbon-based catalysts.This paper reviews the recent advances in the rational design of lignocellulosic-based carbon materials as electrocatalysts from an atomic-level perspective,such as self/external heteroatom doping and metal modification.Then,through systematic discussion of the design principles and reaction mechanisms of the catalysts,the applications of the prepared lignocellulosic-based catalysts in rechargeable batteries and electrocatalysis are reviewed.Finally,the challenges in improving the catalytic performance of lignocellulosic-based carbon materials as electrocatalysts and the prospects in diverse applications are reviewed.This review contributes to the synthesis strategy of lignocellulose-based carbon electrocatalysts via atomic-level modulation,which in turn promotes the lignocellulose valorization for energy storage and conversion.
基金support from the National Natural Science Foundation of China through Grants 12172190,11872035,11632010,and 12302236。
文摘Atomic-scale strain mapping has become increasingly vital for investigating deformation mechanisms and the governing principles of solid materials.This is due to the significant impact of atomic-scale strain on the physical,chemical,and mechanical properties of nanomaterials that comprise functional devices such as nanoelectronics,communication devices,electromechanical systems,and sensors.The advent of advanced electron microscopes has enabled the acquisition of high-magnification images with atomic resolution,providing an exceptional platform for measuring the atomic-scale strain of solid materials.However,accurate and unified strain mapping methods and standards for evaluating atomic-scale strain distribution remain scarce.Consequently,a unified strain mapping framework is proposed for atomic-scale strain measurement.Utilizing finite deformation analysis and the least-squares mathematical method,two types of atomic-scale strain field mapping methods have been developed,including the phase analysis-based methods(PAD and PAS)and the peak matching-based strain mapping method(PMS)for high-resolution scanning transmission electron microscope images.The prototypical 2D materials,graphene and molybdenum disulfide,serve as the subjects for the strain field mapping research,conducted through both simulation and experimentation.Upon comparing the theoretical strain mapping results of single-layer graphene and molybdenum disulfide with and without defects,it is demonstrated that the proposed strain mapping methods,particularly the PMS method,can accurately describe the large deformation surrounding a significant strain gradient.
基金supported by the National Natural Science Foundation of China(Grant Nos.22278101,22068010,22168016,and 52365044)the Natural Science Foundation of Hainan Province(Grant Nos.2019RC142 and 519QN176)the Finance Science and Technology Project of Hainan Province(Grant No.ZDYF2020009).
文摘Novel and promising chloride ion batteries(CIBs)that can operate at room temperature have attracted great attentions,due to the sustainable chloride-containing resources and high theoretical energy density.To achieve the superior electrochemical properties of CIBs,the structure design of electrode materials is essential.Herein,2D NiAl-layered double hydroxide(NiAl-LDH)nanoarrays derived from Al2O3 are in-situ grafted to graphene(G)by atomic layer deposition(ALD)and hydrothermal method.The achieved NiAl-LDH@G hybrids with 2D NiAl-LDH arrays grown perpendicularly on graphene surface,can efficiently prevent the stacking of LDHs and enlarge specific surface area to provide more active sites.The NiAl-LDH@G cathode exhibits a maximum discharge capacity of 223.3 mA h g^(-1)and an excellent reversible capacity of 107 mA h g^(-1)over 500 cycles at 100 mA g^(-1)with a high coulombic efficiency around 96%,whereas pure NiAl-LDH has a discharge capacity of only 48.8 mA h g^(-1)and a coulombic efficiency(CE)of about 78%.More importantly,the NiAl-LDH@G electrode has a stable voltage at 1.9 V and an outstanding discharge capacity of higher than 72 mA h g^(-1)after 120 days.Additionally,XRD,XPS,and EDS have been employed to unveil the electrochemical reaction and Cl-storage mechanism of the NiAlLDH@G cathode in CIBs.This work opens a facile and reasonable way for improving electrochemical performance at anion-type rechargeable batteries in terms of cathode material design and mechanism interpretation.
基金supported by the Henry Royce Institute for Advanced Materials,funded through Engineering and Physical Sciences Research Council(EPSRC)grants EP/R00661X/1,EP/S019367/1,EP/P025021/1,and EP/P025498/1.
文摘Liquefied natural gas storage and transportation as well as space propulsion systems have sparked inter-est in the martensitic transformation and behaviours of 316 L stainless steels(SS)under ultra-cryogenic deformation.In this study,high-resolution transmission electron microscopy(HRTEM)and molecular dy-namics(MD)simulations were used to investigate the atomic arrangements and crystalline defects of deformation-induced γ-austenite→ε-martensite→α'-martensite and γ→α'martensitic transforma-tions in 316 L SS at 15 and 173 K.Theγ→εtransformation involves the glide of Shockley partial dislocations on(111)γplanes without a change in atomic spacing.The formation of anα'inclusion in a singleε-band is achieved by a continuous lattice distortion,accompanied by the formation of a tran-sition zone ofα'and the expansion of the average atomic spacings due to dislocation shuffling.Asα'grows further intoγ,the orientation relationship(OR)of theα'changes by lattice bending.This pro-cess follows the Bogers-Burgers-Olson-Cohen model despite it not occurring on intersecting shear bands.Stacking faults and twins can also serve as nucleation sites forα'at 173 K.We also found that direct transformation of γ→α'occurs by the glide of √6aγ[11(2)]/12 dislocations on every(111)γplane with misfit dislocations.Overall,this study provides,for the first time,insights into the atomic-scale mech-anisms of various two-step and one-step martensitic transformations induced by cryogenic deformation and corresponding local strain,enhancing our understanding of the role of martensitic transformation under ultra-cryogenic-temperature deformation in controlling the properties.
基金supported by the National Natural Science Foundation of China(No.22279118,No.22309164)the China Postdoctoral Science Foundation(No.2023M733214)+1 种基金the Young Top Talent Program of Zhongyuan-Yingcai-Jihua(No.30602674)the Special Projects of Henan Province Key Research and Development and Promotion(Science and Technology Research)(No.232102241033)。
文摘Efficient water dissociation catalysts are important for reducing the activation energy barrier of water molecules in the field of energy conversio n.Herein,symmetry-bro ken Rh ensemble induced by mandated charge was established to boost the catalytic activity toward water dissociation.As an experimental verification,the turnover frequency of 1.0-RTO_(V4)in hydrogen generation from ammonia borane hydrolysis reaches up to 2838 min-1(24828 min^(-1)depend on Rh dispersion),exceeding the benchmark set up by state-of-the-art catalysts.The transfer of mandated charge from O_(V)to Rh near O_(V)breaks the local symmetry of Rh nanoparticle and forms Rh^(γ-)(electron-aggregation Rh)-Rh interfacial atomic ensemble.This symmetry-broken Rh ensemble is the reason for the high activity of the catalyst.This work provides an effective electronic regulation strategy based on symmetry-broken atomic ensemble induced by mandated charge,designed to stimulate the limiting activity of metal catalyst in the field of next generation energy chemistry.
基金supported by the National Natural Science Foundation of China(No.21875039)the Project on the Integration of Industry-Education-Research of Fujian Province(No.2021H6020)the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(Wuhan University of Technology).
文摘The exploitation of durable and highly active Pt-based electrocatalysts for the oxygen reduction reaction(ORR)is essential for the commercialization of proton exchange membrane fuel cells(PEMFCs).Herein,we designed Pt@Pt_(3)Ti core-shell nanoparticles with atomic-controllable shells through precise thermal diffusing Ti into Pt nanoparticles for effective and durable ORR.Combining theoretical and experiment analysis,we found that the lattice strain of Pt_(3)Ti shells can be tailored by precisely controlling the thick-ness of Pt_(3)Ti shell in atomic-scale on account of the lattice constant difference between Pt and Pt_(3)Ti to optimize adsorption properties of Pt_(3)Ti for ORR intermediates,thus enhancing its performance.The Pt@Pt_(3)Ti catalyst with one-atomic Pt_(3)Ti shell(Pt@1L-Pt_(3)Ti/TiO_(2)-C)demonstrates excellent performance with mass activity of 592 mA mgpt-1 and durability nearly 19.5-fold that of commercial Pt/C with negligible decay(2%)after 30,000 potential cycles(0.6-1.0 V vs.RHE).Notably,at higher potential cycles(1.0 V-1.5 V vs.RHE),Pt@1L-Pt_(3)Ti/TiO_(2)-C also showed far superior durability than Pt/C(9.6%decayed while 54.8% for commercial Pt/C).This excellent stability is derived from the intrinsic stability of Pt_(3)Ti alloy and the confinement effect of TiO_(2)-C.The catalyst's enhancement was further confirmed in PEMFC configuration.
基金supported by the National Natural Science Foundation of China under Grant No.21933006.
文摘To eliminate distortion caused by vertical drift and illusory slopes in atomic force microscopy(AFM)imaging,a lifting-wavelet-based iterative thresholding correction method is proposed in this paper.This method achieves high-quality AFM imaging via line-by-line corrections for each distorted profile along the fast axis.The key to this line-by-line correction is to accurately simulate the profile distortion of each scanning row.Therefore,a data preprocessing approach is first developed to roughly filter out most of the height data that impairs the accuracy of distortion modeling.This process is implemented through an internal double-screening mechanism.A line-fitting method is adopted to preliminarily screen out the obvious specimens.Lifting wavelet analysis is then carried out to identify the base parts that are mistakenly filtered out as specimens so as to preserve most of the base profiles and provide a good basis for further distortion modeling.Next,an iterative thresholding algorithm is developed to precisely simulate the profile distortion.By utilizing the roughly screened base profile,the optimal threshold,which is used to screen out the pure bases suitable for distortion modeling,is determined through iteration with a specified error rule.On this basis,the profile distortion is accurately modeled through line fitting on the finely screened base data,and the correction is implemented by subtracting the modeling result from the distorted profile.Finally,the effectiveness of the proposed method is verified through experiments and applications.
基金supported by the National Natural Science Foundation of China(Nos.22371263 and U2004193)Natural Science Foundation of Henan Province(No.232300421225)。
文摘Metal nanoclusters with well-defined atomic structures offer significant promise in the field of catalysis due to their sub-nanometer size and tunable organic-inorganic hybrid structural features.Herein,we successfully synthesized an 11-core copper(Ⅰ)-alkynyl nanocluster(Cu11),which is stabilized by alkynyl ligands derived from a photosensitive rhodamine dye molecule.Notably,this Cu11cluster exhibited excellent photocatalytic hydrogen evolution activity(8.13 mmol g-1h-1)even in the absence of a mediator and noble metal co-catalyst.Furthermore,when Cu11clusters were loaded onto the surface of TiO_(2)nanosheets,the resultant Cu11@TiO_(2)nanocomposites exhibited a significant enhancement in hydrogen evolution efficiency,which is 60 times higher than that of pure TiO_(2)nanosheets.The incorporation of Cu11clusters within the Cu11@TiO_(2)effectively inhibits the recombination of photogenerated electrons and holes,thereby accelerating the charge separation and migration in the composite material.This work introduces a novel perspective for designing highly active copper cluster-based photocatalysts.
基金the National Natural Science Foundation of China(52225606,52488201)the"Fundamental Research Funds for the Central Universities".
文摘Efficient CO_(2)photoreduction to produce fuel remains a great challenge,due to the fast recombination of photogenerated charge carriers and the lack of effective reactive sites in the developed photocatalysts.Herein,single Co atoms(Co_(SA))were highly dispersed on hydrothermally synthesized BiOCl nanosheets(BOC)by a facile two-step electrostatic self-assembly and pyrolysis method.The obtained Co_(SA)-BOC could be performed for efficient CO_(2)photoreduction to stoichiometrically produce CO and O_(2)at the ratio of 2:1,with the CO evolution rate reaching 45.93 μmol g^(-1)h^(-1),~4 times that of the pristine BOC.This distinctly improved photocatalytic performance for Co_(SA)-BOC should benefit from the introduction of atomically dispersed Co–O_(4)coordination structures,which could accelerate the migration of photogenerated charge carriers to surface by creating an impurity energy level in the forbidden band,and act as the reactive sites to deliver the photogenerated electrons to activate CO_(2)molecules for CO production.This work provides a facile and reliable strategy to highly disperse single atoms on low-dimensional semiconductors for efficient CO_(2)photoreduction to selectively produce CO.
