The core-shell structure in bulk TiNb binary alloy was designed and studied by phase-field simulations,where various core-shell structures were obtained by precise control of the initial and boundary conditions of the...The core-shell structure in bulk TiNb binary alloy was designed and studied by phase-field simulations,where various core-shell structures were obtained by precise control of the initial and boundary conditions of the TiNb binary alloy system during spinodal decomposition,and then the formation mechanism of core-shell structure was revealed.In addition,the influences of initial temperature gradient,average temperature,and initial concentration distribution of the system on the core-shell structure were investigated.Results show that the initial concentration gradient is the key factor for forming the core-shell structure.Besides,larger initial temperature gradient and higher average temperature can promote the formation of core-shell structure,which can be stabilized by adjusting the initial concentration distribution of the Nb-rich region in TiNb binary alloy.As a theoretical basis,this research provides a novel and simple strategy for the preparation of TiNb-based alloys and other materials with peculiar core-shell structures and desirable mechanical and physical properties.展开更多
In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Seve...In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.展开更多
It is an important way to improve the efficiency of solar cells by using the special microstructures of surface.In this work,a pyramid-silicon nanowires (pyramidSiNWs) binary structure was prepared on the silicon surf...It is an important way to improve the efficiency of solar cells by using the special microstructures of surface.In this work,a pyramid-silicon nanowires (pyramidSiNWs) binary structure was prepared on the silicon surfaces with the metal-assisted chemical etching (MACE) method.Scanning electron microscope (SEM) was used to observe the micromorphology of the pyramid-SiNWs binary structure.The formation mechanism of the binary structure was discussed.The role of Ag nanoparticles in MACE is considered to be the template and the catalyzer.The optical reflectivity of the silicon surfaces was studied with ultraviolet-visible (UV-Vis) spectrophotometer.Compared with the fiat silicon surface and the simple pyramidal structure,the silicon surfaces with the pyramid-SiNWs binary structure achieve a much lower reflectance in a wide range of wavelength.The effect of etching time as a parameter on the reflectivity was also discussed.展开更多
The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(...The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(y)Mn_(1-y)[Fe(CN)_(6)]·nH_(2)O(KFeMnHCF)nanocuboid,with the concentration-gradient(CG)structure is designed as a high-performance cathode for AKIB.Internal the CG-KFeMnHCF nanocuboids,the manganese content gradually decreases from the interior to the surface and the iron content changes reverse,resulting in the concentration-gradient structure.Both experimental and finite element simulation(FEA)results demonstrate the lower internal stress and better mechanical characteristics of CG structured nanocuboid than the homogenous structured one upon ion intercalation/deintercalation processes.Meanwhile,the electrochemical testing and theoretical calculation(DFT)results disclose the substitution of Fe to Mn in the KMnHCF crystal results in the enhanced electronic conductivity,potassium migration and electrochemical kinetics.Taken both advantages from the well-designed architecture and optimized crystal structure,the CG-KFeMnHCF achieves the superior rate capability and ultrahigh stability in aqueous potassium ion system.In particular,the CG-KFe_(0.31)Mn_(0.69)HCF achieves the best comprehensive properties among all the samples.The full AKIBs based on CG-KFe_(0.31)Mn_(0.69)HCF cathode achieves the high energy density(83 Wh kg^(-1)),superior power density,high capacity retention(83%)over high-rate long-term cycles,good adaptation to a wide temperature range(-20 to 40℃)and high reliability even under outside deformations.Therefore,this work not only provides a new clue to design the highperformance cathode,but also promotes the applications of AKIBs for diverse electronics and wide working environments.展开更多
Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water...Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.展开更多
Although the Ostwald ripening approach is often utilized to manufacture single hollow metal oxide,constructing hollow binary oxide heterostructures as potent photoelectrochemical(PEC)catalysts is still obscure and cha...Although the Ostwald ripening approach is often utilized to manufacture single hollow metal oxide,constructing hollow binary oxide heterostructures as potent photoelectrochemical(PEC)catalysts is still obscure and challenging.Herein,we reveal a general strategy for fabricating hollow binary oxides heterostructures(Co_(3)O_(4)-δ-MnO_(2)and Co_(3)O_(4)–SnO_(2))utilizing Ostwald ripening.Hollow Co_(3)O_(4)-δ-MnO_(2)nano-network with the structure evolution process was systematically explored through experimental and theoretical tools,identifying the origin of hollow binary oxides due to the interfaces acting as landing sites for their growth.In addition,the structural evolution,from hollow Co_(3)O_(4)-δ-MnO_(2)to Co_(3)O_(4)-α-MnO_(2),can be observed when the time of secondary hydrothermal reaches 96 h due to the topotactic layer-to-tunnel transition process.Notably,optimized Co_(3)O_(4)-δ-MnO_(2)-48 exhibits a superior PEC degradation efficiency of 96.42%and excellent durability(20,000 min)under harsh acid conditions,attributed to the massive hollow structures'vast surface area for high intently active species.Furthermore,density functional theory simulations elucidated the Co_(3)O_(4)-δ-MnO_(2)’electron-deficient surface and high d-band center(Co_(3)O_(4)-δ-MnO_(2),-1.06;Co_(3)O_(4)-α-MnO_(2),-1.49),strengthening the interaction between the catalyst's surface and active species and prolonging the lifetime of active species ofO_(2)and 1 O_(2).This work not only demonstrates superior PEC degradation efficiency of hollow Co_(3)O_(4)-δ-MnO_(2)for practical use but also lays the cornerstone for constructing hollow binary oxides heterostructures through Ostwald ripening.展开更多
A binary available bit rate （ABR） scheme based on discrete-time variable structure control （DVSC） theory is proposed to solve the problem of asynchronous transfer mode （ATM） networks congestion in this paper. A ...A binary available bit rate （ABR） scheme based on discrete-time variable structure control （DVSC） theory is proposed to solve the problem of asynchronous transfer mode （ATM） networks congestion in this paper. A discrete-time system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality （LMI）. In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate （ACR） and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms.展开更多
In this paper the electronic structure of A1B2-type USi2 has been explored using DFT, DFT＋U and hybrid functional （HSE） methods. It reveals that c/a has great effect on the electronic structure, particularly thefor...In this paper the electronic structure of A1B2-type USi2 has been explored using DFT, DFT＋U and hybrid functional （HSE） methods. It reveals that c/a has great effect on the electronic structure, particularly theforbitals, and there exists strong hybridization between the Si-p and U-d orbitals in A1B2-type USi2. These calculations uncover that there exists similarities on the crystal structure and the electronic structure between AIB2-type USi2 and UaSis. Present calculations provide a further insight on the U3Si5, a heavy-fermion system.展开更多
The designing,encodings and an instance of simulation of a binary tree for DNA computer were proposed,which utilizes the method of biology to complete inserting and deleting of the binary tree. Firstly,DNA encodings f...The designing,encodings and an instance of simulation of a binary tree for DNA computer were proposed,which utilizes the method of biology to complete inserting and deleting of the binary tree. Firstly,DNA encodings for storage and all elements of the binary tree were completely given out. Then, the implementations of all bio-operations in DNA computer were described. Finally, to prove the feasibility of this method, an actual binary tree with detailed nucleotide encodings was introduced. The process of an algorithm implemented on this binary tree was demonstrated. Based on this method, more other data structures in DNA computer can be developed.展开更多
A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexi...A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.展开更多
Using first-principle calculations, we investigate the mechanical, structural, and electronic properties and formation energy of 25 kinds of Ⅲ–V binary monolayers in detail. A relative radius of the binary compound ...Using first-principle calculations, we investigate the mechanical, structural, and electronic properties and formation energy of 25 kinds of Ⅲ–V binary monolayers in detail. A relative radius of the binary compound according to the atomic number in the periodic table is defined, and based on the definition, the 25 kinds of Ⅲ–V binary compounds are exactly located at a symmetric position in a symmetric matrix. The mechanical properties and band gaps are found to be very dependent on relative radius, while the effective mass of holes and electrons are found to be less dependent. A linear function between Young’s modulus and formation energy is fitted with a linear relation in this paper. The change regularity of physical properties of B–V(V = P, As, Sb, Bi) and Ⅲ–N(Ⅲ = Al, Ga, In, Tl) are found to be very different from those of other Ⅲ–V binary compounds.展开更多
A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was develo...A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.展开更多
Existing strength criteria are mostly formulated to describe the mechanical properties of reconstituted soils. However, the engineering characteristics of structured soils are different from those of reconstituted soi...Existing strength criteria are mostly formulated to describe the mechanical properties of reconstituted soils. However, the engineering characteristics of structured soils are different from those of reconstituted soils in many aspects, especially in their strength properties, Thus, the influence of soil structure （bonding and fabric） on the mechanical properties of structured soils cannot be correctly described, By analyzing the breakage mechanism of natural soils, the structured soils can be conceptualized as binary medium materials consisting of bonded blocks and weakened bands. On this basis, a new strength criterion is pro- posed for structured soils, The expressions of the strength criterion on both meridian and deviator planes are given to describe the strength properties of structured soils on these planes. The proposed strength criterion is compared with available test data under conventional and true triaxial stress conditions in the literature. It is observed that the proposed strength criterion agrees well with the test data.展开更多
The frequency of heterogeneous nucleation during the solidification of Al-Sibinary alloy was estimated by comparing experimentally obtained macrostructures of castings withnumerically simulated ones. A molten alloy wa...The frequency of heterogeneous nucleation during the solidification of Al-Sibinary alloy was estimated by comparing experimentally obtained macrostructures of castings withnumerically simulated ones. A molten alloy was unidirectionally solidified from a water-cooledcopper chill in an adiabatic mold. The location of columnar to equiaxed transition (CET) in thesolidified alloy ingot was measured. A numerical simulation for grain structure formation based onthe Monte Carlo method was carried out, and the frequency of heterogeneous nucleation in the alloywas evaluated by producing similar structure with the experimental one. The frequency ofheterogeneous nucleation was expressed as a probabilistic function with an exponential form ofundercooling that deter-mines the probability of nucleation event in the simulation. The value ofthe exponent is regarded as the nucleation parameter. The nucleation parameter of Al-Si binary alloyvaried with initial Si content.展开更多
A simple and effective self-molten-polymerization strategy utilizing the molten metal salts from heated solid metal salt sources as the solvents to dissolve a self-polymerizable monomer,which acted as a mingling agent...A simple and effective self-molten-polymerization strategy utilizing the molten metal salts from heated solid metal salt sources as the solvents to dissolve a self-polymerizable monomer,which acted as a mingling agent,was successfully applied to homogeneously synthesize a series of highly defected manganese/samarium(Mn/Sm-x,where x represents the molar ratio of Mn to Sm)hybrid bimetallic oxides with a mesoporous structure.The values of T50 and T90 over Mn/Sm-2 were 206℃and 247℃,respectively,for toluene conversion,as well as 213℃and 273℃for CO_(2) yield under saturated vapor with a weight hourly space velocity of 60000 ml g^(−1)h^(−1),which were far superior to the performances of Mn/Cu-2(233℃and 274℃;237℃and 300℃)and MnO_(x)(242℃and 294℃;255℃and 315℃).Meanwhile,the most active catalyst Mn/Sm-4 exhibited complete mineralization of chlorobenzene under saturated vapor and a weight hourly space velocity of 60000 ml g^(−1)h^(−1)at 350℃.In addition,the Mn/Sm-4 catalyst also showed a high TOFMn value(8.35×10^(−6)s^(−1))at 140℃for toluene oxidation and good stability for the catalytic oxidation of toluene and chlorobenzene under a long-term test running for 200 h of uninterrupted reaction.The XRD,Raman,N_(2)adsorption–desorption,FESEM,XPS,O2-TPD and H_(2)-TPR results confirmed that more surface defects and surface oxygen vacancies were introduced into MnO_(x)using proper doping with Sm.Combined with the in situ DRIFTS and on-line MS measurements,the mechanism for chlorobenzene oxidation over Mn/Sm-4 was also revealed.This work presents an important interpretation for developing improved catalysts to control air pollution.展开更多
In order to assist in predicting the properties of molten cryolite-alumina electrolytes widely used in the Hall-Héroult process,the micro-structure of the molten binary system was investigated by in situ high tem...In order to assist in predicting the properties of molten cryolite-alumina electrolytes widely used in the Hall-Héroult process,the micro-structure of the molten binary system was investigated by in situ high temperature Raman spectroscopy from room temperature to 1273 K under an argon atmosphere.The symmetric stretching vibrational wavenumbers of possible clusters in the molten system were further calculated through quantum chemistry ab initio simulations and compared with the experimental Raman spectra of the molten system.The molten K_(3)AlF_(6)-Al_(2)O_(3)system was found to consist of[AlF_(5)]^(2-),[AlF_(6)]^(3-),[Al_(2)OF_(6)]^(2-)and[Al_(2)O_(2)F_(4)]^(2-)clusters.With the increasing addition of Al_(2)O_(3)to molten K_(3)AlF_(6),the structure of six-coordinated Al atoms connected by terminal fluorine is partly believed to evolve into a structure of two four-coordinated Al atoms connected by single-bridging oxygen.The mole percentage of the species in the melt was also calculated from the experimental Raman spectra.As the Al_(2)O_(3)content increased from 0 to 8.0 wt%,the content of[Al_(2)OF_(6)]^(2-)in the melt was found to increase swiftly from 0 to 33.0 mol%,while the[Al_(2)O_(2)F_(4)]^(2-)content decreased after reaching a maximum of 1.5 mol%.展开更多
基金National Natural Science Foundation of China(12372152)Guangdong Basic and Applied Basic Research Foundation(2023A1515011819,2024A1515012469)Shandong Provincial Natural Science Foundation(ZR2023MA058)。
文摘The core-shell structure in bulk TiNb binary alloy was designed and studied by phase-field simulations,where various core-shell structures were obtained by precise control of the initial and boundary conditions of the TiNb binary alloy system during spinodal decomposition,and then the formation mechanism of core-shell structure was revealed.In addition,the influences of initial temperature gradient,average temperature,and initial concentration distribution of the system on the core-shell structure were investigated.Results show that the initial concentration gradient is the key factor for forming the core-shell structure.Besides,larger initial temperature gradient and higher average temperature can promote the formation of core-shell structure,which can be stabilized by adjusting the initial concentration distribution of the Nb-rich region in TiNb binary alloy.As a theoretical basis,this research provides a novel and simple strategy for the preparation of TiNb-based alloys and other materials with peculiar core-shell structures and desirable mechanical and physical properties.
基金supported by grants from the Natural Science Foundation of China(Nos.61275167,60878036and 60178023)the Basic Research Project of Shenzhen(Nos.JCYJ20130329103020637,JCYJ20120613112628842,JCYJ20140418095735591 and JC201005280533A)
文摘In this paper, a novel method of a subwavelength binary simple periodic rectangular structure is presented to realize even beam splitting by combining the rigorous couple-wave analysis with the genetic algorithm. Several even splitters in the terahertz region were designed and one of the silicon-based beam splitters designed to separate one incident beam into four emergent beams has total efficiency up to 92.23 %. Zero-order diffraction efficiency was reduced to less than 0.192 % and the error of uniformity decreased to 6.51 9 10-6. These results break the limitation of even beam splitting based on the traditional scalar theory. In addition, the effects of the incident angle, wavelength, as well as the polarizing angle on the diffraction efficiency and uniformity were also investigated.
基金financially supported by the National Natural Science Foundation of China (Nos. 51032002 and 11274028)
文摘It is an important way to improve the efficiency of solar cells by using the special microstructures of surface.In this work,a pyramid-silicon nanowires (pyramidSiNWs) binary structure was prepared on the silicon surfaces with the metal-assisted chemical etching (MACE) method.Scanning electron microscope (SEM) was used to observe the micromorphology of the pyramid-SiNWs binary structure.The formation mechanism of the binary structure was discussed.The role of Ag nanoparticles in MACE is considered to be the template and the catalyzer.The optical reflectivity of the silicon surfaces was studied with ultraviolet-visible (UV-Vis) spectrophotometer.Compared with the fiat silicon surface and the simple pyramidal structure,the silicon surfaces with the pyramid-SiNWs binary structure achieve a much lower reflectance in a wide range of wavelength.The effect of etching time as a parameter on the reflectivity was also discussed.
基金supported by the Innovation Foundation of Graduate Student of Harbin Normal University(Grant No.HSDSSCX2020-18)the Natural Science Foundation of Heilongjiang Province,China(Grant No.TD2020B001)the Opening Project of State Key Laboratory of Advanced Chemical Power Sources(Grant No.SKL-ACPS-C-25)。
文摘The exploration of low-strain and high-performance electrode is a crucial issue for aqueous potassiumion battery(AKIB).Herein,a novel potassium mediated iron/manganese binary hexacyanoferrate nanocuboid,i.e.,K_(x)Fe_(y)Mn_(1-y)[Fe(CN)_(6)]·nH_(2)O(KFeMnHCF)nanocuboid,with the concentration-gradient(CG)structure is designed as a high-performance cathode for AKIB.Internal the CG-KFeMnHCF nanocuboids,the manganese content gradually decreases from the interior to the surface and the iron content changes reverse,resulting in the concentration-gradient structure.Both experimental and finite element simulation(FEA)results demonstrate the lower internal stress and better mechanical characteristics of CG structured nanocuboid than the homogenous structured one upon ion intercalation/deintercalation processes.Meanwhile,the electrochemical testing and theoretical calculation(DFT)results disclose the substitution of Fe to Mn in the KMnHCF crystal results in the enhanced electronic conductivity,potassium migration and electrochemical kinetics.Taken both advantages from the well-designed architecture and optimized crystal structure,the CG-KFeMnHCF achieves the superior rate capability and ultrahigh stability in aqueous potassium ion system.In particular,the CG-KFe_(0.31)Mn_(0.69)HCF achieves the best comprehensive properties among all the samples.The full AKIBs based on CG-KFe_(0.31)Mn_(0.69)HCF cathode achieves the high energy density(83 Wh kg^(-1)),superior power density,high capacity retention(83%)over high-rate long-term cycles,good adaptation to a wide temperature range(-20 to 40℃)and high reliability even under outside deformations.Therefore,this work not only provides a new clue to design the highperformance cathode,but also promotes the applications of AKIBs for diverse electronics and wide working environments.
基金the National Natural Science Foundation of China(Nos.52072151,52171211,52102253,52271218,U22A20145)the Jinan Independent Innovative Team(2020GXRC015)+1 种基金the Major Program of Shandong Province Natural Science Foundation(ZR2021ZD05)the Science and Technology Program of University of Jinan(XKY2119).
文摘Focused exploration of earth-abundant and cost-efficient non-noble metal electrocatalysts with superior hydrogen evolution reaction(HER)performance is very important for large-scale and efficient electrolysis of water.Herein,a sandwich composite structure(designed as MS-Mo2C@NCNS)ofβ-Mo2C hollow nanotubes(HNT)and N-doped carbon nanosheets(NCNS)is designed and prepared using a binary NaCl–KCl molten salt(MS)strategy for HER.The temperature-dominant Kirkendall formation mechanism is tentatively proposed for such a three-dimensional hierarchical framework.Due to its attractive structure and componential synergism,MS-Mo2C@NCNS exposes more effective active sites,confers robust structural stability,and shows significant electrocatalytic activity/stability in HER,with a current density of 10 mA cm-2 and an overpotential of only 98 mV in 1 M KOH.Density functional theory calculations point to the synergistic effect of Mo2C HNT and NCNS,leading to enhanced electronic transport and suitable adsorption free energies of H*(ΔGH*)on the surface of electroactive Mo2C.More significantly,the MS-assisted synthetic methodology here provides an enormous perspective for the commercial development of highly active non-noble metal electrocatalysts toward efficient hydrogen evolution.
基金supported by the National Natural Science Foundation of China(21875026,21878031)the Program for Liaoning Excellent Talents in University(LR2014013)+4 种基金the Science and Technology Foundation of Liaoning Province(No.201602052)the Natural Science Foundation of Liaoning Province(No.20170520427)supported by Liaoning Revitalization Talents Program(XLYC1802124)sponsored by the Liaoning BaiQianWan Talents Program,the scientific research fund of the educational department of Liaoning province(J2019013)The Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science(Project number:2019JH3/30100034,contract number:2019010278-JH3/301).
文摘Although the Ostwald ripening approach is often utilized to manufacture single hollow metal oxide,constructing hollow binary oxide heterostructures as potent photoelectrochemical(PEC)catalysts is still obscure and challenging.Herein,we reveal a general strategy for fabricating hollow binary oxides heterostructures(Co_(3)O_(4)-δ-MnO_(2)and Co_(3)O_(4)–SnO_(2))utilizing Ostwald ripening.Hollow Co_(3)O_(4)-δ-MnO_(2)nano-network with the structure evolution process was systematically explored through experimental and theoretical tools,identifying the origin of hollow binary oxides due to the interfaces acting as landing sites for their growth.In addition,the structural evolution,from hollow Co_(3)O_(4)-δ-MnO_(2)to Co_(3)O_(4)-α-MnO_(2),can be observed when the time of secondary hydrothermal reaches 96 h due to the topotactic layer-to-tunnel transition process.Notably,optimized Co_(3)O_(4)-δ-MnO_(2)-48 exhibits a superior PEC degradation efficiency of 96.42%and excellent durability(20,000 min)under harsh acid conditions,attributed to the massive hollow structures'vast surface area for high intently active species.Furthermore,density functional theory simulations elucidated the Co_(3)O_(4)-δ-MnO_(2)’electron-deficient surface and high d-band center(Co_(3)O_(4)-δ-MnO_(2),-1.06;Co_(3)O_(4)-α-MnO_(2),-1.49),strengthening the interaction between the catalyst's surface and active species and prolonging the lifetime of active species ofO_(2)and 1 O_(2).This work not only demonstrates superior PEC degradation efficiency of hollow Co_(3)O_(4)-δ-MnO_(2)for practical use but also lays the cornerstone for constructing hollow binary oxides heterostructures through Ostwald ripening.
基金the National Natural Science Foundation of China (No.60274009)Specialized Research Fund for the DoctoralProgram of Higher Education (No.20020145007)
文摘A binary available bit rate （ABR） scheme based on discrete-time variable structure control （DVSC） theory is proposed to solve the problem of asynchronous transfer mode （ATM） networks congestion in this paper. A discrete-time system model with uncertainty is introduced to depict the time-varying ATM networks. Based on the system model, an asymptotically stable sliding surface is designed by linear matrix inequality （LMI）. In addition, a novel discrete-time reaching law that can obviously reduce chatter is also put forward. The proposed discrete-time variable structure controller can effectively constrain the oscillation of allowed cell rate （ACR） and the queue length in a router. Moreover, the controller is self-adaptive against the uncertainty in the system. Simulations are done in different scenarios. The results demonstrate that the controller has better stability and robustness than the traditional binary flow controller, so it is good for adequately exerting the simplicity of binary flow control mechanisms.
文摘In this paper the electronic structure of A1B2-type USi2 has been explored using DFT, DFT＋U and hybrid functional （HSE） methods. It reveals that c/a has great effect on the electronic structure, particularly theforbitals, and there exists strong hybridization between the Si-p and U-d orbitals in A1B2-type USi2. These calculations uncover that there exists similarities on the crystal structure and the electronic structure between AIB2-type USi2 and UaSis. Present calculations provide a further insight on the U3Si5, a heavy-fermion system.
文摘The designing,encodings and an instance of simulation of a binary tree for DNA computer were proposed,which utilizes the method of biology to complete inserting and deleting of the binary tree. Firstly,DNA encodings for storage and all elements of the binary tree were completely given out. Then, the implementations of all bio-operations in DNA computer were described. Finally, to prove the feasibility of this method, an actual binary tree with detailed nucleotide encodings was introduced. The process of an algorithm implemented on this binary tree was demonstrated. Based on this method, more other data structures in DNA computer can be developed.
基金Project supported by Publication Foundation of National Science and Technology Academic Books of China
文摘A universal thermodynamic model of calculating mass action concentrations for structural units or ion couples in ternary and binary strong electrolyte aqueous solution was developed based on the ion and molecule coexistence theory and verified in four kinds of binary aqueous solutions and two kinds of ternary aqueous solutions. The calculated mass action concentrations of structural units or ion couples in four binary aqueous solutions and two ternary solutions at 298.15 K have good agreement with the reported activity data from literatures after shifting the standard state and concentration unit. Therefore, the calculated mass action concentrations of structural units or ion couples from the developed universal thermodynamic model for ternary and binary aqueous solutions can be applied to predict reaction ability of components in ternary and binary strong electrolyte aqueous solutions. It is also proved that the assumptions applied in the developed thermodynamic model are correct and reasonable, i.e., strong electrolyte aqueous solution is composed of cations and anions as simple ions, H2O as simple molecule and other hydrous salt compounds as complex molecules. The calculated mass action concentrations of structural units or ion couples in ternary and binary strong electrolyte aqueous solutions strictly follow the mass action law.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61564002 and 11664005)the Guizhou Normal University Innovation and Entrepreneurship Education Research Center Foundation(Grant No.0418010)the Joint Foundation of Guizhou Normal University(Grant No.7341)
文摘Using first-principle calculations, we investigate the mechanical, structural, and electronic properties and formation energy of 25 kinds of Ⅲ–V binary monolayers in detail. A relative radius of the binary compound according to the atomic number in the periodic table is defined, and based on the definition, the 25 kinds of Ⅲ–V binary compounds are exactly located at a symmetric position in a symmetric matrix. The mechanical properties and band gaps are found to be very dependent on relative radius, while the effective mass of holes and electrons are found to be less dependent. A linear function between Young’s modulus and formation energy is fitted with a linear relation in this paper. The change regularity of physical properties of B–V(V = P, As, Sb, Bi) and Ⅲ–N(Ⅲ = Al, Ga, In, Tl) are found to be very different from those of other Ⅲ–V binary compounds.
基金supported by the Publication Foundation of China National Science and Technology Academic Books
文摘A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.
文摘Existing strength criteria are mostly formulated to describe the mechanical properties of reconstituted soils. However, the engineering characteristics of structured soils are different from those of reconstituted soils in many aspects, especially in their strength properties, Thus, the influence of soil structure （bonding and fabric） on the mechanical properties of structured soils cannot be correctly described, By analyzing the breakage mechanism of natural soils, the structured soils can be conceptualized as binary medium materials consisting of bonded blocks and weakened bands. On this basis, a new strength criterion is pro- posed for structured soils, The expressions of the strength criterion on both meridian and deviator planes are given to describe the strength properties of structured soils on these planes. The proposed strength criterion is compared with available test data under conventional and true triaxial stress conditions in the literature. It is observed that the proposed strength criterion agrees well with the test data.
文摘The frequency of heterogeneous nucleation during the solidification of Al-Sibinary alloy was estimated by comparing experimentally obtained macrostructures of castings withnumerically simulated ones. A molten alloy was unidirectionally solidified from a water-cooledcopper chill in an adiabatic mold. The location of columnar to equiaxed transition (CET) in thesolidified alloy ingot was measured. A numerical simulation for grain structure formation based onthe Monte Carlo method was carried out, and the frequency of heterogeneous nucleation in the alloywas evaluated by producing similar structure with the experimental one. The frequency ofheterogeneous nucleation was expressed as a probabilistic function with an exponential form ofundercooling that deter-mines the probability of nucleation event in the simulation. The value ofthe exponent is regarded as the nucleation parameter. The nucleation parameter of Al-Si binary alloyvaried with initial Si content.
基金the National Natural Science Foundation of China(Grant No:21876107,21507082,21377083)the special development fund of the Shanghai Zhangjiang National Innovation Demonstration Zone(Grant No:201505-Q P-B108-006)for their financial support.
文摘A simple and effective self-molten-polymerization strategy utilizing the molten metal salts from heated solid metal salt sources as the solvents to dissolve a self-polymerizable monomer,which acted as a mingling agent,was successfully applied to homogeneously synthesize a series of highly defected manganese/samarium(Mn/Sm-x,where x represents the molar ratio of Mn to Sm)hybrid bimetallic oxides with a mesoporous structure.The values of T50 and T90 over Mn/Sm-2 were 206℃and 247℃,respectively,for toluene conversion,as well as 213℃and 273℃for CO_(2) yield under saturated vapor with a weight hourly space velocity of 60000 ml g^(−1)h^(−1),which were far superior to the performances of Mn/Cu-2(233℃and 274℃;237℃and 300℃)and MnO_(x)(242℃and 294℃;255℃and 315℃).Meanwhile,the most active catalyst Mn/Sm-4 exhibited complete mineralization of chlorobenzene under saturated vapor and a weight hourly space velocity of 60000 ml g^(−1)h^(−1)at 350℃.In addition,the Mn/Sm-4 catalyst also showed a high TOFMn value(8.35×10^(−6)s^(−1))at 140℃for toluene oxidation and good stability for the catalytic oxidation of toluene and chlorobenzene under a long-term test running for 200 h of uninterrupted reaction.The XRD,Raman,N_(2)adsorption–desorption,FESEM,XPS,O2-TPD and H_(2)-TPR results confirmed that more surface defects and surface oxygen vacancies were introduced into MnO_(x)using proper doping with Sm.Combined with the in situ DRIFTS and on-line MS measurements,the mechanism for chlorobenzene oxidation over Mn/Sm-4 was also revealed.This work presents an important interpretation for developing improved catalysts to control air pollution.
基金financial support from the National Natural Science Foundation of China(grant numbers 50932005 and 21773152)Shanghai Committee of Science and Technology Fund,China(grant number 12520709200)+3 种基金Open Project Program of the State Key Laboratory of Advanced Special Steel,Shanghai University,China(grant number SKLASS2015-01,SKLASS2017-02)Independent Research and Development Project of State Key Laboratory of Advanced Special Steel,Shanghai University(SKLASS 2016-Z01)Program of Introducing Talents of Discipline to Universities(Supported by 111 Project)Special Fund Project of Shanghai Municipality for Science and Technology Development(YDZX20173100001316).
文摘In order to assist in predicting the properties of molten cryolite-alumina electrolytes widely used in the Hall-Héroult process,the micro-structure of the molten binary system was investigated by in situ high temperature Raman spectroscopy from room temperature to 1273 K under an argon atmosphere.The symmetric stretching vibrational wavenumbers of possible clusters in the molten system were further calculated through quantum chemistry ab initio simulations and compared with the experimental Raman spectra of the molten system.The molten K_(3)AlF_(6)-Al_(2)O_(3)system was found to consist of[AlF_(5)]^(2-),[AlF_(6)]^(3-),[Al_(2)OF_(6)]^(2-)and[Al_(2)O_(2)F_(4)]^(2-)clusters.With the increasing addition of Al_(2)O_(3)to molten K_(3)AlF_(6),the structure of six-coordinated Al atoms connected by terminal fluorine is partly believed to evolve into a structure of two four-coordinated Al atoms connected by single-bridging oxygen.The mole percentage of the species in the melt was also calculated from the experimental Raman spectra.As the Al_(2)O_(3)content increased from 0 to 8.0 wt%,the content of[Al_(2)OF_(6)]^(2-)in the melt was found to increase swiftly from 0 to 33.0 mol%,while the[Al_(2)O_(2)F_(4)]^(2-)content decreased after reaching a maximum of 1.5 mol%.
