Low-temperatures synthesis of CuS nanospheres as cathode material for magnesium second batteries

Rechargeable magnesium batteries(RMBs),as one of the most promising candidates for efficient energy storage devices with high energy,power density and high safety,have attracted increasing attention.However,searching for suitable cathode materials with fast diffusion kinetics and exploring their magnesium storage mechanisms remains a great challenge.Cu S submicron spheres,made by a facile low-temperature synthesis strategy,were applied as the high-performance cathode for RMBs in this work,which can deliver a high specific capacity of 396mAh g^(-1)at 20 mA g^(-1) and a remarkable rate capacity of 250 m Ah g^(-1)at 1000 mA g^(-1).The excellent rate performance can be assigned to the nano needle-like particles on the surface of Cu S submicron spheres,which can facilitate the diffusion kinetics of Mg^(2+).Further storage mechanism investigations illustrate that the Cu S cathodes experience a two-step conversion reaction controlled by diffusion during the electrochemical reaction process.This work could make a contribution to the study of the enhancement of diffusion kinetics of Mg2+and the reaction mechanism of RMBs.

Multiscale strain alleviation of Ni-rich cathode guided by in situ environmental transmission electron microscopy during the solid-state synthesis

Ni-rich layered oxides are one of the most promising cathode materials for Li-ion batteries due to their high energy density.However,the chemomechanical breakdown and capacity degradation associated with the anisotropic lattice evolution during lithiation/delithiation hinders its practical application.Herein,by utilizing the in situ environmental transmission electron microscopy(ETEM),we provide a real time nanoscale characterization of high temperature solid-state synthesis of LiNi_(0.8)CO_(0.1)Mn_(0.1)O_(2)(NCM811) cathode,and unprecedentedly reveal the strain/stress formation and morphological evolution mechanism of primary/second ary particles,as well as their influence on electrochemical performance.We show that stress inhomogeneity during solid-state synthesis will lead to both primary/secondary particle pulverization and new grain boundary initiation,which are detrimental to cathode cycling stability and rate performance.Aiming to alleviate this multiscale strain during solid-state synthesis,we introduced a calcination scheme that effectively relieves the stress during the synthesis,thus mitigating the primary/secondary particle crack and the detrimental grain boundaries formation,which in turn improves the cathode structural integrity and Li-ion transport kinetics for long-life and high-rate electrochemical performance.This work remarkably advances the fundamental understanding on mechanochemical properties of transition metal oxide cathode with solid-state synthesis and provides a unified guide for optimization the Ni-rich oxide cathode.

Low-Temperature Synthesis of Nano-AlN Based on Solid Nitrogen Source by Plasma-Assisted Ball Milling

Plasma-assisted ball milling was carried out on the Al+C3H6N6 system and Al+C_(4)H_(4)N_(4) system,respectively.The phase structure,functional groups and synthesis mechanism were analyzed by XRD and FT-IR,and the differences in the synthesis process of nano-AlN with different solid nitrogen sources were discussed.The results show that C3H6N6 has a stable triazine ring structure,and its chemical bond is firm and difficult to break,so AlN cannot be synthesized directly by solid-solid reaction at room temperature.However,there are a large number of nitrile groups(-CN)and amino groups(-NH_(2))in C_(4)H_(4)N_(4) molecules.Under the combined action of plasma bombardment and mechanical energy activation,C_(4)H_(4)N_(4) molecules undergo polycondensation and deamination,so that the ball milling tank is filled with a large number of active nitrogen-containing groups such as N=,≡N,etc.These groups and ball milling activated Al can synthesize nano-AlN at room temperature,with a conversion rate of 92%.SEM,DSC/TG analysis showed that the powder obtained by ball milling was formed by soft agglomeration of many fine primary particles about 50–80 nm.The surface morphology of the powder was loose and porous,and it had strong activity.After annealing at 800℃,the conversion rate of the Al+C_(4)H_(4)N_(4) system reached 99%.

Dielectric barrier discharge plasma-assisted catalytic ammonia synthesis:synergistic effect of Ni-MOF-74 catalyst and nanosecond pulsed plasma

Ammonia is one of the most important chemical raw materials in both manufacture and life of human.Traditionally Haber-Bosch method for ammonia synthesis involves high temperature and high pressure conditions,leading to significant energy consumption and environmental pollution.Non-thermal plasma(NTP) is a promising alternative approach to ammonia synthesis at low temperature and atmospheric pressure.In this study,the synergistic effect of nanosecond pulsed dielectric barrier discharge(np-DBD) and Ni-MOF-74 catalyst was investigated in ammonia synthesis by utilizing nitrogen and hydrogen as feedstock.The results demonstrated that the plasma catalytic-synthesis process parameters play a crucial role in the synthesis process of ammonia.The highest ammonia synthesis rate of 5145.16 μmol·g^(-1)·h^(-1)with an energy efficiency of 1.27 g·kWh^(-1)was observed in the presence of the Ni-MOF-74 catalyst,which was3.7 times higher than that without Ni-MOF-74 catalyst.The synergistic effect of Ni-MOF-74catalyst and nanosecond pulsed plasma was explored by in-situ plasma discharge diagnostics.

Promoting effect of polyoxyethylene octylphenol ether on Cu/ZnO catalysts for low-temperature methanol synthesis

Cu/ZnO catalysts were prepared by the co-precipitation method with the addition of OP-10 （polyoxyethylene octylphenol ether） and were chemically and structurally characterized by means of XRD, BET, H2-TPR, CO-TPD and N20-titration. The effect of OP-10 addition on the activity of Cu/ZnO for the slurry phase methanol synthesis at 150℃ was evaluated. The results showed that Cu/ZnO prepared with addition of 8% OP-10 （denoted as C8） exhibited the promoted activity for the methanol synthesis. The conversion of CO and the STY （space time yield） of methanol were 42.5% and 74.6% higher than those of Cu/ZnO prepared without addition of OP-10 （denoted as CO）, respectively. The precursor of C8 contained more aurichalcite and rosasite, and the concerted effect of Cu-Zn in C8 was found to be stronger than that in CO. Compared with CO, C8 showed smaller particle size, lower reduction temperature and larger BET and Cu surface areas.

An Efficient Solid-State Synthesis of N-Aryl-2-phenyldiazenecarboxamides

A new and ancient solid-state reaction using K3Fe(CN)(6)/KOII to oxidize diaryl semicarbazides for preparing azo compounds has been reported. Nine N-aryl-2-phenyl-diazenecarboxamides have been synthesized in excellent yields with simple instrument.

Bifunctionality of Cu/ZnO catalysts for alcohol-assisted low-temperature methanol synthesis from syngas:Effect of copper content

Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO;catalysts while varying the copper content（X）. Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper,which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content（X） strongly affected the catalytic activity of the Cu/ZnO;catalysts, and accordingly, the Cu/ZnO;.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.

Sustainable solid-state synthesis of uniformly distributed PdAg alloy nanoparticles for electrocatalytic hydrogen oxidation and evolution

New sustainable syntheses based on solid-state strategies have sparked enormous attention and provided novel routes for the synthesis of supported metallic alloy nanocatalysts(SMACs).Despite considerable recent progress in this field,most of the developed methods suffer from either complex operations or poorly controlled morphology,which seriously limits their practical applications.Here,we have developed a sustainable strategy for the synthesis of PdAg alloy nanoparticles(NPs)with an ultrafine size and good dispersion on various carbon matrices by directly grinding the precursors in an agate mortar at room temperature.Interestingly,no solvents or organic reagents are used in the synthesis procedure.This simple and green synthesis procedure provides alloy NPs with clean surfaces and thus an abundance of accessible active sites.Based on the combination of this property and the synergistic and alloy effects between Pd and Ag atoms,which endow the NPs with high intrinsic activity,the PdAg/C samples exhibit excellent activities as electrocatalysts for both the hydrogen oxidation and evolution reactions(HOR and HER)in a basic medium.Pd9Ag1/C showed the highest activity in the HOR with the largest j0,m value of 26.5 A g Pd^–1 and j0,s value of 0.033 mA cmPd^–2,as well as in the HER,with the lowest overpotential of 68 mV at 10 mA cm^–2.As this synthetic method can be easily adapted to other systems,the present scalable solid-state strategy may open opportunity for the general synthesis of a wide range of well-defined SMACs for diverse applications.

Low-Temperature Solid State Synthesis and Characterization of Superconducting Vanadium Nitride

Superconducting vanadium nitride （VN） is successfully synthesized by a solid-state reaction of vanadium pentox- ide, sodium amide and sulfur in an autoclave at a relatively low temperature （240-400℃）. The obtained samples are characterized by x-ray diffraction, x-ray photoelectron spectroscopy and transmission electron microscopy. The result of the magnetization of the obtained VN product as a function of temperature indicates that the onset superconducting transition temperature is about 8.4K. Furthermore, the possible reaction mechanism is also discussed.

Ba_2SbGaS_5 : Solid-state Synthesis, Crystal and Electronic Structures, and Property Characterization

Single crystal of Ba2SbGaSs has been synthesized by the high temperature solidstate reaction method. The compound crystallizes in the orthorhombic space group Pnma with a = 12.177（4）, b = 8.880（3）, c = 8.982（3） A, V= 971.4（6） A3, Z = 4, De = 4.284 g/cm3,μ = 14.487 mm-1, F（000） - 1096, the final R = 0.0171 and wR = 0.0384 for all data. The structure comprises an infinite one-dimensional 1∞[SbGaS5]4- anionic chain constructed from the GaS4 tetrahedra and the SbS5 polyhedra via sharing edge alternately. The paralleled 1∞[SbGaS5]4anionic chains engage with each other and form the two-dimensional Sb-Ga-S layer perpendicular to a-axis with the isolated Ba2＋ cations arranged between layers. The IR spectrum and the UV-Vis spectrum have been investigated. Also, the first-principles band structure and density of states calculations indicate that the compound belongs to indirect semiconductor with the band gap of 2.1 eV, which is supported by the UV-Vis diffuse reflectance results.

Carbon Nitride Nanowire Bundle and Tubes:Solid-state Synthesis,Characterization and Photoluminescent Properties

Graphite-like carbon nitride nanowire bundles were synthesized from melamine via the solid state thermolysis at relatively low temperature（400℃）.Hexagonal carbon nitride tubes were prepared for the first time by heating the nanowire bundles at 550 ℃ in argon atmosphere.The forming process of tubes and transformation of the molecular structures from s-triazine rings to tri-s-triazine units were analyzed.The blue and yellow-green emission photoluminescent（PL） properties of the products were investigated in detail,and the reasons for the differences of PL properties between the bundles and tubes were discussed.

A Green and Facile Solid-state Synthesis Method for the Preparation of Diazenecarboxamide Azo Compounds with Potassium Ferricyanide and Sodium Hydroxide System

Eleven new-typed azo compounds were synthesized in good yields by dehydrogenating the corresponding aryl substituted semicarbazides using potassium ferricyanide and sodium hydroxide system under solid-state conditions.

Low-Temperature Synthesis of ZnO Nanorods Stabilized with PVP

Small-diameter ZnO nanorods with lengths of 35-50 nm were synthesized by solvothermal treatment route at low temperature(70℃)for 48,96 and 144 hours using polyvinylpyrrolidone(PVP)as stabilizing agent.The optical band gap energy of nanorods was calculated by Tauc’s approximation,obtaining values of 3.30-3.21 eV.By X-ray diffraction(XRD)it was determined that ZnO samples crystallize in Wurtzite hexagonal structure and present changes in lattice parameters.Also XRD patterns reveal a preferential growth of ZnO nanostructures along the plane with Miller indices(002).Stabilization process of ZnO nanoparticles and nanorods was studied by Fourier-transform infrared(FT-IR)spectroscopy,determining that the presence of amide group in polymer structure confers the ability to interact electrostatically with ZnO nanostructures surface.FT-IR results revealed that O and N atoms of amide group interact strongly with the surface of ZnO nanostructures.The length/diameter ratio of ZnO nanorods at 48 and 96 hours of reflux was 2.3 and 2.7,respectively.

Solid-State Synthesis of Metastable Ytterbium (II) Oxide

Due to its electron configuration (Xe) 4 f14 6 s2, Ytterbium (Yb) could form divalent oxide, YbO. In this study, the solid-state synthesis of metastable YbO was investigated by the oxidation of Yb metal at normal pressure using two experimental conditions: 1) heat treatment of Yb metal under Ar gas atmosphere with metal carbonate as an oxygen source;and 2) heat treatment of Yb metal under the continuous gas flow condition using various gas atmospheres. Products were identified using the powder X-ray diffraction and scanning electron microscope. It was found that almost single phase YbO was obtained in the experimental condition 1) using the molar ratio of Ca-CO3/Yb = 0.4. Thermodynamic calculations suggested that the YbO formation be controlled not by thermodynamics but by kinetics, and further that the evaporation of Yb metal in the BN crucible played a key role for the formation of the meta-stable YbO.

Mechanical densification synthesis of single-crystalline Ni-rich cathode for high-energy lithium-ion batteries

The intergranular microcracking in polycrystalline Ni-rich cathode particle is led by anisotropic volume change and stress corrosion along grain boundary,accelerating battery performance decay.Herein,we have suggested a simple but advanced solid-state method that ensures both uniform transition metal distribution and single-crystalline morphology for Ni-rich cathode synthesis without sophisticated coprecipitation.Pelletization-assisted mechanical densification(PAMD)process on solid-state precursor mixture enables the dynamic mass transfer through the increased solid-solid contact area which facilitates the grain growth during sintering process,readily forming micro-sized single-crystalline particle.Furthermore,the improved chemical reactivity by a combination of capillary effect and vacancyassisted diffusion provides homogeneous element distribution within each primary particle.As a result,single-crystalline Ni-rich cathode with PAMD process has eliminated a potential evolution of intergranular cracking,thus achieving superior energy retention capability of 85%over 150 cycles compared to polycrystalline Ni-rich particle even after high-pressure calendering process(corresponding to electrode density of~3.6 g cm^(-3))and high cut-off voltage cycling.This work provides a concrete perspective on developing facile synthetic route of micron-sized single-crystalline Ni-rich cathode materials for high energy density lithium-ion batteries(LIBs).

A systematic approach for synthesizing a low-temperature distillation system

In this paper, by combining a stochastic optimization method with a refrigeration shaft work targeting method,an approach for the synthesis of a heat integrated complex distillation system in a low-temperature process is presented. The synthesis problem is formulated as a mixed-integer nonlinear programming(MINLP) problem,which is solved by simulated annealing algorithm under a random procedure to explore the optimal operating parameters and the distillation sequence structure. The shaft work targeting method is used to evaluate the minimum energy cost of the corresponding separation system during the optimization without any need for a detailed design for the heat exchanger network(HEN) and the refrigeration system(RS). The method presented in the paper can dramatically reduce the scale and complexity of the problem. A case study of ethylene cold-end separation is used to illustrate the application of the approach. Compared with the original industrial scheme, the result is encouraging.

SYNTHESIS AND PROPERTIES OF HIGH MOLECULAR WEIGHT POLY(LACTIC ACID) AND ITS RESULTANT FIBERS

Direct melt/solid polycondensation of lactic acid(LA)was carried out to obtain high molecular weight poly(lactic acid)(PLA)by a process using various catalysts in the first-step melt polycondensation,and followed solid polycondensation by using p-toulenesulfonic acid monohydrate(TSA)as the catalyst in the second step.Effects of various catalysts and reaction temperature on the molecular weight and crystallinity of resulting PLA polymers were examined.It was shown that SnCl_2·2H_2O/TSA,SnCl_2·2H_2O/succinic ...

Preliminary Synthesis and Characterization of Mesoporous Nanocrystalline Zirconia

A novel method to prepare mesoporous nano-zirconia was developed. Thesynthesis was carried out in the presence of PEO surfactants via a solid-state reaction. Thematerials exhibit a strong diffraction peak at low 2θ angle and their nitrogenadsorption/desorption isotherms are typical of type IV with H1 hysteresis loops. The pore structureimaged by TEM can be described as wormhole domains. The tetragonal zirconia nanocrystals are uniformin size (around 1.5 nm) and their mesopores focus on around 4.6 nm. The zirconia nanocrystal growthis tentatively postulated to be the result of an aggregation mechanism. This study also revealsthat the PEO surfactants can interact with the Zr-O-Zr framework to reinforce the thermal stabilityof zirconia. The ratio of NaOH to ZrOCl_2, crystallization and calcination temperature play animportant role in the synthesis of mesoporous nano-zirconia.

Mechanochemical redox-based synthesis of highly porous CoxMn1-xOy catalysts for total oxidation

A mechanochemical redox reaction between KMnO4 and CoCl2 was developed to obtain a CoxMn1-xOy catalyst with a specific surface area of 479 m^2 g^-1,which was higher than that obtained using a co-precipitation(CP)method(34 m2 g^-1),sol-gel(SG)method(72 m^2 g^-1),or solution redox process(131 m^2 g^-1).During catalytic combustion,this CoxMn1-xOy catalyst exhibited better activity(T100 for propylene=~200℃)than the control catalysts obtained using the SG(325℃)or CP(450℃)methods.The mechanical action,mainly in the form of kinetic energy and frictional heating,may generate a high degree of interstitial porosity,while the redox reaction could contribute to good dispersion of cobalt and manganese species.Moreover,the as-prepared CoxMn1-xOy catalyst worked well in the presence of water vapor(H2O 4.2%,>60 h)or SO2(100 ppm)and at high temperature(400℃,>60 h).The structure MnO2·(CoOOH)2.93 was suggested for the current CoxMn1-xOy catalyst.This catalyst could be extended to the total oxidation of other typical hydrocarbons(T90=150°C for ethanol,T90=225°C for acetone,T90=250℃for toluene,T90=120℃for CO,and T90=540℃for CH4).Scale-up of the synthesis of CoxMn1-xOy catalyst(1 kg)can be achieved via ball milling,which may provide a potential strategy for real world catalysis.

A Novel Synthesis of Polyaniline Doped with Heteropolyacid and its Special Property

Polyaniline doped with heteropolyacid was synthesized using solid-state synthesis method. XRD pattern showed that polyaniline molecule has highly ordered arrangement. Fluorescence property of the polyaniline materials was found.