Transformation of Undesired Li_(2)CO_(3)into Lithiophilic Layer Via Double Replacement Reaction for Garnet Electrolyte Engineering

Garnet-type solid-state electrolytes(SSEs)are a remarkable Li-ion electrolyte for the realization of next-generation all-solid-state lithium batteries due to their excellent stability against Li metal as well as high ionic conductivities at room temperature.However,garnet electrolytes always contain undesired and hardly removable Li_(2)CO_(3) contaminations that have persistently large resistance and unstable interface contact with Li metal.This is a critical bottleneck for the practical application of garnet electrolytes.Here,we design a novel strategy to completely root out Li_(2)CO_(3) both inside and on the surface of garnet.This is achieved by a so-called double replacement reaction between Li_(2)CO_(3) and SiO_(2) during one-step hot press process for garnet electrolyte densification.It leads to in-situ transformation of LixSiOy(LSO)mostly locating around the grain boundaries of garnet.Due to the higher ion conductivity and better electrochemistry stability of LSO than Li_(2)CO_(3),the modified garnet electrolyte shows much improved electrochemical performance.Moreover,the wettability between modified garnet electrolyte and lithium metals was significantly enhanced in the absence of surface Li_(2)CO_(3).As a proof of concept,an assembled Li symmetric cell with modified garnet electrolyte displays a high critical current density(CCD)of 0.7 mA cm^(-2)and a low interfacial impedance(5Ωcm^(2))at 25℃.These results indicate that the upcycling of Li_(2)CO_(3)is a promising strategy to well-address the degradation and interfacial issue associated with garnet electrolytes.

Laser Double Ablation Reactions of Chromium(Iron)and Sulfur Clusters

The sulfides of transitional metals chromium[1-3] and iron[4] are of great importance inmaterial and biology sciences due to their characteristic structures and properties．So the studyon the properties of Cr－S and Fe－S clusters will give many contributions to the understandingof physical and chemical behavior of those compounds．

Mixed convection effects on heat and mass transfer in a non Newtonian fluid with chemical reaction over a vertical plate

This paper studies mixed convection,double dispersion and chemical reaction effects on heat and mass transfer in a non-Darcy non-Newtonian fluid over a vertical surface in a porous medium under the constant temperature and concentration.The governing boundary layer equations,namely,momentum,energy and concentration,are converted to ordinary differential equations by introducing similarity variables and then are solved numerically by means of fourth-order Runge-Kutta method coupled with double-shooting technique.The velocity,temperature concentration,heat and mass transfer profiles are presented graphically for various values of the parameters,and the influence of viscosity index n,thermal and solute dispersion,chemical reaction parameter χ are observed.

Synthesis of Mg-Al-carbonate layered double hydroxide by an atom-economic reaction

A clean method for preparing layered double hydroxides （LDHs） has been developed, featured by using the hydroxides of two different metals as starting materials by atom-economic reactions. The reactions were carried out under hydrothermal conditions in either a high pressure autoclave or a microwave digester. The compositions, structural parameters and thermal behavior of the resulting LDHs are very similar to those of materials produced by using the separate nucleation and aging steps （SNAS） method. The major advantage of the new method is that no by-product is produced, so that filtration and washing processes are unnecessary. The consequent reduction in water consumption is beneficial to the environment.

Functional Ionic Liquids Promoted Double Michael Reaction of Benzofuran-3-one or 1-1ndone and Symmetric Dienones： Construction of Spiro[benzofuran-2,1′-cyclohexane]-3-one or Spiro[cyclohexane-1,2′-indene]-1′,4（3′H）-dione Derivatives

The double Michael reactions between benzofuran-3-one or 1-indone and symmetric dienones in the presence of catalytic ionic liquids were successfully developed and spiro[benzofuran-2, 1′-cyclohexane]-3-one or spiro[cyclo- hexane-1,2′-indene]-1′,4（3′H）-dione derivatives containing a spiro quaternary stereogenic center, which widely exist in biologically active products and building blocks in organic synthesis, were obtained in excellent yields （up to 99%）. This catalytic system was also extended to the double Michael reaction of less reactive 1-indone and the desired products were also obtained in 31%-62% yields. The catalytic system was highly active and efficient for a broad of substrates under mild conditions.

Organocatalytic Asymmetric Double Michael Reaction of Benzofuranone with Dienones to Construct Spirocyclic Benzofuranones

The enantioselective double Michael reaction of benzofuranone with dienones catalyzed by Cinchona-based primary amines was developed. A number of optically active spirocyclic benzofuranones were obtained in up to 89% yield and 91% ee.

Phosphorus oxoanion-intercalated layered double hydroxides for high-performance oxygen evolution

Rational design and controlled fabrication of efficient and cost-effective electrodes for the oxygen evolution reaction （OER） are critical for addressing the unpre- cedented energy crisis. Nickel-iron layered double hydroxides （NiFe-LDHs） with specific interlayer anions （i.e. phosphate, phosphite, and hypophosphite） were fabricated by a co-predpitation method and investigated as oxygen evolution electrocatalysts. Intercalation of the phosphorus oxoanion enhanced the OER activity in an alkaline solution; the optimal performance （i.e., a low onset potential of 215 mV, a small Tafel slope of 37.7 mV/dec, and stable electrochemical behavior） was achieved with the hypophosphite-intercalated NiFe-LDH catalyst, demonstrating dramatic enhancement over the traditional carbonate-intercalated NiFe-LDH in terms of activity and durability. This enhanced performance is attributed to the interaction between the intercalated phosphorous oxoanions and the edge-sharing MO6 （M = Ni, Fe） layers, which modifies the surface electronic structure of the Ni sites. This concept should be inspiring for the design of more effective LDH-based oxygen evolution electrocatalvsts.

A highly active oxygen evolution electrocatalyst： Ultrathin CoNi double hydroxide/CoO nanosheets synthesized via interface-directed assembly

A cost-efficient and stable oxygen evolution electrocatalyst is essential for improving energy storage and conversion efficiencies. Herein, 2D nanosheets with randomly cross-linked CoNi layered double hydroxide （LDH） and small CoO nanocrystals were designed and synthesized via in situ reduction and interface- directed assembly in air. The formation of CoNi LDH/CoO nanosheets was attributed to the strong extrusion of hydrated metal-oxide clusters driven by the interfacial tension. The obtained loose and porous nanosheets exhibited low crystallinity due to the presence of numerous defects. Owing to the orbital hybridization between metal 3d and O 2p orbitals, and electron transfer between metal atoms through Ni-O-Co, a number of Co and Ni atoms in the CoNi LDH present a high ＋3 valency. These unique characteristics result in a high density of oxygen evolution reaction （OER） active sites, improving the affinity between OH- and catalyst, and resulting in a large accessible surface area and permeable channels for ion adsorption and transport. Therefore, the resulting nanosheets exhibited high catalytic activity towards the OER. The CoNi LDH/CoO featured a low onset potential of 1.48 V in alkaline medium, and required an overpotential of only 300 mV at a current density of 10 mA.cm-2, while displaying good stability in accelerated durability tests.

Effects of redox-active interlayer anions on the oxygen evolution reactivity of NiFe-layered double hydroxide nanosheets

Nickel-iron layered double hydroxide （NiFe-LDH） nanosheets have shown optimal oxygen evolution reaction （OER） performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential （high reducing ability）, such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential （low reducing ability）, such as fluorion, show a high overpotential of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. This increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.

Dehydrated layered double hydroxides： Alcohothermal synthesis and oxygen evolution activity

Layered double hydroxides （LDHs） are a materials with extensive applications and class of two-dimensional （2D） layered well-developed synthesizing methods in aqueous media. In this work, we introduce an alcohothermal synthesis method for fabricating NiFe-LDHs with dehydrated galleries. The proposed process involves incomplete hydrolysis of urea for the simultaneous precipitation of metal ions, with the resulting water-deficient ethanol environment leading to the formation of a dehydrated structure. The formation of a gallery-dehydrated layer structure was confirmed by X-ray diffraction （XRD）, as well as by a subsequent rehydration process. The methodology introduced here is also applicable for fabricating Fe-based LDHs （NiFe-LDH and NiCoFe-LDH） nanoarrays, which cannot be produced under the same conditions in aqueous media because of the different precipitation processes involved. The LDH nanoarrays exhibit excellent electrocatalytic performance in the oxygen evolution reaction, as a result of their high intrinsic activity and unique structural features. In summary, this study not only introduces a new method for synthesizing LDH materials, but also provides a new route towards highly active and robust electrodes for electrocatalvsis.

Double Nucleophilic Addition of Ketene Silyl (THIO)Acetals and Trimethylsilyl Cyanide to N-Allylideneamine

1 Results We have already published a double nucleophilic addition reaction of α,β-unsaturated imines with several nucleophiles such as ketene silyl acetals, trimethylsilyl cyanides, trimethylsilyl azides and thiols[1]. However, it was not easy to use N-allylideneamine 2 derived from acrolein for such reactions. Since there is no substituent at the β-position, imine 2 has high reactivity and are prone to be polymerization. We report the first synthesis of N-allylideneamines 2 using the isomerization of ...

Microwave-assisted,facile,rapid and solvent-free one pot two-component synthesis of some special acylals

A facile, rapid and solvent-flee method for the conversion of acids and dihalomethane to the corresponding methylene diesters （acylals） using microwave as activators or assistor, is reported. This method is particularly powerful for the diesterification of carboxylic acids, which afford methylene diesters in good to excellent yields （up to 〉99%）. When the intermediate is trapped, a ＂double successive SN2 reactions＂ mechanism is proved.

One-step synthesis of some polyfluoroalkylated 1,3-benzodioxoles, 4H-l,3-benzodioxins anddibenzo[d,f] [l,3]dioxepins

Several polyfluoroalkylated heterocyclic compounds containing methylenedioxy group such as 2-(F-alkyl) substituted 1,3-benzodioxole, piperonal, 4H-1,3-benzodioxin, 1,3-dioxolane and 6-(F-alkyl) substituted dibenzo[d,f][1,3]dioxepin have been prepared through double Michael-addition reactions of 2,2-dihydropolyfluoroalkanoates with the corresponding diphenols or diols in high yields.