Design of ZnSe-CoSe heterostructure decorated in hollow N-doped carbon nanocage with generous adsorption and catalysis sites for the reversibly fast kinetics of polysulfide conversion

Although lithium-sulfur batteries(Li SBs)are regarded as one of the most promising candidates for the next-generation energy storage system,the actual industrial application is hindered by the sluggish solid–liquid phase conversion kinetics,severe shuttle effect,and low sulfur loadings.Herein,a zeolitic imidazolate framework(ZIF)derived heterogeneous ZnSe-CoSe nanoparticles encapsulated in hollow N-doped carbon nanocage(ZnSe-CoSe-HNC)was designed by etching with tannic acid as a multifunctional electrocatalyst to boost the polysulfide conversion kinetics in LiSBs.The hollow structure in ZIF ensures large inner voids for sulfur and buffering volume expansions.Abundant exposed ZnSe-CoSe heterogeneous interfaces serve as bifunctional adsorption-catalytic centers to accelerate the conversion kinetics and alleviate the shuttle effect.Together with the highly conductive framework,the ZnSe-CoSeHNC/S cathode exhibits a high initial reversible capacity of 1305.3 m A h g-1at 0.2 C,high-rate capability,and reliable cycling stability under high sulfur loading and lean electrolyte(maintaining at 745 m A h g-1after 200 cycles with a high sulfur loading of 6.4 mg cm-2and a low electrolyte/sulfur ratio of 6μL mg^(-1)).Theoretical calculations have demonstrated the heterostructures of ZnSe-CoSe offer higher binding energy to lithium polysulfides than that of ZnSe or CoSe,facilitating the electron transfer to lithium polysulfides.This work provides a novel heterostructure with superior catalytic ability and hollow conductive architecture,paving the way for the practical application of functional sulfur electrodes.

Conversion of Kinetic Energy from Synoptic Scale Disturbance to Low-Frequency Fluctuation over the Yangtze River Valley in the Summers of 1997 and 1999

In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic energy is derived. The energy conversion is then calculated and analyzed for the summers of 1997 and 1999. The results show that the energy conversion from the SSD to the LFF is obviously enhanced in the middle and lower troposphere during the heavy rainfall, suggesting this to be one of mechanisms inducing the heavy rainfall, although the local LFF kinetic energy may not be enhanced.

Impact of Two-Way FDI on the Industrial Structure in Shandong Province Under the Background of “New and Old Kinetic Energy Conversion”

This paper uses the panel data of 17 cities in Shandong Province from 2003 to 2018 to construct a panel model to empirically study the impact of foreign direct investment(FDI)on the industrial structure.The results show that two-way investment,financial industry development,and policy variables have significant roles in promoting the advancement of the industrial structure in the province.In the future implementation of the“Going Global”strategy in Shandong Province,the cooperation between two-way investment and the financial industry should be strengthened,the level of regional financial development should be improved,and the impact of two-way investment on the optimization and upgrading of the industrial structure should be reinforced.

Oxygen-deficient titanium dioxide supported cobalt nano-dots as efficient cathode material for lithium-sulfur batteries

Lithium sulfur(Li-S)batteries demonstrate great promise for efficient energy storage systems once the lithium polysulfide(LPS)shuttling and sluggish redox kinetics can be well addressed.Herein,we developed a sea urchin-structured oxygen-deficient titanium dioxide semiconductor anchored with cobalt nano-dots(Co@TiO2-x)as a high-performance multifunctional sulfur host material for Li-S batteries.The sea urchin-structured Co@TiO2-x offers strong structural stability and strengthened chemical interaction towards LPS.Meanwhile,the incorporation of Co nano-dots into TiO2 leads to increased oxygen vacancies,which augments the electrical conduction and benefits LPS conversion acceleration as well.As a result,the oxygen vacancy-rich Co@TiO2-x composite exhibits excellent conductivity,strong LPS confinement and promoted sulfur electrochemical kinetics,rendering enhanced LPS shuttling inhibition and rapid redox reaction.Attributed to these features,the Co@TiO2-x/S cathode exhibits a discharge capacity of 803 mAh g-1at 1 C and a good cyclic stability upon 500 cycles with a low capacity fading rate of 0.07%per cycle.This synergistic design of conductive multifunctional LPS barrier is also promising to enlighten the material engineering in other energy storage applications.

Research on the Necessity of Building National-level Grape and Cherry Germplasm Resources Bank in Shandong Province

At present,the grape and cherry industries in Shandong are in the leading position in China and have driven the development of related high-end manufacturing industries such as wine,brandy,preserved fruit processing,fruit juice processing and health products. Therefore,vigorously developing the grape and cherry industries in Shandong Province and carrying out development and innovation are important parts of Shandong Province in responding to the strategy of national new and old kinetic energy conversion. However,currently the germplasm resources preserved in the fruit tree resources banks in China are only 45% of those in the US and 27. 2% of those in the EU. Moreover,the development of fruit trees resources banks in Shandong is relatively backward in China,and there is still no banks related with grape and cherry germplasm resources in Shandong. Therefore,importance can be attached to the agriculture,forestry,and animal husbandry to build germplasm resources banks for grape and cherry industries in Shandong Province. Building the national-level grape and cherry germplasm resources bank in Shandong Province can also promote the utilization of wild and farm germplasm resources in the future; advance the research on the genes related to disease resistance,stress resistance and quality of grapes and cherries; push forward the construction and development of cherry and grape mutants banks. It is conducive to the research on the agronomic traits of grapes and cherries,and can provide the parents resources for planting innovation and improving the quality of grapes and cherries,as well as promote the development and application of molecular markers of grapes and cherries,including the identification of lines and crossbreeding. Thereby,it cannot only promote the industry development,but also achieve the development of cultivation,breeding and basic research in an all-round way and the development of ＂ production,study and research＂ going side by side.

Terminal sulfur atoms formation via defect engineering strategy to promote the conversion of lithium polysulfides

The defect engineering shows great potential in boosting the conversion of lithium polysulfides intermediates for high energy density lithium-sulfur batteries(LSBs),yet the catalytic mechanisms remain unclear.Herein,the oxygen-defective Li_(4)Ti_(5)O_(12)-xhollow microspheres uniformly encapsulated by N-doped carbon layer(OD-LTO@NC)is delicately designed as an intrinsically polar inorganic sulfur host for the research on the catalytic mechanism.Theoretical simulations have demonstrated that the existence of oxygen deficiencies enhances the adsorption capability of spinel Li_(4)Ti_(5)O_(12)towards soluble lithium polysulfides.Some-S-S-bonds of the Li2S6on the defective Li_(4)Ti_(5)O_(12)surface are fractured by the strong adsorption force,which allows the inert bridging sulfur atoms to be converted into the susceptible terminal sulfur atoms,and reduces the activation energy of the polysulfide conversion in some degree.In addition,with the N-doped carbon layer,secondary hollow microspheres architecture built with primary ultrathin nanosheets provide a large amount of void space and active sites for sulfur storage,adsorption and conversion.The as-designed sulfur host exhibits a remarkable rate capability of 547 m Ah g^(-1)at 4C(1 C=1675 m A g^(-1))and an outstanding long-term cyclability(519 m Ah g^(-1)after 1000 cycles at 3 C).Besides,a high specific capacity of 832 m Ah g^(-1)is delivered even after 100 cycles under a high sulfur mass loading of 3.2 mg cm^(-2),indicating its superior electrochemical performances.This work not only provides a strong proof for the application of oxygen defect in the adsorption and catalytic conversion of lithium polysulfides,but offers a promising avenue to achieve high performance LSBs with the material design concept of incorporating oxygen-deficient spinel structure with hierarchical hollow frameworks.

Selenium vacancies enable efficient immobilization and bidirectional conversion acceleration of lithium polysulfides for advanced Li-S batteries

Heterostructures composed of oxides and sulfides(nitrides or carbides)show great potential as sulfur host additives because of the strong adoptability of oxides and catalytic capability of sulfides towards the notorious lithium polysulfides(LiPSs).However,the migration and conversion pathway of LiPSs is seriously confined at a localized interface with inadequate active sites.In this work,the introduction of selenium vacancies into VSe_(2−x)has been demonstrated to successfully synergize the adsorbability and catalytic reactions of LiPSs at an integrated functional surface.The N-doped carbon nanosheets-assembled flower architectures embedded with selenium vacancy-rich VSe_(2−x)and partial vanadium oxides have been controllably synthesized and employed as the cathode additives for lithium-sulfur(Li-S)batteries.Both the experiments and first-principle calculations reveal their strong adsorption to LiPSs and their bidirectional catalytic functionality towards the conversion between S8 and Li_(2)S.As expected,the charge and discharge kinetics of VSe_(2−x)containing sulfur cathodes is fundamentally improved(an outstanding rate capabilitiy with 693.7 mAh·g^(−1)at 2 C,a remarkable long-term cyclability within 1,000 cycles at 2 C with S loading 2.27 mg·cm^(−2),and an excellent areal capacity with 3.44 mAh·cm^(−2)within 100 cycles at 0.5 C).This work presents an effective resolution to couple the adsorbability and catalytic reactions of LiPSs at the material design perspective,and the insights on bidirectional catalytic functionality are of vital to develop functional materials for advanced Li-S batteries.

The use of a ternary metal sulfide loading on carbon fibers as the sulfur host for high performance low-temperature lithium sulfur batteries

The use of lithium-sulfur(Li-S)batteries is limited by sulfur redox reactions involving multi-phase transformations,especially at low-temperatures.To address this issue,we report a material(FCNS@NCFs)consisting of nitrogen-doped carbon fibers loaded with a ternary metal sulf-ide((Fe,Co,Ni)_(9)S_(8))for use as the sulfur host in Li-S batteries.This materi-al was prepared using transfer blot filter paper as the carbon precursor,thiourea as the source of nitrogen and sulfur,and FeCl_(3)·6H_(2)O,CoCl_(2)·6H_(2)O and NiCl_(2)·6H_(2)O as the metal ion sources.It was synthesized by an impreg-nation method followed by calcination.The nitrogen doping significantly in-creased the conductivity of the host,and the metal sulfides have excellent catalytic activities.Theoretical calculations,and adsorption and deposition experiments show that active sites on the surface of FCNS@NCFs selectively adsorb polysulfides,facilitate rapid adsorption and conversion,prevent cathode passivation and inhib-it the polysulfide shuttling.The FCNS@NCFs used as the sulfur host has excellent electrochemical properties.Its initial dis-charge capacity is 1639.0 mAh g^(−1) at 0.2 C and room temperature,and it remains a capacity of 1255.1 mAh g^(−1) after 100 cycles.At−20~C,it has an initial discharge capacity of 1578.5 mAh g^(−1) at 0.2 C,with a capacity of 867.5 mAh g^(−1) after 100 cycles.Its excellent performance at both ambient and low temperatures suggests a new way to produce high-performance low-temper-ature Li-S batteries.

STUDY ON KINETIC ENERGY BUDGET OF A TYPHOON——THE CONVERSION BETWEEN KINETIC ENERGIES OF DIVERGENT WINDS AND NON-DIVERGENT WINDS

This paper is the Part Ⅱ of studying the budget of kinetic energy of the typhoon No. 7507, with the emphasis on the conversion between the kinetic energy of the divergent winds and that of the non-divergent winds, and its relationship to the heating field. The main findings have been brought out as follows.

Synthesis,characterization,and photocatalytic activity of porous La–N–co-doped TiO_2 nanotubes for gaseous chlorobenzene oxidation

The photocatalytic oxidation of gaseous chlorobenzene（CB） by the 365 nm-induced photocatalyst La/N–Ti O2, synthesized via a sol–gel and hydrothermal method, was evaluated. Response surface methodology（RSM） was used to model and optimize the conditions for synthesis of the photocatalyst. The optimal photocatalyst was 1.2La/0.5N–Ti O2（0.5） and the effects of La/N on crystalline structure, particle morphology, surface element content, and other structural characteristics were investigated by XRD（X-ray diffraction）, TEM（Transmission Electron Microscopy）, FTIR（Fourier transform infrared spectroscopy）, UV–vis（Ultraviolet–visible spectroscopy）, and BET（Brunauer Emmett Teller）. Greater surface area and smaller particle size were produced with the co-doped Ti O2 nanotubes than with reference Ti O2. The removal of CB was effective when performed using the synthesized photocatalyst,though it was less efficient at higher initial CB concentrations. Various modified Langmuir-Hinshelwood kinetic models involving the adsorption of chlorobenzene and water on different active sites were evaluated. Fitting results suggested that competitive adsorption caused by water molecules could not be neglected, especially for environments with high relative humidity. The reaction intermediates found after GC–MS（Gas chromatography–mass spectrometry） analysis indicated that most were soluble, low-toxicity, or both. The results demonstrated that the prepared photocatalyst had high activity for VOC（volatile organic compounds） conversion and may be used as a pretreatment prior to biopurification.

FEATURES OF VARIATION IN TOTAL,BAROTROPIC AND BAROCLINIC KINETIC ENERGY WITH THE MECHANISM EXPLORED AROUND THE 1998 SCS SUMMER MONSOON ONSET

This paper concerns atmospheric kinetic energy variation related to the onset of summer monsoon in May,1998 over the SCS (South China Sea).Results show that around the onset, noticeable conversion occurs in atmospheric total,barotropic and baroclinic kinetic energy (KE) at 300-1000 hPa;three days before the onset,total and barotropic KE are already growing markedly and baroclinic KE increases simultaneously with the onset:the monsoon's onset is associated closely to the meridional propagation of barotropic and baroclinic KE in the SCS region and study of equations of barotropie/baroclinic KE indicates that the net production term is the dominant factor for the change of the two forms of KE,the term of fluxes plays a part in weakening the energies and the conversion term is responsible for transforming barotropic into baroclinic KE.