MXene is a rising star of two-dimensional(2D)materials for energy relative applications,however,the traditional synthesis of MXene etched by hazard HF acid or LiF+HCl mixed solution is highly dangerous with the risk o...MXene is a rising star of two-dimensional(2D)materials for energy relative applications,however,the traditional synthesis of MXene etched by hazard HF acid or LiF+HCl mixed solution is highly dangerous with the risk of splashing or pouring liquid solutions.In this work,we developed a water-free ionothermal synthesis of 2D Ti3C2 MXene via etching pristine Ti3AlC2 MAX in low-cost choline chloride and oxalic acid based deep eutectic solvents(DES)with the presence of NH4F,thus it was highly safe and convenient to operate solid precursor and product materials at room temperature.Benefited from the low vapor pressure and solvating properties of DES,the prepared Ti3C2(denoted as DES-Ti3C2)possessed a high purity up to 98% compared with 95% for HF etched Ti3C2(denoted as HF-Ti3C2).Notably,an expanded interlayer spacing of 1.35 nm could be achieved due to the intercalation of choline cations in DES-Ti3C2,larger than that of HF-Ti3C2(0.98 nm).As a result,the DES-Ti3C2 anodes exhibited enhanced lithium storage performance,such as high reversible capacity of 208 m Ah g-1at 0.5 A g-1,and long cycle life over 400 times,outperforming most reported pure MXene anodes.The ionothermal synthesis of MXene developed here may pave a new way to safely prepare other MXene for various energy relating applications.展开更多
Fenlong Technology has been applied to increase yield by 20%-50%,improve quality by 5%,and retain water by 100%in 40 kinds of crop cultivated land and saline-alkali land in 26 provinces of China.This paper clarified f...Fenlong Technology has been applied to increase yield by 20%-50%,improve quality by 5%,and retain water by 100%in 40 kinds of crop cultivated land and saline-alkali land in 26 provinces of China.This paper clarified for the first time the scientific theory system of Fenlong Technology using three-dimensional space resources"Fenlong Agricultural Nature Theory"and the development of the relative"limits"of agricultural growth,which provides a huge power support and natural force for expanding human living spaces.Through inventing and creating a scientific and technological system of farming tools,farming machinery,farming modes,and magic weapons for cultivation,Fenlong Technology can increase grain,promote ecological development,and greatly expand the living spaces of the Chinese nation and achieve sustainable development.Using Fenlong Technology,China has expanded from the current single"cultivated land agriculture"to the"big pattern agriculture"of Fenlong"cultivated land+saline land+degraded grassland+marginal land+desertified land+river water",flexibly used 147 million ha of"three-dimensional space resources"of land,and the newly increased food,meat,and fish can feed 300 million to 400 million people,increased the water storage by 100 billion m^(3),and reduced the collection of groundwater by 20 million to 60 billion m^(3).展开更多
Two-dimensional(2D)MoS_(2) nanomaterials have been extensively studied due to their special structure and high theoretical capacity,but it is still a huge challenge to improve its cycle stability and achieve superior ...Two-dimensional(2D)MoS_(2) nanomaterials have been extensively studied due to their special structure and high theoretical capacity,but it is still a huge challenge to improve its cycle stability and achieve superior fast charge and discharge performance.Herein,a facile one-step hydrothermal method is proposed to synthetize an ordered and self-assembled MoS_(2) nanoflower(MoS_(2)/C NF)with expanded interlayer spacing via embedding a carbon layer into the interlayer.The carbon layer in the MoS_(2) interlayer can speed the transfer of electrons,while the nanoflower structure promotes the ions transport and improves the structural stability during the charging/discharging process.Therefore,MoS_(2)/C NF electrode exhibits exceptional rate performance(318.2 and 302.3 mA·h·g^(-1) at 5.0 and 10.0 A·g^(-1),respectively)and extraordinary cycle durability(98.8%retention after 300 cycles at a current density of 1.0 A·g^(-1)).This work provides a simple and feasible method for constructing high-performance anode composites for sodium ion batteries with excellent cycle durability and fast charge/discharge ability.展开更多
We study in this paper a Hilbert space HV associated with the coarse geometry of an infinite connected graph X(V, E) with vertex set V and edge set E. We show that X(V,E) is uniformly expanding if and only ifl2(V)can ...We study in this paper a Hilbert space HV associated with the coarse geometry of an infinite connected graph X(V, E) with vertex set V and edge set E. We show that X(V,E) is uniformly expanding if and only ifl2(V)can be continuously included in HV as a closed subspace,and that the inner product structure of HV is topologically invariant under uniform coarsening of the graph. We also discuss the functorial properties of these Hilbert spaces.展开更多
Earth was broken for the ZTE R&D Building at theheadquarters on October 28, 2003. Hou Weigui,President of ZTE, delivered a speech on the cere-mony. He said:“As part of the development strate-gy of ZTE, the new bu...Earth was broken for the ZTE R&D Building at theheadquarters on October 28, 2003. Hou Weigui,President of ZTE, delivered a speech on the cere-mony. He said:“As part of the development strate-gy of ZTE, the new building will play an importantrole in improving the overall R&D arrangement andthe environment of production and R&D, reducingthe operating cost and enhancing the image of thewhole company.”The R&D building will be the Shenzhen R&D展开更多
Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmann...Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs).We assume that each agent suffers from by the mixed constraints on its velocity,control input and Euler angle.Solving the MDFT problem implies that 1)The virtual state of each USV is determined in the earth coordinate by expanding its 2D work space to the 3D space.展开更多
Phase engineering has proven to be an effective strategy for achieving superior thermoelectric performance,while pressure is an excellent means of expanding the phase space of a material.In this paper,the effect of pr...Phase engineering has proven to be an effective strategy for achieving superior thermoelectric performance,while pressure is an excellent means of expanding the phase space of a material.In this paper,the effect of pressure-induced phase transition on improving the crystal symmetry and enhancing the thermoelectric properties of AgCrSe2 under high pressure and high temperature are reported.A structural phase transition from the low-symmetry R3m phase to the high-symmetry P3m1 phase is discovered below 1 GPa,which increases band degeneracy and contributes to a high electrical conductivity.For the metallic P3m1 phase,the electrons surrounding the Se2−anion gradually transfer to the Ag+and Cr3+cations as the pressure increases,decreasing the density of states around the Fermi level and thus optimizing the carrier concentration,thereby increasing the Seebeck coefficient while maintaining a high electrical conductivity.Consequently,an ultrahigh power factor of 864μW⋅m−1⋅K−2 is achieved at 5 GPa and 297 K.This study provides new insights into improving thermoelectric transport properties by applying physical pressure to enhance crystal symmetry and optimize thermoelectric parameters,and also indicates that phase engineering is a compelling strategy to discover or design novel high-performance thermoelectric materials starting from low-symmetry compounds.展开更多
0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly ...0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly prominent.China has implemented and completed several largescale land infilling and excavation projects(Figure 1),which have become the main way to increase land resources and expand construction land.展开更多
Aqueous magnesium ion supercapacitors(MISs)have attracted attention due to their safety,low cost and environmental friendliness.However,the cycling stability of MISs is usually not ideal due to magnesium ion plating i...Aqueous magnesium ion supercapacitors(MISs)have attracted attention due to their safety,low cost and environmental friendliness.However,the cycling stability of MISs is usually not ideal due to magnesium ion plating in/stripping from the negative electrode materials.Here,we demonstrate that MoS_(2)with expanded interlayer spacing(E-MoS_(2)),obtained via a facile method,is a prospective negative electrode material for rechargeable MISs,because the expanded layer spacing reduces ion diffusion resistance and provides more active sites for ion interaction.展开更多
Layered MoS_(2)has been recognized as a promising low-cost alternative to Pt-based electrocatalysts towards the hydrogen evolution reaction(HER).Intensive interest has been mainly focused on designing MoS_(2)nanostruc...Layered MoS_(2)has been recognized as a promising low-cost alternative to Pt-based electrocatalysts towards the hydrogen evolution reaction(HER).Intensive interest has been mainly focused on designing MoS_(2)nanostructures with large amounts of active edge sites and fast charge transfer.Here we report the synthesis of vanadium and nitrogen co-doped MoS_(2)on reduced graphene oxide with new defect sites on the basal/edge planes and expanded interlayer spacing.展开更多
Layered structure MoS_(2) nanosheets have shown great potential for energy storage applications.However,the methodology for elaborately controllable growth of MoS_(2) onto carbonaceous matrix for promoting the electro...Layered structure MoS_(2) nanosheets have shown great potential for energy storage applications.However,the methodology for elaborately controllable growth of MoS_(2) onto carbonaceous matrix for promoting the electrochemical performance is highly desirable.Herein,a high-effective,all-in-one in-situ conversion growth strategy has been proposed to construct a stable sandwich-type nanostructure.The formation of the optimized C-MoS_(2)/NCNTs product undergoes a dissolution-recrystallization process,in which ultra-thin carbon layer-coated MoS_(2) nanosheets densely assembled onto the surface of polyimide(PI)derived N-doped carbon nanotubes(CNTs).Theoretical simulation reveals that MoS_(2) nanosheets possessing an expanded interlayer spacing of 0.92 nm can greatly reduce the barrier energy of Na ions mitigation.Ac-cordingly,the as-made C-MoS_(2)/NCNTs anode delivers superior cycling stability(82%capacity retention after 400 cycles at 1 A g^(−1))and rate performance(348 mAh g^(−1) at 2 A g^(−1)).The results demonstrate that the expanded MoS_(2) interlayer distance,ultrathin outer carbon coating,and N-doped CNTs matrix together accounts for the outstanding sodium storage capability for the C-MoS_(2)/NCNTs electrode.展开更多
We use experimental data from Distant Type 1a Supernovae to calculate the Observed Magnitude (m - M) which is the Apparent Magnitude (m) minus the Absolute Magnitude (M) for different values of the Redshift ...We use experimental data from Distant Type 1a Supernovae to calculate the Observed Magnitude (m - M) which is the Apparent Magnitude (m) minus the Absolute Magnitude (M) for different values of the Redshift z which gives us the Distance Modulus. Then, we calculate the average velocity and average acceleration for different z values and plot them as a function of time. The expansion of the space of our 3-D Universe is exponential and it will end with a Big Bang as four 3-D Universes of which we are one will come together to form one 4-D expanding spatial Universe.展开更多
Conventional angle-tuned thin-film filters have serious angle sensitivity for their low spacer effective refractive index, and it is difficult to fabricate their angle control system. In this paper, we propose and fab...Conventional angle-tuned thin-film filters have serious angle sensitivity for their low spacer effective refractive index, and it is difficult to fabricate their angle control system. In this paper, we propose and fabricate a novel 100 GHz angletuned thin-film filter stack with low angle sensitivity, which uses the high refractive index material TiO2 as the spacer, and its incident angle can be expanded to 25°. Compared with the traditional Ta2O5-SiO2 thin-film filter stack, the novel stack has fewer layers. Using the polarization beam splitters and the half wave plates, the polarization sensitivity of the angle-tuned filter can also be suppressed. Simulation results and the experiments show that the thin-film filter with low angle sensitivity has an effective tuning range of 33 nm, which can cover the whole C-band, and its angle control system is easy to be fabricated.展开更多
Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate a...Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate anode materials impedes further applications. Herein, a novel self-template strategy is designed to synthesize uniform flowerlike N-doped hierarchical porous carbon networks (NHPCN) with high content of N (15.31 at.%) assembled by ultrathin nanosheets via a self-synthesized single precursor and subsequent thermal annealing. Relying on the synergetic coordination of benzimidazole and 2-methylimidazole with metal ions to produce a flowerlike network, a self-formed single precursor can be harvested. Due to the structural and compositional advantages, including the high N doping, the expanded interlayer spacing, the ultrathin two-dimensional nano-sized subunits, and the three-dimensional porous network structure, these unique NHPCN flowers deliver ultrahigh reversible capacities of 453.7 mAh·g^−1 at 0.1 A·g^−1 and 242.5 mAh·g^−1 at 1 A·g^−1 for 2,500 cycles with exceptional rate capability of 5 A·g^−1 with reversible capacities of 201.2 mAh·g^−1. The greatly improved sodium storage performance of NHPCN confirms the importance of reasonable engineering and synthesis of hierarchical carbon with unique structures.展开更多
VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer s...VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).展开更多
Aqueous zinc-ion batteries(AZIBs)have attracted extensive attention owing to their environmental friendliness and low cost.However,the application of AZIBs is hindered by the lack of suitable cathode materials due to ...Aqueous zinc-ion batteries(AZIBs)have attracted extensive attention owing to their environmental friendliness and low cost.However,the application of AZIBs is hindered by the lack of suitable cathode materials due to the sluggish kinetics of divalent Zn^(2+)in host materials.Herein,Se doped MoS_(2)nanosheets(MoS_(1.8)Se_(0.2))grown on reduced graphene oxide(rGO)are proposed as a promising cathode for AZIBs.Se doping generates expanded interlayer spacing and a high 1T phase(up to 64%)of MoS_(2),which improve its ion diffusion kinetics and electronic conductivity.Remarkably,the MoS_(1.8)Se_(0.2)/rGO cathode exhibits a high capacity of 213.6 mA h g^(-1)at 0.1 A g^(-1),excellent rate capability of 62.2 mA h g^(-1)at 8.0 A g^(-1),and long-term stability with 74.1%capacity retention after 1000 cycles at 1.0 A g^(-1).Moreover,reversible H^(+)/Zn^(2+)co-insertion/extraction behaviors of MoS_(1.8)Se_(0.2)/rGO are revealed.This study proves that anion doping of metal sulfides is a feasible method to develop high-performance cathodes for AZIBs.展开更多
MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable inte...MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable interlayer spacing.Nonetheless,the self-restacking and sluggish ions diffusion kinetics performance of MXenes during the alkali metal ions insertion/extraction process severely impedes their cycle stability and rate capability.This paper proposes an aniline molecule welding strategy for welding p-phenylenediamine(PPDA)into the interlayers of Ti_(2)C through a dehydration condensation reaction.The welded PPDA molecules can contribute pillar effect to the layered structure of Ti_(2)C.The pillar effect effectively maintains the structural stability during the sodium ions insertion/extraction process and effectively expands the interlayer spacing of Ti_(2)C from 1.16 to 1.38 nm,thereby enhancing ions diffusion kinetics performance and improving the long-term cycle stability.The Ti_(2)C-PPDA demonstrates outstanding Na+storage capability,exhibiting a specific capacity of 100.2 mAh·g^(-1)at a current density of 0.1 A·g^(-1)over 960 cycles and delivering a remarkable rate capability 81.2 mAh·g^(-1)at a current density of 5 A·g^(-1).The study demonstrates that expanding interlayer spacing is a promising strategy to enhance the Na+storage capacity and improve long-term cycling stability,which provides significant guidance for the design of two-dimensional Na+storage materials with high-rate capability and cycle stability.展开更多
MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical...MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.21601029, 21601030)the Open Project Program of the State Key Laboratory of Inorganic Synthesis and Preparative Chemistry (Nos.2017-33, 2017-26)the Fundamental Research Funds for the Central Universities of China (No.N180503012)。
文摘MXene is a rising star of two-dimensional(2D)materials for energy relative applications,however,the traditional synthesis of MXene etched by hazard HF acid or LiF+HCl mixed solution is highly dangerous with the risk of splashing or pouring liquid solutions.In this work,we developed a water-free ionothermal synthesis of 2D Ti3C2 MXene via etching pristine Ti3AlC2 MAX in low-cost choline chloride and oxalic acid based deep eutectic solvents(DES)with the presence of NH4F,thus it was highly safe and convenient to operate solid precursor and product materials at room temperature.Benefited from the low vapor pressure and solvating properties of DES,the prepared Ti3C2(denoted as DES-Ti3C2)possessed a high purity up to 98% compared with 95% for HF etched Ti3C2(denoted as HF-Ti3C2).Notably,an expanded interlayer spacing of 1.35 nm could be achieved due to the intercalation of choline cations in DES-Ti3C2,larger than that of HF-Ti3C2(0.98 nm).As a result,the DES-Ti3C2 anodes exhibited enhanced lithium storage performance,such as high reversible capacity of 208 m Ah g-1at 0.5 A g-1,and long cycle life over 400 times,outperforming most reported pure MXene anodes.The ionothermal synthesis of MXene developed here may pave a new way to safely prepare other MXene for various energy relating applications.
基金Special Fund Project for Innovation Driven Development of Guangxi(Gui Ke AA17204037)Key Science and Technology Project of Guangxi(Gui Ke AA16380017)Team Project of Guangxi Academy of Agricultural Sciences(2015YT60).
文摘Fenlong Technology has been applied to increase yield by 20%-50%,improve quality by 5%,and retain water by 100%in 40 kinds of crop cultivated land and saline-alkali land in 26 provinces of China.This paper clarified for the first time the scientific theory system of Fenlong Technology using three-dimensional space resources"Fenlong Agricultural Nature Theory"and the development of the relative"limits"of agricultural growth,which provides a huge power support and natural force for expanding human living spaces.Through inventing and creating a scientific and technological system of farming tools,farming machinery,farming modes,and magic weapons for cultivation,Fenlong Technology can increase grain,promote ecological development,and greatly expand the living spaces of the Chinese nation and achieve sustainable development.Using Fenlong Technology,China has expanded from the current single"cultivated land agriculture"to the"big pattern agriculture"of Fenlong"cultivated land+saline land+degraded grassland+marginal land+desertified land+river water",flexibly used 147 million ha of"three-dimensional space resources"of land,and the newly increased food,meat,and fish can feed 300 million to 400 million people,increased the water storage by 100 billion m^(3),and reduced the collection of groundwater by 20 million to 60 billion m^(3).
基金National Natural Science Foundation of China(51874142)Pearl River S&T Nova Program of Guangzhou(201806010031)+3 种基金the Fundamental Research Funds for the Central Universities(2019JQ09)Guangdong Innovative and Entrepreneurial Research Team Program(2016ZT06N569)Tip-top Scientific and Technical Innovative Youth Talents of Guangdong Special Support Program(2019TQ05L903)Young Elite Scientists Sponsorship Program by CAST(2019QNRC001).
文摘Two-dimensional(2D)MoS_(2) nanomaterials have been extensively studied due to their special structure and high theoretical capacity,but it is still a huge challenge to improve its cycle stability and achieve superior fast charge and discharge performance.Herein,a facile one-step hydrothermal method is proposed to synthetize an ordered and self-assembled MoS_(2) nanoflower(MoS_(2)/C NF)with expanded interlayer spacing via embedding a carbon layer into the interlayer.The carbon layer in the MoS_(2) interlayer can speed the transfer of electrons,while the nanoflower structure promotes the ions transport and improves the structural stability during the charging/discharging process.Therefore,MoS_(2)/C NF electrode exhibits exceptional rate performance(318.2 and 302.3 mA·h·g^(-1) at 5.0 and 10.0 A·g^(-1),respectively)and extraordinary cycle durability(98.8%retention after 300 cycles at a current density of 1.0 A·g^(-1)).This work provides a simple and feasible method for constructing high-performance anode composites for sodium ion batteries with excellent cycle durability and fast charge/discharge ability.
基金This research is supported by the NSF from Shanghai Science and Technology Commission, No.01ZA14003.
文摘We study in this paper a Hilbert space HV associated with the coarse geometry of an infinite connected graph X(V, E) with vertex set V and edge set E. We show that X(V,E) is uniformly expanding if and only ifl2(V)can be continuously included in HV as a closed subspace,and that the inner product structure of HV is topologically invariant under uniform coarsening of the graph. We also discuss the functorial properties of these Hilbert spaces.
文摘Earth was broken for the ZTE R&D Building at theheadquarters on October 28, 2003. Hou Weigui,President of ZTE, delivered a speech on the cere-mony. He said:“As part of the development strate-gy of ZTE, the new building will play an importantrole in improving the overall R&D arrangement andthe environment of production and R&D, reducingthe operating cost and enhancing the image of thewhole company.”The R&D building will be the Shenzhen R&D
基金supported in part by the National Natural Science Foundation of China(62073301,62373162,62473349,U24A20268,62233007)the Shenzhen Science and Technology Program(JCYJ20240813114007010).
文摘Dear Editor,This letter investigates the problem of multi-dimension formation tracking(MDFT)for the cross-domain unmanned systems,including several interconnected agents,namely,unmanned aerial vehicles(UAVs)and unmanned surface vehicles(USVs).We assume that each agent suffers from by the mixed constraints on its velocity,control input and Euler angle.Solving the MDFT problem implies that 1)The virtual state of each USV is determined in the earth coordinate by expanding its 2D work space to the 3D space.
基金supported by the Jilin Province Science and Technology Development Program,China(Grant No.20250102013JC).
文摘Phase engineering has proven to be an effective strategy for achieving superior thermoelectric performance,while pressure is an excellent means of expanding the phase space of a material.In this paper,the effect of pressure-induced phase transition on improving the crystal symmetry and enhancing the thermoelectric properties of AgCrSe2 under high pressure and high temperature are reported.A structural phase transition from the low-symmetry R3m phase to the high-symmetry P3m1 phase is discovered below 1 GPa,which increases band degeneracy and contributes to a high electrical conductivity.For the metallic P3m1 phase,the electrons surrounding the Se2−anion gradually transfer to the Ag+and Cr3+cations as the pressure increases,decreasing the density of states around the Fermi level and thus optimizing the carrier concentration,thereby increasing the Seebeck coefficient while maintaining a high electrical conductivity.Consequently,an ultrahigh power factor of 864μW⋅m−1⋅K−2 is achieved at 5 GPa and 297 K.This study provides new insights into improving thermoelectric transport properties by applying physical pressure to enhance crystal symmetry and optimize thermoelectric parameters,and also indicates that phase engineering is a compelling strategy to discover or design novel high-performance thermoelectric materials starting from low-symmetry compounds.
基金funded by the Key Research and Development Program of Shaanxi Province(No.2024SFYBXM-669)the National Natural Science Foundation of China(No.42271078)。
文摘0 INTRODUCTION Due to the rapid population growth and the accelerated urbanization process,the contradiction between the demand for expanding ground space and the limited available land scale is becoming increasingly prominent.China has implemented and completed several largescale land infilling and excavation projects(Figure 1),which have become the main way to increase land resources and expand construction land.
基金Financial support from theNationalNatural Science Foundation of China(21771064)the JST-ERATO Yamauchi Materials Space-Tectonics Project(JPMJER2003)is gratefully acknowledged.This work was performed in part at the Queensland node of the Australian National Fabrication Facility,a companyestablished under the National Collaborative Research Infrastructure Strategy to provide nano and microfabrication facilities for Australia's researchersThe authors are also grateful to the Taif University Researchers Supporting Project number(TURSP-2020/03),Taif University,Taif,KSA.
文摘Aqueous magnesium ion supercapacitors(MISs)have attracted attention due to their safety,low cost and environmental friendliness.However,the cycling stability of MISs is usually not ideal due to magnesium ion plating in/stripping from the negative electrode materials.Here,we demonstrate that MoS_(2)with expanded interlayer spacing(E-MoS_(2)),obtained via a facile method,is a prospective negative electrode material for rechargeable MISs,because the expanded layer spacing reduces ion diffusion resistance and provides more active sites for ion interaction.
基金financial support from Natural Science Foundation(2016GGX104019)of Shandong Province.
文摘Layered MoS_(2)has been recognized as a promising low-cost alternative to Pt-based electrocatalysts towards the hydrogen evolution reaction(HER).Intensive interest has been mainly focused on designing MoS_(2)nanostructures with large amounts of active edge sites and fast charge transfer.Here we report the synthesis of vanadium and nitrogen co-doped MoS_(2)on reduced graphene oxide with new defect sites on the basal/edge planes and expanded interlayer spacing.
基金financially supported by the Shuguang Program from Shanghai Education Development Foundation and Shanghai Municipal Education Commission (18SG035)State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University (KF2015)。
文摘Layered structure MoS_(2) nanosheets have shown great potential for energy storage applications.However,the methodology for elaborately controllable growth of MoS_(2) onto carbonaceous matrix for promoting the electrochemical performance is highly desirable.Herein,a high-effective,all-in-one in-situ conversion growth strategy has been proposed to construct a stable sandwich-type nanostructure.The formation of the optimized C-MoS_(2)/NCNTs product undergoes a dissolution-recrystallization process,in which ultra-thin carbon layer-coated MoS_(2) nanosheets densely assembled onto the surface of polyimide(PI)derived N-doped carbon nanotubes(CNTs).Theoretical simulation reveals that MoS_(2) nanosheets possessing an expanded interlayer spacing of 0.92 nm can greatly reduce the barrier energy of Na ions mitigation.Ac-cordingly,the as-made C-MoS_(2)/NCNTs anode delivers superior cycling stability(82%capacity retention after 400 cycles at 1 A g^(−1))and rate performance(348 mAh g^(−1) at 2 A g^(−1)).The results demonstrate that the expanded MoS_(2) interlayer distance,ultrathin outer carbon coating,and N-doped CNTs matrix together accounts for the outstanding sodium storage capability for the C-MoS_(2)/NCNTs electrode.
文摘We use experimental data from Distant Type 1a Supernovae to calculate the Observed Magnitude (m - M) which is the Apparent Magnitude (m) minus the Absolute Magnitude (M) for different values of the Redshift z which gives us the Distance Modulus. Then, we calculate the average velocity and average acceleration for different z values and plot them as a function of time. The expansion of the space of our 3-D Universe is exponential and it will end with a Big Bang as four 3-D Universes of which we are one will come together to form one 4-D expanding spatial Universe.
基金supported by the Scientific Research Project of Hubei Education Department(No.B2014246)the National Natural Science Foundation of China(No.61205062)+1 种基金the Natural Science Foundation of Hubei Province in China(No.2012FFB02701)the Project of Hubei Province Universities Outstanding Youth Scientific Innovation Team(No.T201431)
文摘Conventional angle-tuned thin-film filters have serious angle sensitivity for their low spacer effective refractive index, and it is difficult to fabricate their angle control system. In this paper, we propose and fabricate a novel 100 GHz angletuned thin-film filter stack with low angle sensitivity, which uses the high refractive index material TiO2 as the spacer, and its incident angle can be expanded to 25°. Compared with the traditional Ta2O5-SiO2 thin-film filter stack, the novel stack has fewer layers. Using the polarization beam splitters and the half wave plates, the polarization sensitivity of the angle-tuned filter can also be suppressed. Simulation results and the experiments show that the thin-film filter with low angle sensitivity has an effective tuning range of 33 nm, which can cover the whole C-band, and its angle control system is easy to be fabricated.
基金The work was financially supported by the National Natural Science of Foundation of China(No.51672114)the Natural Science Foundation of Jiangsu Province(No.BK20181469)the Zhenjiang Key Research and Development Project(Social Development)(No.SSH20190140049).
文摘Sodium-ion batteries (SIBs) have been attracting considerable attention as a promising candidate for large-scale energy storage because of the abundance and low-cost of sodium resources. However, lack of appropriate anode materials impedes further applications. Herein, a novel self-template strategy is designed to synthesize uniform flowerlike N-doped hierarchical porous carbon networks (NHPCN) with high content of N (15.31 at.%) assembled by ultrathin nanosheets via a self-synthesized single precursor and subsequent thermal annealing. Relying on the synergetic coordination of benzimidazole and 2-methylimidazole with metal ions to produce a flowerlike network, a self-formed single precursor can be harvested. Due to the structural and compositional advantages, including the high N doping, the expanded interlayer spacing, the ultrathin two-dimensional nano-sized subunits, and the three-dimensional porous network structure, these unique NHPCN flowers deliver ultrahigh reversible capacities of 453.7 mAh·g^−1 at 0.1 A·g^−1 and 242.5 mAh·g^−1 at 1 A·g^−1 for 2,500 cycles with exceptional rate capability of 5 A·g^−1 with reversible capacities of 201.2 mAh·g^−1. The greatly improved sodium storage performance of NHPCN confirms the importance of reasonable engineering and synthesis of hierarchical carbon with unique structures.
基金The authors are grateful to the National Key Research and Development Project(No.51890863)the National Natural Science Foundation of China(NSFC,Nos.51872172 and 51972197)+2 种基金the Natural Science Foundation of Shandong Province(Nos.ZR2018MEM010 and ZR2019MEM021)Major Research and Development Program for Public Welfare in Shandong(No.2018GGX102021)Young Scholars Program of Shandong University.
文摘VS2 with natural layered structure and metallic conductivity is a prospective candidate for sodium-ion batteries(SIBs)and potassium-ion batteries(PIBs).However,due to large radius of Na+and K+,the limited interlayer spacing(0.57 nm)of VS2 generally determines high ion diffusion barrier and large volume variation,resulting in unsatisfactory electrochemical performance of SIBs and PIBs.In this work,flower-like VS_(2)/N-doped carbon(VS_(2)/N-C)with expanded(001)plane is grown on reduced graphene oxide(rGO)via a solvothermal and subsequently carbonization strategy.In the VS_(2)/N-C@rGO nanohybrids,the ultrathin VS2"petals"are alternately intercalated by the N-doped porous carbon monolayers to achieve an expanded interlayer spacing(1.02 nm),which can effectively reduce ions diffusion barrier,expose abundant active sites for Na+/K+intercalation,and tolerate large volume variation.The N-C and rGO carbonous materials can significantly promote the electrical conductivity and structural stability.Benefited from the synergistic effect,the VS2/N-C@rGO electrode exhibits large reversible capacity(Na+:407 mAh·g^(-1) at 1 A·g^(-1);K^(+):334 mAh·g^(-1) at 0.2 A·g^(-1)),high rate capacity(Na+:273 mAh·g^(-1) at 8 A·g^(-1);K+:186 mAh·g^(-1) at 5 A·g^(-1)),and remarkable cycling stability(Na+:316 mAh·g^(-1) at 2 A·g^(-1) after 1,400 cycles;K^(+):216 mAh·g^(-1) at 1 A·g^(-1) after 500 cycles).
基金supported by the Natural Science Foundation of Hunan Province(2021JJ30094)the National Natural Science Foundation of China(22379041 and 52103313)the Science and Technology Innovation Program of Hunan Province(2023RC1045).
文摘Aqueous zinc-ion batteries(AZIBs)have attracted extensive attention owing to their environmental friendliness and low cost.However,the application of AZIBs is hindered by the lack of suitable cathode materials due to the sluggish kinetics of divalent Zn^(2+)in host materials.Herein,Se doped MoS_(2)nanosheets(MoS_(1.8)Se_(0.2))grown on reduced graphene oxide(rGO)are proposed as a promising cathode for AZIBs.Se doping generates expanded interlayer spacing and a high 1T phase(up to 64%)of MoS_(2),which improve its ion diffusion kinetics and electronic conductivity.Remarkably,the MoS_(1.8)Se_(0.2)/rGO cathode exhibits a high capacity of 213.6 mA h g^(-1)at 0.1 A g^(-1),excellent rate capability of 62.2 mA h g^(-1)at 8.0 A g^(-1),and long-term stability with 74.1%capacity retention after 1000 cycles at 1.0 A g^(-1).Moreover,reversible H^(+)/Zn^(2+)co-insertion/extraction behaviors of MoS_(1.8)Se_(0.2)/rGO are revealed.This study proves that anion doping of metal sulfides is a feasible method to develop high-performance cathodes for AZIBs.
基金supported by the National Natural Science Foundation of China(No.52062030)the Key Program of the Natural Science Foundation of Gansu Province(23JRRA789)。
文摘MXenes obtained significant attention in the field of energy storage devices due to their characteristic layered structure,modifiable surface functional groups,large electrochemically active surface,and regulable interlayer spacing.Nonetheless,the self-restacking and sluggish ions diffusion kinetics performance of MXenes during the alkali metal ions insertion/extraction process severely impedes their cycle stability and rate capability.This paper proposes an aniline molecule welding strategy for welding p-phenylenediamine(PPDA)into the interlayers of Ti_(2)C through a dehydration condensation reaction.The welded PPDA molecules can contribute pillar effect to the layered structure of Ti_(2)C.The pillar effect effectively maintains the structural stability during the sodium ions insertion/extraction process and effectively expands the interlayer spacing of Ti_(2)C from 1.16 to 1.38 nm,thereby enhancing ions diffusion kinetics performance and improving the long-term cycle stability.The Ti_(2)C-PPDA demonstrates outstanding Na+storage capability,exhibiting a specific capacity of 100.2 mAh·g^(-1)at a current density of 0.1 A·g^(-1)over 960 cycles and delivering a remarkable rate capability 81.2 mAh·g^(-1)at a current density of 5 A·g^(-1).The study demonstrates that expanding interlayer spacing is a promising strategy to enhance the Na+storage capacity and improve long-term cycling stability,which provides significant guidance for the design of two-dimensional Na+storage materials with high-rate capability and cycle stability.
基金The authors are grateful to the National Key Research and Development Project(No.51890863)the National Natural Science Foundation of China(Nos.51872172 and 51972197)+1 种基金Natural Science Foundation of Shandong Province(Nos.ZR2019MEM021 and ZR2020QE067)Young Scholars Program of Shandong University.
文摘MoS2 is considered as an ideal electrode material in the field of energy storage due to high theoretical specific capacity and unique layered structure.However,limited interlayer distance and poor intrinsic electrical conductivity restrict its potential realworld application.Herein,an alternately intercalated structure of MoS2 monolayer and N-doped porous carbon(NC)layer is grown on reduced graphene oxide(rGO)via a chemical intercalated strategy.The expanded interlayer distance of MoS2(0.96 nm),enlarged by the intercalation of N-doped porous carbon layers,can enhance ion diffusion mobility,provide additional reactive sites for ion storage and maintain the stability of electrode structure.In addition,the hierarchical structures between rGO substrate and intercalated N-doped carbon layers construct a three-dimensional(3D)conductive network,which can significantly improve the electrical conductivity and the structural stability.As a result,the rGO-supported MoS2/NC electrode exhibits an ultrahigh reversible capacity and remarkable long cycling stability for sodium-ion batteries(SIBs)and potassium-ion(PIBs).Meanwhile,the as-obtained MoS2/NC@rGO electrode also delivers a superior cycle performance of 250 mAh·g−1 after 160 cycles at 0.5 A·g−1 when employed as an anode for sodium-ion full cells.
