Surface potential decay of polymers for electrical insulation can help to determine the dark conductivity for spacecraft charging analysis. Due to the existence of radiation-induced conductivity, it decays fast in the...Surface potential decay of polymers for electrical insulation can help to determine the dark conductivity for spacecraft charging analysis. Due to the existence of radiation-induced conductivity, it decays fast in the first few hours after irradiation and exponentially slowly for the remaining time. The measurement of dark conductivity with this method usually takes the slow part and needs a couple of days. Integrating the Fowler formula into the deep dielectric charging equations, we obtain a new expression for the fast decay part. The experimental data of different materials, dose rates and temperatures are fitted by the new expression. Both the dark conductivity and the radiation-induced conductivity are derived and compared with other methods. The result shows a good estimation of dark conductivity and radiation-induced conductivity in high-resistivity polymers, which enables a fast measurement of dielectric conductivity within about 600 rain after irradiation.展开更多
Sodium-based dual-ion batteries(SDIBs) have gained tremendous attention due to their virtues of high operating voltage and low cost, yet it remains a tough challenge for the development of ideal anode material of SDIB...Sodium-based dual-ion batteries(SDIBs) have gained tremendous attention due to their virtues of high operating voltage and low cost, yet it remains a tough challenge for the development of ideal anode material of SDIBs featuring with high kinetics and long durability. Herein, we report the design and fabrication of N-doped carbon film-modified niobium sulfur–selenium(NbSSe/NC) nanosheets architecture, which holds favorable merits for Na^(+) storage of enlarged interlayer space, improved electrical conductivity, as well as enhanced reaction reversibility, endowing it with high capacity, high-rate capability and high cycling stability. The combined electrochemical studies with density functional theory calculation reveal that the enriched defects in such nanosheets architecture can benefit for facilitating charge transfer and Na+ adsorption to speed the electrochemical kinetics. The NbSSe/NC composites are studied as the anode of a full SDIBs by pairing the expanded graphite as cathode, which shows an impressively cyclic durability with negligible capacity attenuation over 1000 cycles at 0.5 A g^(-1), as well as an outstanding energy density of 230.6 Wh kg^(-1) based on the total mass of anode and cathode.展开更多
Lithium ion batteries are important electrochemical energy storage devices for consumer electronics and the most promising candidates for electrical/hybrid vehicles. The surface chemistry influences the performance of...Lithium ion batteries are important electrochemical energy storage devices for consumer electronics and the most promising candidates for electrical/hybrid vehicles. The surface chemistry influences the performance of the batteries significantly. In this short review, the ewlution of the surface struture of the cathode materials at different states of the pristine, storage and electrochemical reaclions are summarized. The main methods for the surface modification are also introduced.展开更多
Based on an orthogonal frequency division multiplexing(OFDM) training symbol with L identical parts, a novel carrier frequency offset (CFO) estimator is proposed for OFDM systems. The CFO is estimated in two steps, fi...Based on an orthogonal frequency division multiplexing(OFDM) training symbol with L identical parts, a novel carrier frequency offset (CFO) estimator is proposed for OFDM systems. The CFO is estimated in two steps, fine estimate and coarse estimate. In the first step, the fine estimation is performed based on the principle of minimum variance. However, the fine estimation has ambiguity since its estimate range is limited. In the second step, the coarse estimation is obtained, which results in a larger estimate range but less precision. Using the coarse estimation, the ambiguity of fine estimation is resolved. To fully use the correlation among L identical parts, the fine estimation resolved the ambiguity and the coarse estimation are optimally combined to obtain the final estimation. Furthermore, the estimation variance of the proposed method is derived. Simulation results demonstrate that the novel two-step estimator outperforms the conventional two-step estimator in terms of estimate performance and computational complexity.展开更多
A scheme is proposed to generate genuine tripartite Einstein-Podolsky-Rosen(EPR)steering in cascaded nonlinear process of the fourth-harmonic generation.The second-harmonic is generated by the first double-frequency p...A scheme is proposed to generate genuine tripartite Einstein-Podolsky-Rosen(EPR)steering in cascaded nonlinear process of the fourth-harmonic generation.The second-harmonic is generated by the first double-frequency process in an optical superlattice.Then,the fourth-harmonic is produced by the second cascaded double-frequency process through quasi-phase-matching technique in the same optical superlattice.The genuine tripartite EPR steering among the pump,the second-harmonic,and the fourth-harmonic beams can be obtained by this cascaded nonlinear process according to a criterion for genuine multipartite quantum steering.The quantum steering properties are discussed by adjusting the parameters related to the cascaded nonlinear system.The present research provides a reference scheme and data for obtaining good multipartite EPR steering in experiment and can advance the applications of quantum steering in the quantum information processing.展开更多
Nucleophile oxidation reaction(NOR), represented by ethanol oxidation reaction(EOR), is a promising pathway to replace oxygen evolution reaction(OER). EOR can effectively reduce the driving voltage of hydrogen product...Nucleophile oxidation reaction(NOR), represented by ethanol oxidation reaction(EOR), is a promising pathway to replace oxygen evolution reaction(OER). EOR can effectively reduce the driving voltage of hydrogen production in direct water splitting. In this work, large current and high efficiency of EOR on a Ni, Fe layered double hydroxide(NiFe-LDH) catalyst were simultaneously achieved by a facile fluorination strategy. F in NiFe-LDH can reduce the activation energy of the dehydrogenation reaction, thus promoting the deprotonation process of NiFe-LDH to achieve a lower EOR onset potential. It also weakens the absorption of OH-and nucleophile electrooxidation products on the surface of NiFe-LDH at a higher potential, achieving a high current density and EOR selectivity, according to density functional theory calculations. Based on our experiment results, the optimized fluorinated NiFe-LDH catalyst achieves a low potential of 1.386 V to deliver a 10 mA cm^(-2)EOR. Moreover, the Faraday efficiency is greater than 95%, with a current density ranging from 10 to 250 mA cm^(-2). This work provides a promising pathway for an efficient and cost-effective NOR catalyst design for economic hydrogen production.展开更多
High-voltage nickel(Ni)-rich layered oxide-based lithium metal batteries(LMBs)exhibit a great potential in advanced batteries due to the ultra-high energy density.However,it is still necessary to deal with the challen...High-voltage nickel(Ni)-rich layered oxide-based lithium metal batteries(LMBs)exhibit a great potential in advanced batteries due to the ultra-high energy density.However,it is still necessary to deal with the challenges in poor cyclic and thermal stability before realizing practical application where cycling life is considered.Among many improved strategies,mechanical and chemical stability for the electrode electrolyte interface plays a key role in addressing these challenges.Therefore,extensive effort has been made to address the challenges of electrode-electrolyte interface.In this progress,the failure mechanism of Ni-rich cathode,lithium metal anode and electrolytes are reviewed,and the latest breakthrough in stabilizing electrode-electrolyte interface is also summarized.Finally,the challenges and future research directions of Ni-rich LMBs are put forward.展开更多
Novel cost-effective fuel cells have become more attractive due to the demands for rare and expensive platinum-group metal(PGM)catalysts for mitigating the sluggish kinetics of the oxygen reduction reaction(ORR).The h...Novel cost-effective fuel cells have become more attractive due to the demands for rare and expensive platinum-group metal(PGM)catalysts for mitigating the sluggish kinetics of the oxygen reduction reaction(ORR).The high-cost PGM catalyst in fuel cells can be replaced by earth-abundant transition-metalbased catalysts,that is,an Fe-N-C catalyst,which is considered one of the most promising alternatives.However,the performance of the Fe-N-C catalyst is hindered by the low catalytic activity and poor stability,which is caused by insufficient active sites and the lack of optimization of the triple-phase interface for mass transportation.Herein,a novel Fe–N–C catalyst consisting of mono-dispersed hierarchically mesoporous carbon sphere cores and single Fe atom-dispersed functional shells are presented.The synergistic effect between highly dispersed Fe-active sites and well-organized porous structures yields the combination of high ORR activity and high mass transfer performance.The half-wave potential of the catalyst in 0.1M H_(2)SO_(4) is 0.82 V versus reversible hydrogen electrode,and the peak power density is 812 mW·cm^(−2) in H_(2)–O_(2) fuel cells.Furthermore,it shows superior methanol tolerance,which is almost immune to methanol poisoning and generates up to 162 mW·cm^(−2) power density in direct methanol fuel cells.展开更多
In order to improve the performance of the dye-sensitized solar cells based on ZnO films, ZnO nanoparticles of different sizes were prepared by two methods. Some surfactants were added into the particles to form three...In order to improve the performance of the dye-sensitized solar cells based on ZnO films, ZnO nanoparticles of different sizes were prepared by two methods. Some surfactants were added into the particles to form three types of ZnO pastes. Electrodes of various thickness applied to dye-sensitized solar cell were prepared starting from each of those pastes by the screen-printing method. The performance of dye-sensitized solar cells was optimized via both the selected particle size and film thickness. The reason of the inefficiency was explained by the infrared and ultraviolet- visible absorption spectra.展开更多
The p-GaAs/n-InP heterojunction was fabricated by direct wafer bonding technology. The optimized atomic level contact between GaAs and InP is critical for getting good ohmic contact and removing the bubbles or voids a...The p-GaAs/n-InP heterojunction was fabricated by direct wafer bonding technology. The optimized atomic level contact between GaAs and InP is critical for getting good ohmic contact and removing the bubbles or voids at the interface, which is helpful to enhance the efficiency of wafer bonded multi-junction solar cells. Through the surface megasonic cleaning and the plasma treatment, we have achieved the high quality bonding interface without bubbles or voids and with interface resistivity of about 0.1 ohms/cm^2. A GaInP/GaAs//InGaAsP/InGaAs 4-junction solar cell was prepared with the high efficiency of 34.4%(AM0)at 1 sun.展开更多
Based on the production of a carbon nanotube (CNT) assembly, a new technique is developed for preparing CNT/epoxy (EP) composite films with high tensile strength and electrical conductivity. CNTs are synthesized by fl...Based on the production of a carbon nanotube (CNT) assembly, a new technique is developed for preparing CNT/epoxy (EP) composite films with high tensile strength and electrical conductivity. CNTs are synthesized by floating catalyst spray pyrolysis. After self-assembling into a hollow cylindrical assembly, CNTs are drawn and wound on a rotating drum to form a uniform CNT film. EP resin solutions of different concentrations are used to fill into the pores within the film under different pressures and form composite films after hot-press curing. The permeability of the EP resin and thus the interfacial bonding between the CNT and the EP resin are studied by varying the concentration of the EP resin solution and the pressure used for impregnation. Under optimal preparation conditions, the composite film contains CNTs of a high content of 59 wt.%, and shows a high tensile strength of 1.4 GPa and a high electrical conductivity of 1.4x10^5 S·m^-1, 159% and 309% higher than those of the neat CNT film, respectively.展开更多
Electrochemically synthesized nanosphere,nanorod and nanotube Fe_(2)(MoO_(4))_(3) at optimized temperature and current density are characterized with XRD,SEM,TEM,XPS.Crystal lattices of the three types Fe_(2)(MoO_(4))...Electrochemically synthesized nanosphere,nanorod and nanotube Fe_(2)(MoO_(4))_(3) at optimized temperature and current density are characterized with XRD,SEM,TEM,XPS.Crystal lattices of the three types Fe_(2)(MoO_(4))_(3) detected by HRTEM are well matched with the simulation analysis results from Materials Studio 6.0 based on the inorganic crystal structure database(ICSD)data and the modified XRD lattice parameters.The ratios of Fe/Mo on the surface resulted from XPS analysis are 1.47,1.63 and 2.22 respectively for nanosphere,nanorod and nanotube.The mixture of Fe_(2)(MoO_(4))_(3) with polytetrafluoroethylene dispersion are coated on glass carbon substrate as electrode for electrocatalytic performance test by cyclic voltammetries in 0.1 mol/L KOH and 1 mol/L methanol electrolyte.Methanol oxidation peak current density of the Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs electrode is 3.27 mA/cm^(2) higher than 2.8 mA/cm^(2) of platinum foil electrode,which shows enhanced catalytic activity of Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs.The cyclic stability in terms of peak current retention are 91%,92%and 88%respectively for Nanosphere-Fe_(2)(MoO_(4))_(3)/GCE,Nanorod-Fe_(2)(MoO_(4))_(3)/GCE and Nanotube-Fe_(2)(MoO_(4))_(3)/GCE electrode after 220 cycles.It is concluded that nanosized Fe_(2)(MoO_(4))_(3) could be promising alternative non-noble electro-catalysts for electro-oxidation of methanol in alkaline medium.展开更多
The practical application of Pyrite iron disulfide (FeS_(2)) as anode material of sodium-ion battery is limitedby its low electronic conductivity, large volume changes during charge/discharge. To overcome thesechallen...The practical application of Pyrite iron disulfide (FeS_(2)) as anode material of sodium-ion battery is limitedby its low electronic conductivity, large volume changes during charge/discharge. To overcome thesechallenges, a novel structure design single-walled carbon nanotubes (SWCNTs) composited polyaniline(PANI)-wrapped FeS_(2) (FeS_(2)-PANI-SWCNTs) electrodes are successfully achieved in this work. PANI canprotect the FeS_(2) particles from collapse and offer a protective layer to relive the polysulfides shuttlingeffect, and also promote the electron and Naþ diffusion during the chemical conversion process. Underthe dual protection of PANI and SWCNTs, the FeS_(2)-PANI-SWCNTs film electrode demonstrates a goodstructural integrity, which accounts for the excellent rate capability and long cycling performance. Inaddition, the PANI coating and SWCNT network in the fabricated electrode can synergistically anchorpolysulfides and therefore strongly suppress shuttle effect during the chargeedischarge processes,resulting in less capacity loss. The anode with a loading 3.2 mg cm 2 of FeS_(2) coated with PANI exhibitsthe initial coulombic efficiency of 81.5% and delivers a specific capacity of 625.8 mAh g^(-1) after 100 cyclesat 200 mA g^(-1). High flexible and binder-free FeS_(2)-PANI-SWCNTs film anode demonstrates a reversiblecapacity of 537 mAh g^(-1) after 550 cycles at 1 A g^(-1). This research may offer an efficient method toimprove electrochemical performance of the metal sulfides in sodium-ion batteries.展开更多
Electrochemical CO_(2)reduction is a typical surface-mediated reaction,with its reaction kinetics and product distributions largely dependent on the dynamic evolution of reactive species at the cathode–catholyte inte...Electrochemical CO_(2)reduction is a typical surface-mediated reaction,with its reaction kinetics and product distributions largely dependent on the dynamic evolution of reactive species at the cathode–catholyte interface and on the resultant mass transport within the hydrodynamic boundary layer in the vicinity of the cathode.To resolve the complex local reaction environment of branching CO_(2)reduction pathways,we here present a dif-ferential electrochemical mass spectroscopic(DEMS)approach for Cu electrodes to investigate CO_(2)mass trans-port,the local concentration gradients of buffering anions,and the Cu surface topology effects on CO_(2)electrolysis selectivity at a temporal resolution of~400 ms.As a proof of concept,these tuning knobs were validated on an anion exchange membrane electrolyzer,which delivered a Faradaic efficiency of up to 40.4%and a partial current density of 121 mA cm^(-2)for CO_(2)-to-C_(2)H_(4)valorization.This methodology,which bridges the study of fundamental surface electrochemistry and the upgrading of practical electrolyzer performance,could be of general interest in helping to achieve a sustainable circular carbon economy.展开更多
The development of high-performance lithium ion batteries requires the discovery of new materials and the optimization of key components.By contrast with traditional one-by-one method,high-throughput method can synthe...The development of high-performance lithium ion batteries requires the discovery of new materials and the optimization of key components.By contrast with traditional one-by-one method,high-throughput method can synthesize and characterize a large number of compositionally varying samples,which is able to accelerate the pace of discovery,development and optimization process of materials.Because of rapid progress in thin film and automatic control technologies,thousands of compounds with different compositions could be synthesized rapidly right now,even in a single experiment.However,the lack of rapid or combinatorial characterization technologies to match with high-throughput synthesis methods,limit the application of high-throughput technology.Here,we review a series of representative highthroughput characterization methods used in lithium batteries,including high-throughput structural and electrochemical characterization methods and rapid measuring technologies based on synchrotron light sources.展开更多
As a promising renewable energy source,it is a challenging task to obtain blue energy,which is irregular and has an ultralow frequency,due to the limitation of technology.Herein,a nonresonant hybridized electromagneti...As a promising renewable energy source,it is a challenging task to obtain blue energy,which is irregular and has an ultralow frequency,due to the limitation of technology.Herein,a nonresonant hybridized electromagnetic-triboelectric nanogenerator was presented to efficiently obtain the ultralow frequency energy.The instrument adopted the flexible pendulum structure with a precise design and combined the working principle of electromagnetism and triboelectricity to realize the all-directional vibration energy acquisition successfully.The results confirmed that the triboelectric nanogenerator(TENG)had the potential to deliver the maximum power point of about 470μW while the electromagnetic nanogenerator(EMG)can provide 523 mW at most.The conversion efficiency of energy of the system reached 48.48%,which exhibited a remarkable improvement by about 2.96 times,due to the elastic buffering effect of the TENG with the double helix structure.Furthermore,its ability to collect low frequency wave energy was successfully proven by a buoy in Jialing River.This woke provides an effective candidate to harvest irregular and ultralow frequency blue energy on a large scale.展开更多
Searching for light and miniaturized functional device structures for sustainable energy gathering from the environment is the focus of energy society with the development of the internet of things.The proposal of a d...Searching for light and miniaturized functional device structures for sustainable energy gathering from the environment is the focus of energy society with the development of the internet of things.The proposal of a dynamic heterojunction-based direct current generator builds up new platforms for developing in situ energy.However,the requirement of different semiconductors in dynamic heterojunction is too complex to wide applications,generating energy loss for crystal structure mismatch.Herein,dynamic homojunction generators are explored,with the same semiconductor and majority carrier type.Systematic experiments reveal that the majority of carrier directional separation originates from the breaking symmetry between carrier distribution,leading to the rebounding effect of carriers by the interfacial electric field.Strikingly,NN Si homojunction with different Fermi levels can also output the electricity with higher current density than PP/PN homojunction,attributing to higher carrier mobility.The current density is as high as 214.0 A/m^(2),and internal impedance is as low as 3.6 kΩ,matching well with the impedance of electron components.Furthermore,the N-i-N structure is explored,whose output voltage can be further improved to 1.3V in the case of the N-Si/Al2O3/N-Si structure,attributing to the enhanced interfacial barrier.This approach provides a simple and feasible way of converting low-frequency disordered mechanical motion into electricity.展开更多
The in-plane thermal conductivity of the iron-based superconductor Ca10(Pt_(4-δ)As_8)((Fe_(1-x)Pt_x)_2As_2)_5 single crystal("10-4-8", T c= 22 K) was measured down to 80 m K. In a zero field, the residual l...The in-plane thermal conductivity of the iron-based superconductor Ca10(Pt_(4-δ)As_8)((Fe_(1-x)Pt_x)_2As_2)_5 single crystal("10-4-8", T c= 22 K) was measured down to 80 m K. In a zero field, the residual linear term κ_0/T is negligible, suggesting the nodeless superconducting gaps in this multiband compound. In the magnetic fields, κ_0/T increases rapidly, which mimics the multiband superconductor Nb Se_2 and Lu Ni_2B_2 C with highly anisotropic gap. Such a field dependence of κ_0/T is an evidence for the multiple superconducting gaps with quite different magnitudes or highly anisotropic gap. Compared with the London penetration depth results of the Ca10(Pt_(4-δ)As_8)((Fe_(1-x)Pt_x)_2As_2)_5("10-3-8") compound, the 10-4-8 and 10-3-8 compounds may have a similar superconducting gap structure.展开更多
Direct wafer bonding technology is able to integrate two smooth wafers and thus can be used in fab- ricating III-V multijunction solar cells with lattice mismatch. In order to monolithically interconnect between the G...Direct wafer bonding technology is able to integrate two smooth wafers and thus can be used in fab- ricating III-V multijunction solar cells with lattice mismatch. In order to monolithically interconnect between the GalnP/GaAs and InGaAsP/InGaAs subcells, the bonded GaAs/InP heterojunction must be a highly conductive ohmic junction or a tunnel junction. Three types of bonding interfaces were designed by tuning the conduction type and doping elements of GaAs and InP. The electrical properties of p-GaAs (Zn doped)/n-InP (Si doped), p- GaAs (C doped)/n-InP (Si doped) and n-GaAs (Si doped)/n-InP (Si doped) bonded heterojunctions were analyzed from the I-V characteristics. The wafer bonding process was investigated by improving the quality of the sample surface and optimizing the bonding parameters such as bonding temperature, bonding pressure, bonding time and so on. Finally, GalnP/GaAs/InGaAsP/lnGaAs 4-junction solar cells have been prepared by a direct wafer bonding technique with the high efficiency of 34.14% at the AM0 condition (1 Sun).展开更多
基金Supported by the Fundamental Research Funds for the Central Universities in Nanjing University of Aeronautics and Astronautics under Grant No NS2014089
文摘Surface potential decay of polymers for electrical insulation can help to determine the dark conductivity for spacecraft charging analysis. Due to the existence of radiation-induced conductivity, it decays fast in the first few hours after irradiation and exponentially slowly for the remaining time. The measurement of dark conductivity with this method usually takes the slow part and needs a couple of days. Integrating the Fowler formula into the deep dielectric charging equations, we obtain a new expression for the fast decay part. The experimental data of different materials, dose rates and temperatures are fitted by the new expression. Both the dark conductivity and the radiation-induced conductivity are derived and compared with other methods. The result shows a good estimation of dark conductivity and radiation-induced conductivity in high-resistivity polymers, which enables a fast measurement of dielectric conductivity within about 600 rain after irradiation.
基金financially supported by the National key Research & Development Program of China (2022YFE0115900, 2021YFA1501500)the National Natural Science Foundation of China (Nos. 22225902, U22A20436, 22209185)+3 种基金the CAS-Commonwealth Scientific and Industrial Research Organization (CSIRO) Joint Research Projects (121835KYSB20200039)the Joint Fund of the Yulin University and the Dalian National Laboratory for Clean Energy (Grant. YLUDNL Fund 2021011)Fujian Province Central Government Guides to Science and Technology Development Special Project (No. 2022L3024)Natural Science Foundation of Fujian Province, China (No. 2021J02020)。
文摘Sodium-based dual-ion batteries(SDIBs) have gained tremendous attention due to their virtues of high operating voltage and low cost, yet it remains a tough challenge for the development of ideal anode material of SDIBs featuring with high kinetics and long durability. Herein, we report the design and fabrication of N-doped carbon film-modified niobium sulfur–selenium(NbSSe/NC) nanosheets architecture, which holds favorable merits for Na^(+) storage of enlarged interlayer space, improved electrical conductivity, as well as enhanced reaction reversibility, endowing it with high capacity, high-rate capability and high cycling stability. The combined electrochemical studies with density functional theory calculation reveal that the enriched defects in such nanosheets architecture can benefit for facilitating charge transfer and Na+ adsorption to speed the electrochemical kinetics. The NbSSe/NC composites are studied as the anode of a full SDIBs by pairing the expanded graphite as cathode, which shows an impressively cyclic durability with negligible capacity attenuation over 1000 cycles at 0.5 A g^(-1), as well as an outstanding energy density of 230.6 Wh kg^(-1) based on the total mass of anode and cathode.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB07030200)the National Basic Research Program of China(Grant Nos.2014CB921002 and 2012CB921702)
文摘Lithium ion batteries are important electrochemical energy storage devices for consumer electronics and the most promising candidates for electrical/hybrid vehicles. The surface chemistry influences the performance of the batteries significantly. In this short review, the ewlution of the surface struture of the cathode materials at different states of the pristine, storage and electrochemical reaclions are summarized. The main methods for the surface modification are also introduced.
基金Foundation of Donghua University,China (No.104100044027)
文摘Based on an orthogonal frequency division multiplexing(OFDM) training symbol with L identical parts, a novel carrier frequency offset (CFO) estimator is proposed for OFDM systems. The CFO is estimated in two steps, fine estimate and coarse estimate. In the first step, the fine estimation is performed based on the principle of minimum variance. However, the fine estimation has ambiguity since its estimate range is limited. In the second step, the coarse estimation is obtained, which results in a larger estimate range but less precision. Using the coarse estimation, the ambiguity of fine estimation is resolved. To fully use the correlation among L identical parts, the fine estimation resolved the ambiguity and the coarse estimation are optimally combined to obtain the final estimation. Furthermore, the estimation variance of the proposed method is derived. Simulation results demonstrate that the novel two-step estimator outperforms the conventional two-step estimator in terms of estimate performance and computational complexity.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61975184,91636108,and 61775043)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY18A040007)+1 种基金the Science Foundation of Zhejiang Sci-Tech University(Grant Nos.19062151-Y and 18062145-Y)the Open Foundation of the Key Laboratory of Optical Field Manipulation of Zhejiang Province,China(Grant No.ZJOFM-2019-002).
文摘A scheme is proposed to generate genuine tripartite Einstein-Podolsky-Rosen(EPR)steering in cascaded nonlinear process of the fourth-harmonic generation.The second-harmonic is generated by the first double-frequency process in an optical superlattice.Then,the fourth-harmonic is produced by the second cascaded double-frequency process through quasi-phase-matching technique in the same optical superlattice.The genuine tripartite EPR steering among the pump,the second-harmonic,and the fourth-harmonic beams can be obtained by this cascaded nonlinear process according to a criterion for genuine multipartite quantum steering.The quantum steering properties are discussed by adjusting the parameters related to the cascaded nonlinear system.The present research provides a reference scheme and data for obtaining good multipartite EPR steering in experiment and can advance the applications of quantum steering in the quantum information processing.
基金the financial support from the National Natural Science Foundation of China (22197121)Knowledge Innovation Program of Wuhan-Basic Research (2022010801010202)Research Fund Program of Guangdong Provincial Key Laboratory of Fuel Cell Technology (FC202201)。
文摘Nucleophile oxidation reaction(NOR), represented by ethanol oxidation reaction(EOR), is a promising pathway to replace oxygen evolution reaction(OER). EOR can effectively reduce the driving voltage of hydrogen production in direct water splitting. In this work, large current and high efficiency of EOR on a Ni, Fe layered double hydroxide(NiFe-LDH) catalyst were simultaneously achieved by a facile fluorination strategy. F in NiFe-LDH can reduce the activation energy of the dehydrogenation reaction, thus promoting the deprotonation process of NiFe-LDH to achieve a lower EOR onset potential. It also weakens the absorption of OH-and nucleophile electrooxidation products on the surface of NiFe-LDH at a higher potential, achieving a high current density and EOR selectivity, according to density functional theory calculations. Based on our experiment results, the optimized fluorinated NiFe-LDH catalyst achieves a low potential of 1.386 V to deliver a 10 mA cm^(-2)EOR. Moreover, the Faraday efficiency is greater than 95%, with a current density ranging from 10 to 250 mA cm^(-2). This work provides a promising pathway for an efficient and cost-effective NOR catalyst design for economic hydrogen production.
基金National Natural Science Foundation of China,Grant/Award Numbers:U21A20311,51971090。
文摘High-voltage nickel(Ni)-rich layered oxide-based lithium metal batteries(LMBs)exhibit a great potential in advanced batteries due to the ultra-high energy density.However,it is still necessary to deal with the challenges in poor cyclic and thermal stability before realizing practical application where cycling life is considered.Among many improved strategies,mechanical and chemical stability for the electrode electrolyte interface plays a key role in addressing these challenges.Therefore,extensive effort has been made to address the challenges of electrode-electrolyte interface.In this progress,the failure mechanism of Ni-rich cathode,lithium metal anode and electrolytes are reviewed,and the latest breakthrough in stabilizing electrode-electrolyte interface is also summarized.Finally,the challenges and future research directions of Ni-rich LMBs are put forward.
基金We gratefully acknowledge support from the National Natural Science Foundation of China(Grant Nos.21905220,51772240,21503158,51425301,U1601214,21703184)the China Postdoctoral Science Foundation(2020M673408)+5 种基金the Key Research and Development Plan of Shaanxi Province,China(Grant No.2018ZDXM-GY-135)the Fundamental Research Funds for“Young Talent Support Plan”of Xi'an Jiaotong University(HG6J003)the“1000‐Plan program”of Shaanxi Province,the Promotion Program for Young and Middle-Aged Teacher in Science and Technology Research of Huaqiao University(ZQN-PY506)the Scientific Research Funds of Huaqiao University(17BS405)the State Key Laboratory for Mechanical Behavior of Materials(20192101)the Natural Science Foundation Committee of Jiangsu Province(BK20201190).
文摘Novel cost-effective fuel cells have become more attractive due to the demands for rare and expensive platinum-group metal(PGM)catalysts for mitigating the sluggish kinetics of the oxygen reduction reaction(ORR).The high-cost PGM catalyst in fuel cells can be replaced by earth-abundant transition-metalbased catalysts,that is,an Fe-N-C catalyst,which is considered one of the most promising alternatives.However,the performance of the Fe-N-C catalyst is hindered by the low catalytic activity and poor stability,which is caused by insufficient active sites and the lack of optimization of the triple-phase interface for mass transportation.Herein,a novel Fe–N–C catalyst consisting of mono-dispersed hierarchically mesoporous carbon sphere cores and single Fe atom-dispersed functional shells are presented.The synergistic effect between highly dispersed Fe-active sites and well-organized porous structures yields the combination of high ORR activity and high mass transfer performance.The half-wave potential of the catalyst in 0.1M H_(2)SO_(4) is 0.82 V versus reversible hydrogen electrode,and the peak power density is 812 mW·cm^(−2) in H_(2)–O_(2) fuel cells.Furthermore,it shows superior methanol tolerance,which is almost immune to methanol poisoning and generates up to 162 mW·cm^(−2) power density in direct methanol fuel cells.
基金supported by the National Basic Research Program of China (No. G2000028206)
文摘In order to improve the performance of the dye-sensitized solar cells based on ZnO films, ZnO nanoparticles of different sizes were prepared by two methods. Some surfactants were added into the particles to form three types of ZnO pastes. Electrodes of various thickness applied to dye-sensitized solar cell were prepared starting from each of those pastes by the screen-printing method. The performance of dye-sensitized solar cells was optimized via both the selected particle size and film thickness. The reason of the inefficiency was explained by the infrared and ultraviolet- visible absorption spectra.
基金supported by the Shanghai Rising-Star Program (No. 14QB1402800)
文摘The p-GaAs/n-InP heterojunction was fabricated by direct wafer bonding technology. The optimized atomic level contact between GaAs and InP is critical for getting good ohmic contact and removing the bubbles or voids at the interface, which is helpful to enhance the efficiency of wafer bonded multi-junction solar cells. Through the surface megasonic cleaning and the plasma treatment, we have achieved the high quality bonding interface without bubbles or voids and with interface resistivity of about 0.1 ohms/cm^2. A GaInP/GaAs//InGaAsP/InGaAs 4-junction solar cell was prepared with the high efficiency of 34.4%(AM0)at 1 sun.
基金the National Key R&D Program of China (2018YFA0208404)the National Natural Science Foundation of China (U1362104).
文摘Based on the production of a carbon nanotube (CNT) assembly, a new technique is developed for preparing CNT/epoxy (EP) composite films with high tensile strength and electrical conductivity. CNTs are synthesized by floating catalyst spray pyrolysis. After self-assembling into a hollow cylindrical assembly, CNTs are drawn and wound on a rotating drum to form a uniform CNT film. EP resin solutions of different concentrations are used to fill into the pores within the film under different pressures and form composite films after hot-press curing. The permeability of the EP resin and thus the interfacial bonding between the CNT and the EP resin are studied by varying the concentration of the EP resin solution and the pressure used for impregnation. Under optimal preparation conditions, the composite film contains CNTs of a high content of 59 wt.%, and shows a high tensile strength of 1.4 GPa and a high electrical conductivity of 1.4x10^5 S·m^-1, 159% and 309% higher than those of the neat CNT film, respectively.
基金This work was supported by the National Natural Science Foundation of China(No.21373137)National 863 program(No.2014AA052202)+1 种基金Shanghai Science and Technology Development Funds(No.13DZ2280200&No.15DZ2282000)SSM also thanks the support of Shenzhen Overseas High-Level Talent Innovation and Entrepreneurship Team special funds(No.1208040050847074).
文摘Electrochemically synthesized nanosphere,nanorod and nanotube Fe_(2)(MoO_(4))_(3) at optimized temperature and current density are characterized with XRD,SEM,TEM,XPS.Crystal lattices of the three types Fe_(2)(MoO_(4))_(3) detected by HRTEM are well matched with the simulation analysis results from Materials Studio 6.0 based on the inorganic crystal structure database(ICSD)data and the modified XRD lattice parameters.The ratios of Fe/Mo on the surface resulted from XPS analysis are 1.47,1.63 and 2.22 respectively for nanosphere,nanorod and nanotube.The mixture of Fe_(2)(MoO_(4))_(3) with polytetrafluoroethylene dispersion are coated on glass carbon substrate as electrode for electrocatalytic performance test by cyclic voltammetries in 0.1 mol/L KOH and 1 mol/L methanol electrolyte.Methanol oxidation peak current density of the Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs electrode is 3.27 mA/cm^(2) higher than 2.8 mA/cm^(2) of platinum foil electrode,which shows enhanced catalytic activity of Nanotube-Fe_(2)(MoO_(4))_(3)/GCEs.The cyclic stability in terms of peak current retention are 91%,92%and 88%respectively for Nanosphere-Fe_(2)(MoO_(4))_(3)/GCE,Nanorod-Fe_(2)(MoO_(4))_(3)/GCE and Nanotube-Fe_(2)(MoO_(4))_(3)/GCE electrode after 220 cycles.It is concluded that nanosized Fe_(2)(MoO_(4))_(3) could be promising alternative non-noble electro-catalysts for electro-oxidation of methanol in alkaline medium.
基金financial support by National Key Research and Development Program of China(2018YFB0104400)the Natural Science Foundation of Shanghai(21ZR1443200)+3 种基金Shanghai Rising-Star Program(No.20QB1401700,No.21QB1401400)the Science and Technology Commission of Shanghai Municipality(20511107800)Shanghai Sailing Program(18YF1417000)the University Scientific Research Project of Xinjiang Uygur Autonomous Region(XJEDU2018Y043).
文摘The practical application of Pyrite iron disulfide (FeS_(2)) as anode material of sodium-ion battery is limitedby its low electronic conductivity, large volume changes during charge/discharge. To overcome thesechallenges, a novel structure design single-walled carbon nanotubes (SWCNTs) composited polyaniline(PANI)-wrapped FeS_(2) (FeS_(2)-PANI-SWCNTs) electrodes are successfully achieved in this work. PANI canprotect the FeS_(2) particles from collapse and offer a protective layer to relive the polysulfides shuttlingeffect, and also promote the electron and Naþ diffusion during the chemical conversion process. Underthe dual protection of PANI and SWCNTs, the FeS_(2)-PANI-SWCNTs film electrode demonstrates a goodstructural integrity, which accounts for the excellent rate capability and long cycling performance. Inaddition, the PANI coating and SWCNT network in the fabricated electrode can synergistically anchorpolysulfides and therefore strongly suppress shuttle effect during the chargeedischarge processes,resulting in less capacity loss. The anode with a loading 3.2 mg cm 2 of FeS_(2) coated with PANI exhibitsthe initial coulombic efficiency of 81.5% and delivers a specific capacity of 625.8 mAh g^(-1) after 100 cyclesat 200 mA g^(-1). High flexible and binder-free FeS_(2)-PANI-SWCNTs film anode demonstrates a reversiblecapacity of 537 mAh g^(-1) after 550 cycles at 1 A g^(-1). This research may offer an efficient method toimprove electrochemical performance of the metal sulfides in sodium-ion batteries.
基金supported by the National Key R&D Program of China(2022YFB4102000,2022YFA1505100,2022YFA1503803)the NSFC(22002088)+1 种基金the Shanghai Sailing Program(20YF1420500)the Shanghai Science and Technology Innovation Action Plan(22dz1205500).
文摘Electrochemical CO_(2)reduction is a typical surface-mediated reaction,with its reaction kinetics and product distributions largely dependent on the dynamic evolution of reactive species at the cathode–catholyte interface and on the resultant mass transport within the hydrodynamic boundary layer in the vicinity of the cathode.To resolve the complex local reaction environment of branching CO_(2)reduction pathways,we here present a dif-ferential electrochemical mass spectroscopic(DEMS)approach for Cu electrodes to investigate CO_(2)mass trans-port,the local concentration gradients of buffering anions,and the Cu surface topology effects on CO_(2)electrolysis selectivity at a temporal resolution of~400 ms.As a proof of concept,these tuning knobs were validated on an anion exchange membrane electrolyzer,which delivered a Faradaic efficiency of up to 40.4%and a partial current density of 121 mA cm^(-2)for CO_(2)-to-C_(2)H_(4)valorization.This methodology,which bridges the study of fundamental surface electrochemistry and the upgrading of practical electrolyzer performance,could be of general interest in helping to achieve a sustainable circular carbon economy.
基金This work was supported by National Science Foundation of China(51602191,51602190)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning.
文摘The development of high-performance lithium ion batteries requires the discovery of new materials and the optimization of key components.By contrast with traditional one-by-one method,high-throughput method can synthesize and characterize a large number of compositionally varying samples,which is able to accelerate the pace of discovery,development and optimization process of materials.Because of rapid progress in thin film and automatic control technologies,thousands of compounds with different compositions could be synthesized rapidly right now,even in a single experiment.However,the lack of rapid or combinatorial characterization technologies to match with high-throughput synthesis methods,limit the application of high-throughput technology.Here,we review a series of representative highthroughput characterization methods used in lithium batteries,including high-throughput structural and electrochemical characterization methods and rapid measuring technologies based on synchrotron light sources.
基金support of the National Key Research and Development Program of China(Grant No.2019YFB2004800)the General Program of the National Natural Science Foundation of China(NSFC,No.52075061)+5 种基金the Fund for Cultivating Talent of Chongqing University(CQU2019HBRC1A04)the Research Funds from Shanghai Institute of Space Power-Source(YF07050118F5655)the National Key R&D Project from Minister of Science and Technology in China(No.2016YFA0202701)the National Natural Science Foundation of China(No.52072041)the University of Chinese Academy of Sciences(Grant No.Y8540XX2D2)The project was supported by the Graduate Scientific Research and Innovation Foundation of Chongqing(Grant No.GDYKC202004).
文摘As a promising renewable energy source,it is a challenging task to obtain blue energy,which is irregular and has an ultralow frequency,due to the limitation of technology.Herein,a nonresonant hybridized electromagnetic-triboelectric nanogenerator was presented to efficiently obtain the ultralow frequency energy.The instrument adopted the flexible pendulum structure with a precise design and combined the working principle of electromagnetism and triboelectricity to realize the all-directional vibration energy acquisition successfully.The results confirmed that the triboelectric nanogenerator(TENG)had the potential to deliver the maximum power point of about 470μW while the electromagnetic nanogenerator(EMG)can provide 523 mW at most.The conversion efficiency of energy of the system reached 48.48%,which exhibited a remarkable improvement by about 2.96 times,due to the elastic buffering effect of the TENG with the double helix structure.Furthermore,its ability to collect low frequency wave energy was successfully proven by a buoy in Jialing River.This woke provides an effective candidate to harvest irregular and ultralow frequency blue energy on a large scale.
基金This work was funded by the National Natural Science Foundation of China(Nos.51202216,51502264,and 61774135)Special Foundation of Young Professor of Zhejiang University(No.2013QNA5007)Y.Wen thanks the support from the Science and Technology Project of Jiangsu Province Special Equipment Safety Supervision and Inspection Institute(KJY2017016).
文摘Searching for light and miniaturized functional device structures for sustainable energy gathering from the environment is the focus of energy society with the development of the internet of things.The proposal of a dynamic heterojunction-based direct current generator builds up new platforms for developing in situ energy.However,the requirement of different semiconductors in dynamic heterojunction is too complex to wide applications,generating energy loss for crystal structure mismatch.Herein,dynamic homojunction generators are explored,with the same semiconductor and majority carrier type.Systematic experiments reveal that the majority of carrier directional separation originates from the breaking symmetry between carrier distribution,leading to the rebounding effect of carriers by the interfacial electric field.Strikingly,NN Si homojunction with different Fermi levels can also output the electricity with higher current density than PP/PN homojunction,attributing to higher carrier mobility.The current density is as high as 214.0 A/m^(2),and internal impedance is as low as 3.6 kΩ,matching well with the impedance of electron components.Furthermore,the N-i-N structure is explored,whose output voltage can be further improved to 1.3V in the case of the N-Si/Al2O3/N-Si structure,attributing to the enhanced interfacial barrier.This approach provides a simple and feasible way of converting low-frequency disordered mechanical motion into electricity.
基金supported by the National Basic Research Program of China(Grant No.2012CB821402)the National Natural Science Foundation of China(Grant Nos.11422429 and 91421101)+1 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learningthe Science and Technology Commission of Shanghai Municipality of China(Grant No.15XD1500200)
文摘The in-plane thermal conductivity of the iron-based superconductor Ca10(Pt_(4-δ)As_8)((Fe_(1-x)Pt_x)_2As_2)_5 single crystal("10-4-8", T c= 22 K) was measured down to 80 m K. In a zero field, the residual linear term κ_0/T is negligible, suggesting the nodeless superconducting gaps in this multiband compound. In the magnetic fields, κ_0/T increases rapidly, which mimics the multiband superconductor Nb Se_2 and Lu Ni_2B_2 C with highly anisotropic gap. Such a field dependence of κ_0/T is an evidence for the multiple superconducting gaps with quite different magnitudes or highly anisotropic gap. Compared with the London penetration depth results of the Ca10(Pt_(4-δ)As_8)((Fe_(1-x)Pt_x)_2As_2)_5("10-3-8") compound, the 10-4-8 and 10-3-8 compounds may have a similar superconducting gap structure.
基金Project supported by the Shanghai Rising-Star Program(No.14QB1402800)
文摘Direct wafer bonding technology is able to integrate two smooth wafers and thus can be used in fab- ricating III-V multijunction solar cells with lattice mismatch. In order to monolithically interconnect between the GalnP/GaAs and InGaAsP/InGaAs subcells, the bonded GaAs/InP heterojunction must be a highly conductive ohmic junction or a tunnel junction. Three types of bonding interfaces were designed by tuning the conduction type and doping elements of GaAs and InP. The electrical properties of p-GaAs (Zn doped)/n-InP (Si doped), p- GaAs (C doped)/n-InP (Si doped) and n-GaAs (Si doped)/n-InP (Si doped) bonded heterojunctions were analyzed from the I-V characteristics. The wafer bonding process was investigated by improving the quality of the sample surface and optimizing the bonding parameters such as bonding temperature, bonding pressure, bonding time and so on. Finally, GalnP/GaAs/InGaAsP/lnGaAs 4-junction solar cells have been prepared by a direct wafer bonding technique with the high efficiency of 34.14% at the AM0 condition (1 Sun).