Developing new functional explosives that display high stability,good energy performance,and low sensitivity are one of the key directions of energetic materials research.In this work,two-dimensional(2D)Schiff-based e...Developing new functional explosives that display high stability,good energy performance,and low sensitivity are one of the key directions of energetic materials research.In this work,two-dimensional(2D)Schiff-based energetic covalent organic frameworks(COFs)are prepared based on triaminoguanidine salts with different anions as building blocks.Benefiting from the robust covalent bond in 2D extended polygons and strongπ-πinteractions in the eclipsed interlayers,the synthesized energetic COFs showed higher thermal stability and lower mechanical sensitivity than their precursor salts.More importantly,incorporating triaminoguanidine salts into COFs effectively increase the corrosion resistance to metal under high humidity conditions,which is due to the imine moieties in COFs functioning asπacceptors and offering strong bonding with metallic ions.This work provides a new pathway for the development of high-performance energetic materials.展开更多
Two 3d-4f heterometallic one-dimensional chains with neutral 4,4＇-bipyridine ligands as linkers and[Cu2Ln2] clusters （Ln = Gd for 1, Dy for 2） as nodes have been hydrothermally synthesized and structurally characte...Two 3d-4f heterometallic one-dimensional chains with neutral 4,4＇-bipyridine ligands as linkers and[Cu2Ln2] clusters （Ln = Gd for 1, Dy for 2） as nodes have been hydrothermally synthesized and structurally characterized. Magnetic studies indicate that complex 1 exhibits a relatively large magnetocaloric effect, with an entropy change -△Smax m= 24.8 J kg 1 K^-1, whilst, complex 2 features slow magnetic relaxation at low temperature.展开更多
Organometallic halide perovskite materials make great achievements in optoelectronic fields,especially in solar cells,in which the organic cations contain amine components.However,the amine with NàH bonds is easi...Organometallic halide perovskite materials make great achievements in optoelectronic fields,especially in solar cells,in which the organic cations contain amine components.However,the amine with NàH bonds is easily hydrolyzed with moisture in the air,weakening the perovskite materials stability.It is desirable to develop other non-amine stable perovskite materials.In this work,sulfur-based perovskite-like(CH_(3))_(3)SPbI_(3) nanorod arrays were fabricated by a solution-processed method,which can be indexed hexagonal crystal structure in the space group P63 mc.The binding force is exceptionally strong between the non-amine(CH_(3))_(3) S+and[PbI_(6)]_(4)-octahedral,leading to high stability of(CH_(3))_(3)SPbI_(3).The(CH_(3))_(3)SPbI_(3) nanorod arrays can keep the morphology and crystal structure in an ambient atmosphere over 60 days.In addition,the(CH_(3))_(3)SPbI_(3) nanorod arrays can offer direct charge transfer channels,which show excellent optoelectronic properties.The(CH_(3))_(3)SPbI_(3) nanorod arrays-based solar cells with VOx hole transfer layers achieved a power conversion efficiency of 2.07%with negligible hysteresis.And the(CH_(3))_(3)SPbI_(3) nanorod arrays were also effectively applied in photodetectors with interdigitated gold electrodes.This work demonstrates that sulfur-based perovskite-like(CH_(3))_(3)SPbI_(3) is a novel promising stable compound with great potential for practical optoelectronic applications.展开更多
Electromagnetic interference(EMI)shielding at Terahertz(THz)frequency range attracts increasing attention due to the rapid development of THz science and technologies.EMI shielding materials with small thickness,high ...Electromagnetic interference(EMI)shielding at Terahertz(THz)frequency range attracts increasing attention due to the rapid development of THz science and technologies.EMI shielding materials with small thickness,high shielding effectiveness(SE),good flexibility and stability are highly desirable.Herein,an ultrathin flexible copper/graphene(Cu/Gr)nanolayered composite are prepared,which can reach the average EMI SE of 60.95 dB at 0.1–1.0 THz with a thickness of only 160 nm,indicating that more than 99.9999%of the THz wave power can be shielded.Furthermore,the Cu/Gr nanolayered composite also exhibits excellent oxidation resistance,with a 93.09%maintenance rate for EMI SE value after heating at 120℃for 3 h in air,far higher than that of the bare Cu film(62.15%).Besides,the Cu/Gr nanolayered composite exhibits good mechanical flexibility and flexural fatigue resistance.The EMI SE value of the Cu/Gr nanolayered composite shows a maintenance rate of 98.87%even after 1500 times bending cycles,obviously higher than that of multilayer Cu film(93.07%).These results demonstrate that the ultrathin flexible Cu/Gr nanolayered composites with excellent shielding performance and good stability have a broad application prospect in THz shielding for wearable devices and next generation mobile communication equipment.展开更多
The polyoxometalate（POM）-imidazole ionic liquid（IL） [C8mim]2[Mo6O19]（C8mim=1-methyl-3-octylimi- dazolium） with a low melting point of 82.6 °C was successfully prepared and characterized by FTIR, XPS, NMR, T...The polyoxometalate（POM）-imidazole ionic liquid（IL） [C8mim]2[Mo6O19]（C8mim=1-methyl-3-octylimi- dazolium） with a low melting point of 82.6 °C was successfully prepared and characterized by FTIR, XPS, NMR, TG and so on. The polyoxomolybdate-based IL has high stability, and its decomposing temperature reaches 321 °C, which is higher than that of 1-alkyl-3-methylimidazolium halides IL. Further photocatalytic performances of the IL were measured via degrading dye rhodamine B（RB） in aqueous solution under the UV light irradiation. The experiments show that the conversion of RB reaches 80.5% after 90 min under UV-light and the degradation efficiency depends on the pH value of the solution, irradiation time and the dosage of the IL and so on.展开更多
As an alternative of Internet protocol(IP)multicast,application layer multicast(ALM)is widely used with the advantage of simplicity and flexibility.However,the existing problems of large transmission delay and poor st...As an alternative of Internet protocol(IP)multicast,application layer multicast(ALM)is widely used with the advantage of simplicity and flexibility.However,the existing problems of large transmission delay and poor stability limit the application and development.In this article,to solve these problems,an ALM model based on node potential(NP)and topological index(TI)is proposed.The proposed model considers the factors of node capability and node distance in constructing and maintaining multicast tree to reduce transmission delay and increase stability,and thus it improves the application level in real-time multimedia multicast.The computer simulations prove that the proposed model reduces the ALM transmission delay,increases multicast tree stability effectively,and improves the ALM performance,and therefore it is suitable to apply in large-scale real-time multimedia environment.展开更多
A new Ag/AgCl sensor for measuring marine electric fields was prepared and characterized through electrochemical methods and scanning electron microscopy.Its performance was evaluated in both laboratory and deep-water...A new Ag/AgCl sensor for measuring marine electric fields was prepared and characterized through electrochemical methods and scanning electron microscopy.Its performance was evaluated in both laboratory and deep-water settings.The study indicates that the double-pulse electrodeposition method is advantageous for producing Ag/AgCl sensors that maintain excellent stability over time.During a 20-day continuous stability test,the potential difference of the sensor consistently remained between -24.76μV and 62.07μV,with a minimum potential difference drift of 2.77μV per 24 h.All sensors accurately detected artificial signals in both the time and frequency domains,and their responses were consistent with one another.The minimum noise level of the sensor was 0.59 nV(√Hz)^(-1)@1 Hz.The sensor performed well in high-precision electric field measurements at a depth of approximately 2800 m in the South China Sea.The high stability and low noise level of the sensor make it an effective tool for detecting electrical conductivity structures beneath the seafloor.展开更多
Creating adsorption sites by doping heteroatoms into the graphitic structures of carbon electrodes is an effective strategy for improving lithium storage in lithium-ion batteries.In this work,we prepared carbon nanotu...Creating adsorption sites by doping heteroatoms into the graphitic structures of carbon electrodes is an effective strategy for improving lithium storage in lithium-ion batteries.In this work,we prepared carbon nanotubes with controllable morphology and controllable nitrogen-doping level by a one-step pyrolysis method through adjusting the amount of urea used during synthesis.Under the synergistic effects of high temperature and Ni-catalyst migration,the carbon nanosheets generated by pyrolysis become coiled into tube-like structures.Characterization using Raman and x-ray photoelectron spectroscopy revealed that the B and N atoms were successfully co-doped into the resultant carbon nanotubes.When the obtained materials were used as lithium-ion battery anodes,reversible specific capacities of 337.11 and 187.62 mA h g^(−1) were achieved at current densities of 100 and 2000 mA g^(−1),respectively.Moreover,a capacity of 140.53 mA h g^(−1) was retained after 2000 cycles at a current density of 2000 mA g^(−1).The mechanism of lithium storage in these carbon materials was elucidated using cyclic voltammetry tests.Regarding other functional applications,the synthesized composite carbon nanotube material could also be used in other energy-storage battery systems,such as in the sulfur-carrying structures of lithium-sulfur batteries and in the three-dimensional porous structures of sodium batteries.展开更多
Metal halide perovskite nanocrystals(MHP NCs)are of great candidates in photocatalytic applications due to their extreme light utilization efficiency.However,the instability towards humid environment severely restrict...Metal halide perovskite nanocrystals(MHP NCs)are of great candidates in photocatalytic applications due to their extreme light utilization efficiency.However,the instability towards humid environment severely restrict their practical application.Herein,the CsPbBr_(3)/CsPb_(2)Br_(5)heteronanocrystals(HNCs)were successfully encapsulated into ZIF-8 through a thermal injection method via controlling the molar ratio of Cs^(+)/Pb2^(+).The surface of ZIF-8 was then modified with hydrophobic copolymer of poly(methyl methacrylate)(PMMA)to improve the water stability.Benefiting from the intimate interfacial interaction and staggered energy band structure,the type-II heterojunction of CsPb Br_(3)/CsPb_(2)Br_(5)guarantees efficient separation and migration of photogenerated electron/hole pairs.Meanwhile,the formation of Z-scheme heterojunction between ZIF-8 and CsPbBr_(3)/CsPb_(2)Br_(5)HNCs contributes to the adsorption and enrichment of pollutants,further accelerates the photocatalytic antibiotic degradation efficiency towards tetracycline hydrochloride(TCH)in aqueous solution.Nearly 87%of TCH(40 mg/L,50 mL)was degraded by 40 mg catalyst within 100 min.This work offers a feasible approach in assembling high-performance MHP NCsbased efficient photocatalyst with expanding application in aqueous solution.展开更多
Polyphosphazene with phenoxy or 4-ester phenoxy as pendent groups are demonstrated as both ligands and host matrices for CsPbBr_(3) perovskite nanocrystals(NCs). These polymers produced fiexible nanocomposite films wi...Polyphosphazene with phenoxy or 4-ester phenoxy as pendent groups are demonstrated as both ligands and host matrices for CsPbBr_(3) perovskite nanocrystals(NCs). These polymers produced fiexible nanocomposite films with excellent NCs dispersion, optical transparency and stability in various extreme conditions. Both films remained stable even after 30 days of air storage. CsPbBr_(3) /poly[bis(phenoxy phosphazene)](PBPP) delivered better air and light stability, and CsPbBr_(3) /poly[bis(4-esterphenoxy)phosphazene](PBEPP) exhibited superior water and heat resistance. CsPbBr_(3) /PBEPP showed a greater increase in fiuorescence intensity under 365 nm UV light and demonstrated a 10% luminescence increase after 96 h of water immersion and even at high temperature(150℃). These findings thus provide new insight into fiexible luminescent CsPbBr_(3) films with high stability in optoelectronic applications.展开更多
Lead-free hybrid double perovskites(LFHDPs) have received a lot of attention due to their environmental friendliness and promising attributes. However, studying the effect of film thickness on LFHDPs optoelectronic pr...Lead-free hybrid double perovskites(LFHDPs) have received a lot of attention due to their environmental friendliness and promising attributes. However, studying the effect of film thickness on LFHDPs optoelectronic properties has not yet been investigated. Herein, we synthesized two new Ruddlesden–Popper LFHDPs, namely(C_(5)H_(12)N)_(4)AgBiI_(8)(CAB-1) and(C_(6)H_(14)N)_(4)Ag Bi I8(CAB-2) using cyclopentylamine and cyclohexylamine as monoamine ligands. Indeed, these two Ag(Ⅰ)-Bi(Ⅲ) LFHDPs form smooth and uniform films ranging in thickness from 250 nm to 1 μm, with preferred orientations. Notably, the studies on the optical properties showed that the direct band gap value decreased from 2.17 e V to 1.91 e V for CAB-1 and from 2.05 e V to 1.86 e V for CAB-2 with increasing thickness. Accordingly, photo-current response using a xenon lamp revealed a significant difference of over 1000 n A between light and dark conditions for1 μm-thickness films, suggesting potential for light harvesting. Other than that, thicker films of CAB-1and CAB-2 exhibit high stability for 90 days in a relatively humid environment(RH of 55%), paving the way for promising optoelectronic applications.展开更多
In order to analyze the influence of the addition of yttrium and manganese on the soot combustion performance and high temperature stability of CeO_(2) catalyst,a series of Y/Mn-modified CeO_(2) catalysts were prepare...In order to analyze the influence of the addition of yttrium and manganese on the soot combustion performance and high temperature stability of CeO_(2) catalyst,a series of Y/Mn-modified CeO_(2) catalysts were prepared.The effects of structural properties,textural properties,oxygen vacancies,Ce^(3+),surface adsorbed oxygen species,reduction properties and desorption properties of oxygen species on the activity were analyzed by various characterization methods.The results of the activity test show that the addition of manganese is beneficial to enhancement of the activity,while the addition of yttrium increases the amount of reactive oxygen species,but decreases the activity.After aging at 700℃,the activity of the CeMn catalyst decreases most sharply,while the catalytic activity of the CeY catalyst can be maintained to a certain extent.Interestingly,the addition of yttrium and manganese at the same time can stabilize the activity.The fundamental reason is that yttrium and manganese move to the surface of the solid solution after aging,which increases the reduction performance of the catalyst,thus contributing to the increase of activity.Although the activity of CeYMn catalyst decreases after aging at 800℃,it is still higher than that of other catalysts aged at 700℃.展开更多
Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage p...Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.展开更多
Quasi-solid-state composite electrolytes(QSCEs)show promise for high-performance solid-state batteries,while they still struggle with interfacial stability and cycling performance.Herein,a F-grafted QSCE(F-QSCE)was de...Quasi-solid-state composite electrolytes(QSCEs)show promise for high-performance solid-state batteries,while they still struggle with interfacial stability and cycling performance.Herein,a F-grafted QSCE(F-QSCE)was developed via copolymerizing the F monomers and ionic liquid monomers.The F-QSCE demonstrates better overall performance,such as high ionic conductivity of 1.21 mS cm^(-1)at 25℃,wide electrochemical windows of 5.20 V,and stable cycling stability for Li//Li symmetric cells over 4000 h.This is attributed to the significant electronegativity difference between C and F in the fluorinated chain(-CF_(2)-CF-CF_(3)),which causes the electron cloud to shift toward the F atom,surrounding it with a negative charge and producing the inductive effect.Furthermore,the interactions between Li^(+)and F,TFSI~-,and C are enhanced,reducing ion pair aggregation(Li^(+)-TFSI~--Li^(+))and promoting Li^(+)transport.Besides,-CF_(2)-CF-CF_(3)decomposes to form Li F preferentially over TFSI~-,resulting in better interfacial stability for F-QSCE.This work provides a pathway to enable the development of high-performance Li metal batteries.展开更多
Vanadium flow batteries(VFB)offer an ideal solution to the issue of storing massive amounts of electricity produced from intermittent renewables.However,the historical challenge of high thermal precipitation of V_(2)O...Vanadium flow batteries(VFB)offer an ideal solution to the issue of storing massive amounts of electricity produced from intermittent renewables.However,the historical challenge of high thermal precipitation of V_(2)O_(5)from VO_(2)^(+)(~50℃for 1 day)represents a critical concern.Temperature control can alleviate the problem to a certain extent,however,at the expense of the cost of system design and operation.Herein,we report stable electrolyte chemistry at high temperature.By introducing Cr^(3+)as a stabilizer,it bridges with VO_(2)^(+)to form a Cr—O—V^(Ⅴ)structure,which reduces the electron cloud density of V.Therefore,it combines more tightly with H_(2)O and prevents its dehydration process.In addition,the dimerization process of VO_(2)^(+)is also inhibited due to the occupancy of Cr^(3+).As a result,a formed 1.5 M VO_(2)^(+)electrolyte demonstrates a high stability for over 30 days at 50℃(v.s.blank for<1 day at 50℃).Additionally,the low-temperature precipitation temperature of V^(2+)on the negative side has been reduced from 0℃of commercial electrolytes to-5℃.As a proof of concept,a VFB assembled with Nafion 115 membrane demonstrates an energy efficiency(EE)of 80%at 120 mA cm^(-2)for 1000 cycles(50℃).Most importantly,a 4 kW stack can continuously run for~1000 cycles with EE of 80%at 120 mA cm^(-2)without any heat management.Combined with high thermal stability and excellent performance,our design will certainly provide new impetus for the further commercialization of VFB batteries.展开更多
We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd：YAG in a straight piano-concave cavity. The temperature distribution in composite cera...We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd：YAG in a straight piano-concave cavity. The temperature distribution in composite ceramic Nd：YAG crystal is numerically analyzed and compared with that of conventional Nd：YAG crystal. By using a composite ceramic Nd：YAG rod and a type-II high gray track resistance KTP （HGTR-KTP） crystal, a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz, with a diode-to-green optical conversion of 14.68%, and a pulse width of 162 ns. To the best of our knowledge, both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd：YAG laser to date. The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.展开更多
Flexible electromagnetic interference(EMI)shielding films with high stability have shown promising prospect in harsh working conditions such as military,communication,and special protection fields.Herein,flexible aram...Flexible electromagnetic interference(EMI)shielding films with high stability have shown promising prospect in harsh working conditions such as military,communication,and special protection fields.Herein,flexible aramid nanofibers@polypyrrole(ANF@PPy)films with high stability were easily achieved by the in-situ growth of PPy on the surface of ANF and the subsequent pressured-filtration film-forming process.When the amount of pyrrole(Py)monomer is 40μL,the ANF@PPy(AP40)film exhibited excellent EMI shielding performance with shielding effectiveness(SE)of 41.69 dB,tensile strength of 96.01 MPa,and fracture strain of 21.95%at the thickness of 75.76μm.Particularly,the anticipated EMI shielding performance can be maintained even after being heated at 200℃in air,soaked in 3.5%NaCl solution,repeated folding for one million times,or burned directly,indicating superior environmental durability in harsh conditions.Therefore,it is believed that the ANF@PPy films with high stability offer a facile solution for practical protection for high-performance EMI shielding applications.展开更多
Metal-nitrogen-carbon materials(M-N-C) are non-noble-metal-based alternatives to platinum-based catalysts and have attracted tremendous attention due to their low-cost,high abundance,and efficient catalytic performanc...Metal-nitrogen-carbon materials(M-N-C) are non-noble-metal-based alternatives to platinum-based catalysts and have attracted tremendous attention due to their low-cost,high abundance,and efficient catalytic performance towards the oxygen reduction reaction(ORR).Among them,Fe-based materials show remarkable ORR activity,but they are limited by low selectivity and low stability.To address these issues,herein,we have synthesized FeCu-based M-N-C catalysts,inspired by the bimetal center of cytochrome c oxidase(CcO).In acidic media,the selectivity was notably improved compared with Febased materials,with peroxide yields less than 1.2%(<1/3 of the hydrogen peroxide yields of Fe-N-C catalysts).In addition to Cu-N-C catalysts which can catalytically reduce hydrogen peroxide,the reduction current of hydrogen peroxide using FeCu-N-C-20 exceeded that of Fe-N-C by about 6% when the potential was greater than 0.4 V.Furthermore,FeCu-based M-N-C catalysts suffered from only a15 mV attenuation in their half-wave potentials after 10,000 cycles of accelerated degradation tests(ADT),while there was a 30 mV negative shift for Fe-N-C.Therefore,we propose that the H_(2)O_(2) released from Fe-Nx sites or N-doped carbon sites would be reduced by adjacent Cu-Nx sites,re sulting in low H_(2)O_(2) yields and high stability.展开更多
Purpose The high energy photon source(HEPS)uses the on-axial injection scheme.There are two designs in this injection scheme that are critical to the performance of the HEPS injection system.One is the strip line kick...Purpose The high energy photon source(HEPS)uses the on-axial injection scheme.There are two designs in this injection scheme that are critical to the performance of the HEPS injection system.One is the strip line kicker and another is the high voltage fast pulse power supply system.In the high voltage fast pulse power supply system,the design of high voltage power supply is very important.The output voltage stability of high voltage power supply directly affects the stability of the pulse amplitude of the injection system.Methods A high voltage power supply with high output voltage stability is designed in this paper,and the scheme is given.The correctness of the design scheme is verified by simulation experiments.Result A prototype is built for full test.The test results showed that the output voltage stability is lower than 58 ppm.The output voltage is 6.4 mV(f≤3 kHz)/113.2 mV(f>3 kHz).Conclusions The designed high voltage power supply can fully meet the requirements of the HEPS injection system.展开更多
We demonstrate a new technique to generate a high stability multi-wavelength fiber source by inserting a synchronized etalon filter in superfluorescent fiber source. Multi-wavelength source can easily be obtained over...We demonstrate a new technique to generate a high stability multi-wavelength fiber source by inserting a synchronized etalon filter in superfluorescent fiber source. Multi-wavelength source can easily be obtained over the EDF gain region with the proposed schedule. By partially feedback diffracted spontaneous emission into erbium doped fiber medium, greater output power, extinction ration and narrower linewidth for each channel than that simply using the spectrum slicing technique is easy obtained. Stab...展开更多
基金supported the National Natural Science Foundation of China(Nos.22175155,21825106 and 22275168)the Henan Science Fund for Excellent Young Scholars(No.212300410084)the opening project of State Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)(No.KFJJ22–05 M)。
文摘Developing new functional explosives that display high stability,good energy performance,and low sensitivity are one of the key directions of energetic materials research.In this work,two-dimensional(2D)Schiff-based energetic covalent organic frameworks(COFs)are prepared based on triaminoguanidine salts with different anions as building blocks.Benefiting from the robust covalent bond in 2D extended polygons and strongπ-πinteractions in the eclipsed interlayers,the synthesized energetic COFs showed higher thermal stability and lower mechanical sensitivity than their precursor salts.More importantly,incorporating triaminoguanidine salts into COFs effectively increase the corrosion resistance to metal under high humidity conditions,which is due to the imine moieties in COFs functioning asπacceptors and offering strong bonding with metallic ions.This work provides a new pathway for the development of high-performance energetic materials.
基金financially supported by the 973 Program of China(Nos.2012CB821700 and 2014CB845600)the NNSF of China(Nos.21031002 and 21290171)MOE Innovation Team (No.IRT13022) of China
文摘Two 3d-4f heterometallic one-dimensional chains with neutral 4,4＇-bipyridine ligands as linkers and[Cu2Ln2] clusters （Ln = Gd for 1, Dy for 2） as nodes have been hydrothermally synthesized and structurally characterized. Magnetic studies indicate that complex 1 exhibits a relatively large magnetocaloric effect, with an entropy change -△Smax m= 24.8 J kg 1 K^-1, whilst, complex 2 features slow magnetic relaxation at low temperature.
基金the financial support from the National Natural Science Foundation of China(U1732126,11804166,51602161,51372119)the Natural Science Foundation of Jiangsu Province(BK20150860)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX180846,KYCX180869)。
文摘Organometallic halide perovskite materials make great achievements in optoelectronic fields,especially in solar cells,in which the organic cations contain amine components.However,the amine with NàH bonds is easily hydrolyzed with moisture in the air,weakening the perovskite materials stability.It is desirable to develop other non-amine stable perovskite materials.In this work,sulfur-based perovskite-like(CH_(3))_(3)SPbI_(3) nanorod arrays were fabricated by a solution-processed method,which can be indexed hexagonal crystal structure in the space group P63 mc.The binding force is exceptionally strong between the non-amine(CH_(3))_(3) S+and[PbI_(6)]_(4)-octahedral,leading to high stability of(CH_(3))_(3)SPbI_(3).The(CH_(3))_(3)SPbI_(3) nanorod arrays can keep the morphology and crystal structure in an ambient atmosphere over 60 days.In addition,the(CH_(3))_(3)SPbI_(3) nanorod arrays can offer direct charge transfer channels,which show excellent optoelectronic properties.The(CH_(3))_(3)SPbI_(3) nanorod arrays-based solar cells with VOx hole transfer layers achieved a power conversion efficiency of 2.07%with negligible hysteresis.And the(CH_(3))_(3)SPbI_(3) nanorod arrays were also effectively applied in photodetectors with interdigitated gold electrodes.This work demonstrates that sulfur-based perovskite-like(CH_(3))_(3)SPbI_(3) is a novel promising stable compound with great potential for practical optoelectronic applications.
基金supported financially by the Foundation of Ministry of Science and Technology of China(No.2016YFA0200200)the National Natural Science Foundation of China(Nos.21875114,51373078 and 51422304)111 Project(No.B18030)。
文摘Electromagnetic interference(EMI)shielding at Terahertz(THz)frequency range attracts increasing attention due to the rapid development of THz science and technologies.EMI shielding materials with small thickness,high shielding effectiveness(SE),good flexibility and stability are highly desirable.Herein,an ultrathin flexible copper/graphene(Cu/Gr)nanolayered composite are prepared,which can reach the average EMI SE of 60.95 dB at 0.1–1.0 THz with a thickness of only 160 nm,indicating that more than 99.9999%of the THz wave power can be shielded.Furthermore,the Cu/Gr nanolayered composite also exhibits excellent oxidation resistance,with a 93.09%maintenance rate for EMI SE value after heating at 120℃for 3 h in air,far higher than that of the bare Cu film(62.15%).Besides,the Cu/Gr nanolayered composite exhibits good mechanical flexibility and flexural fatigue resistance.The EMI SE value of the Cu/Gr nanolayered composite shows a maintenance rate of 98.87%even after 1500 times bending cycles,obviously higher than that of multilayer Cu film(93.07%).These results demonstrate that the ultrathin flexible Cu/Gr nanolayered composites with excellent shielding performance and good stability have a broad application prospect in THz shielding for wearable devices and next generation mobile communication equipment.
基金Supported by the National Natural Science Foundation of China(Nos.2067101120731002+3 种基金20801004 10876002 20801005)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.200800070015).
文摘The polyoxometalate（POM）-imidazole ionic liquid（IL） [C8mim]2[Mo6O19]（C8mim=1-methyl-3-octylimi- dazolium） with a low melting point of 82.6 °C was successfully prepared and characterized by FTIR, XPS, NMR, TG and so on. The polyoxomolybdate-based IL has high stability, and its decomposing temperature reaches 321 °C, which is higher than that of 1-alkyl-3-methylimidazolium halides IL. Further photocatalytic performances of the IL were measured via degrading dye rhodamine B（RB） in aqueous solution under the UV light irradiation. The experiments show that the conversion of RB reaches 80.5% after 90 min under UV-light and the degradation efficiency depends on the pH value of the solution, irradiation time and the dosage of the IL and so on.
基金National Natural Science Foundation of China(Nos.71171045 and 61801107)。
文摘As an alternative of Internet protocol(IP)multicast,application layer multicast(ALM)is widely used with the advantage of simplicity and flexibility.However,the existing problems of large transmission delay and poor stability limit the application and development.In this article,to solve these problems,an ALM model based on node potential(NP)and topological index(TI)is proposed.The proposed model considers the factors of node capability and node distance in constructing and maintaining multicast tree to reduce transmission delay and increase stability,and thus it improves the application level in real-time multimedia multicast.The computer simulations prove that the proposed model reduces the ALM transmission delay,increases multicast tree stability effectively,and improves the ALM performance,and therefore it is suitable to apply in large-scale real-time multimedia environment.
基金supported by the National Natural Science Foundation of China(Nos.U23B20158,91958210,42004055)。
文摘A new Ag/AgCl sensor for measuring marine electric fields was prepared and characterized through electrochemical methods and scanning electron microscopy.Its performance was evaluated in both laboratory and deep-water settings.The study indicates that the double-pulse electrodeposition method is advantageous for producing Ag/AgCl sensors that maintain excellent stability over time.During a 20-day continuous stability test,the potential difference of the sensor consistently remained between -24.76μV and 62.07μV,with a minimum potential difference drift of 2.77μV per 24 h.All sensors accurately detected artificial signals in both the time and frequency domains,and their responses were consistent with one another.The minimum noise level of the sensor was 0.59 nV(√Hz)^(-1)@1 Hz.The sensor performed well in high-precision electric field measurements at a depth of approximately 2800 m in the South China Sea.The high stability and low noise level of the sensor make it an effective tool for detecting electrical conductivity structures beneath the seafloor.
文摘Creating adsorption sites by doping heteroatoms into the graphitic structures of carbon electrodes is an effective strategy for improving lithium storage in lithium-ion batteries.In this work,we prepared carbon nanotubes with controllable morphology and controllable nitrogen-doping level by a one-step pyrolysis method through adjusting the amount of urea used during synthesis.Under the synergistic effects of high temperature and Ni-catalyst migration,the carbon nanosheets generated by pyrolysis become coiled into tube-like structures.Characterization using Raman and x-ray photoelectron spectroscopy revealed that the B and N atoms were successfully co-doped into the resultant carbon nanotubes.When the obtained materials were used as lithium-ion battery anodes,reversible specific capacities of 337.11 and 187.62 mA h g^(−1) were achieved at current densities of 100 and 2000 mA g^(−1),respectively.Moreover,a capacity of 140.53 mA h g^(−1) was retained after 2000 cycles at a current density of 2000 mA g^(−1).The mechanism of lithium storage in these carbon materials was elucidated using cyclic voltammetry tests.Regarding other functional applications,the synthesized composite carbon nanotube material could also be used in other energy-storage battery systems,such as in the sulfur-carrying structures of lithium-sulfur batteries and in the three-dimensional porous structures of sodium batteries.
基金supported by National Natural Science Foundation of China(No.22171040)Shenyang Young and Middle-aged Science and Technology Innovation Talent Support Program(No.RC230784)+1 种基金Guangdong Basic and Applied Basic Research Foundation(No.2023A1515140011)Fundamental Research Funds for the Central Universities,China(No.N2305017)。
文摘Metal halide perovskite nanocrystals(MHP NCs)are of great candidates in photocatalytic applications due to their extreme light utilization efficiency.However,the instability towards humid environment severely restrict their practical application.Herein,the CsPbBr_(3)/CsPb_(2)Br_(5)heteronanocrystals(HNCs)were successfully encapsulated into ZIF-8 through a thermal injection method via controlling the molar ratio of Cs^(+)/Pb2^(+).The surface of ZIF-8 was then modified with hydrophobic copolymer of poly(methyl methacrylate)(PMMA)to improve the water stability.Benefiting from the intimate interfacial interaction and staggered energy band structure,the type-II heterojunction of CsPb Br_(3)/CsPb_(2)Br_(5)guarantees efficient separation and migration of photogenerated electron/hole pairs.Meanwhile,the formation of Z-scheme heterojunction between ZIF-8 and CsPbBr_(3)/CsPb_(2)Br_(5)HNCs contributes to the adsorption and enrichment of pollutants,further accelerates the photocatalytic antibiotic degradation efficiency towards tetracycline hydrochloride(TCH)in aqueous solution.Nearly 87%of TCH(40 mg/L,50 mL)was degraded by 40 mg catalyst within 100 min.This work offers a feasible approach in assembling high-performance MHP NCsbased efficient photocatalyst with expanding application in aqueous solution.
基金supported by the National Science Foundation (NSF) of China (No. 51773010)the Weifang Science and Technology Development Plan Program (No. 2023GX005)。
文摘Polyphosphazene with phenoxy or 4-ester phenoxy as pendent groups are demonstrated as both ligands and host matrices for CsPbBr_(3) perovskite nanocrystals(NCs). These polymers produced fiexible nanocomposite films with excellent NCs dispersion, optical transparency and stability in various extreme conditions. Both films remained stable even after 30 days of air storage. CsPbBr_(3) /poly[bis(phenoxy phosphazene)](PBPP) delivered better air and light stability, and CsPbBr_(3) /poly[bis(4-esterphenoxy)phosphazene](PBEPP) exhibited superior water and heat resistance. CsPbBr_(3) /PBEPP showed a greater increase in fiuorescence intensity under 365 nm UV light and demonstrated a 10% luminescence increase after 96 h of water immersion and even at high temperature(150℃). These findings thus provide new insight into fiexible luminescent CsPbBr_(3) films with high stability in optoelectronic applications.
基金supported by the National Natural Science Foundation of China (Nos. 22375157 and W2433042)the Key Scientific and Technological Innovation Team of Shaanxi Province(No. 2020TD-001)+1 种基金the Fundamental Research Funds for Central Universities, State Key Laboratory of Electrical Insulation and Power Equipment (No. EIPE23409)the Instrument Analysis Center of Xi’an Jiaotong University for assistance。
文摘Lead-free hybrid double perovskites(LFHDPs) have received a lot of attention due to their environmental friendliness and promising attributes. However, studying the effect of film thickness on LFHDPs optoelectronic properties has not yet been investigated. Herein, we synthesized two new Ruddlesden–Popper LFHDPs, namely(C_(5)H_(12)N)_(4)AgBiI_(8)(CAB-1) and(C_(6)H_(14)N)_(4)Ag Bi I8(CAB-2) using cyclopentylamine and cyclohexylamine as monoamine ligands. Indeed, these two Ag(Ⅰ)-Bi(Ⅲ) LFHDPs form smooth and uniform films ranging in thickness from 250 nm to 1 μm, with preferred orientations. Notably, the studies on the optical properties showed that the direct band gap value decreased from 2.17 e V to 1.91 e V for CAB-1 and from 2.05 e V to 1.86 e V for CAB-2 with increasing thickness. Accordingly, photo-current response using a xenon lamp revealed a significant difference of over 1000 n A between light and dark conditions for1 μm-thickness films, suggesting potential for light harvesting. Other than that, thicker films of CAB-1and CAB-2 exhibit high stability for 90 days in a relatively humid environment(RH of 55%), paving the way for promising optoelectronic applications.
基金Project supported by the National Natural Science Foundation of China(21962021)the Yunnan Fundamental Research Projects(202001AU070121)+1 种基金the National Natural Science Foundation of China(51908091)the Special Basic Cooperative Research Programs of Yunnan Provincial Undergraduate Universities'Association(202101BA070001-084)。
文摘In order to analyze the influence of the addition of yttrium and manganese on the soot combustion performance and high temperature stability of CeO_(2) catalyst,a series of Y/Mn-modified CeO_(2) catalysts were prepared.The effects of structural properties,textural properties,oxygen vacancies,Ce^(3+),surface adsorbed oxygen species,reduction properties and desorption properties of oxygen species on the activity were analyzed by various characterization methods.The results of the activity test show that the addition of manganese is beneficial to enhancement of the activity,while the addition of yttrium increases the amount of reactive oxygen species,but decreases the activity.After aging at 700℃,the activity of the CeMn catalyst decreases most sharply,while the catalytic activity of the CeY catalyst can be maintained to a certain extent.Interestingly,the addition of yttrium and manganese at the same time can stabilize the activity.The fundamental reason is that yttrium and manganese move to the surface of the solid solution after aging,which increases the reduction performance of the catalyst,thus contributing to the increase of activity.Although the activity of CeYMn catalyst decreases after aging at 800℃,it is still higher than that of other catalysts aged at 700℃.
基金supported by Fundamental Research Funds for the Central Universities(2023KYJD1008)the Science Research Projects of the Anhui Higher Education Institutions of China(2022AH051582).
文摘Reversible solid oxide cell(RSOC)is a new energy conversion device with significant applications,especially for power grid peaking shaving.However,the reversible conversion process of power generation/energy storage poses challenges for the performance and stability of air electrodes.In this work,a novel high-entropy perovskite oxide La_(0.2)Pr_(0.2)Gd_(0.2)Sm_(0.2)Sr_(0.2)Co_(0.8)Fe_(0.2)O_(3−δ)(HE-LSCF)is proposed and investigated as an air electrode in RSOC.The electrochemical behavior of HE-LSCF was studied as an air electrode in both fuel cell and electrolysis modes.The polarization impedance(Rp)of the HE-LSCF electrode is only 0.25Ω·cm^(2) at 800℃ in an air atmosphere.Notably,at an electrolytic voltage of 2 V and a temperature of 800℃,the current density reaches up to 1.68 A/cm^(2).The HE-LSCF air electrode exhibited excellent reversibility and stability,and its electrochemical performance remains stable after 100 h of reversible operation.With these advantages,HE-LSCF is shown to be an excellent air electrode for RSOC.
基金conducted in a project within M-ERA.NET 3 with support from the European Union’s Horizon 2020 research,innovation program under grant agreement No.958174,Vinnova(Swedish Governmental Agency for Innovation Systems)the financial support from the LTU CREATERNITY program+1 种基金the J.Gust Richert Foundationthe National Natural Science Foundation of China(No.U23A20122)。
文摘Quasi-solid-state composite electrolytes(QSCEs)show promise for high-performance solid-state batteries,while they still struggle with interfacial stability and cycling performance.Herein,a F-grafted QSCE(F-QSCE)was developed via copolymerizing the F monomers and ionic liquid monomers.The F-QSCE demonstrates better overall performance,such as high ionic conductivity of 1.21 mS cm^(-1)at 25℃,wide electrochemical windows of 5.20 V,and stable cycling stability for Li//Li symmetric cells over 4000 h.This is attributed to the significant electronegativity difference between C and F in the fluorinated chain(-CF_(2)-CF-CF_(3)),which causes the electron cloud to shift toward the F atom,surrounding it with a negative charge and producing the inductive effect.Furthermore,the interactions between Li^(+)and F,TFSI~-,and C are enhanced,reducing ion pair aggregation(Li^(+)-TFSI~--Li^(+))and promoting Li^(+)transport.Besides,-CF_(2)-CF-CF_(3)decomposes to form Li F preferentially over TFSI~-,resulting in better interfacial stability for F-QSCE.This work provides a pathway to enable the development of high-performance Li metal batteries.
基金financially supported by National Key R&D Program of China(2022YFB2404903)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0400201)+6 种基金International Partnership Program of Chinese Academy of Sciences(121421KYSB20210028)National Natural Science Foundation of China(22209179,22478379)Liaoning Provincial Natural Science Foundation(2023-MS-010)Science and Technology Major Project of Liaoning Province(2024JH1/11700011)International Science and Technology Cooperation program of Liaoning(2023JH2/10700002)Liaoning Bidding for Key Technology Project(2022JH1/10800038,2023JH1/10400065)Liaoning Binhai Laboratory Funding(LBLA-2022-02,LBLB-2023-01)。
文摘Vanadium flow batteries(VFB)offer an ideal solution to the issue of storing massive amounts of electricity produced from intermittent renewables.However,the historical challenge of high thermal precipitation of V_(2)O_(5)from VO_(2)^(+)(~50℃for 1 day)represents a critical concern.Temperature control can alleviate the problem to a certain extent,however,at the expense of the cost of system design and operation.Herein,we report stable electrolyte chemistry at high temperature.By introducing Cr^(3+)as a stabilizer,it bridges with VO_(2)^(+)to form a Cr—O—V^(Ⅴ)structure,which reduces the electron cloud density of V.Therefore,it combines more tightly with H_(2)O and prevents its dehydration process.In addition,the dimerization process of VO_(2)^(+)is also inhibited due to the occupancy of Cr^(3+).As a result,a formed 1.5 M VO_(2)^(+)electrolyte demonstrates a high stability for over 30 days at 50℃(v.s.blank for<1 day at 50℃).Additionally,the low-temperature precipitation temperature of V^(2+)on the negative side has been reduced from 0℃of commercial electrolytes to-5℃.As a proof of concept,a VFB assembled with Nafion 115 membrane demonstrates an energy efficiency(EE)of 80%at 120 mA cm^(-2)for 1000 cycles(50℃).Most importantly,a 4 kW stack can continuously run for~1000 cycles with EE of 80%at 120 mA cm^(-2)without any heat management.Combined with high thermal stability and excellent performance,our design will certainly provide new impetus for the further commercialization of VFB batteries.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 61107086, 61172010, and 61101058)the Science and Technology Committee of Tianjin, China (Grant No. 11JCYBJC01100)the National High Technology Research and Development Program of China (Grant No. 2011AA010205)
文摘We successfully obtain a high-average-power high-stability Q-switched green laser based on diode-side-pumped composite ceramic Nd：YAG in a straight piano-concave cavity. The temperature distribution in composite ceramic Nd：YAG crystal is numerically analyzed and compared with that of conventional Nd：YAG crystal. By using a composite ceramic Nd：YAG rod and a type-II high gray track resistance KTP （HGTR-KTP） crystal, a green laser with an average output power of 165 W is obtained at a repetition rate of 25 kHz, with a diode-to-green optical conversion of 14.68%, and a pulse width of 162 ns. To the best of our knowledge, both the output power and optical-to-optical efficiency are the highest values for green laser systems with intracavity frequency doubling of this novel composite ceramic Nd：YAG laser to date. The power fluctuation at around 160 W is lower than 0.3% in 2.5 hours.
基金the Science and Technology Commission of Shanghai Municipality(Nos.20230742300 and 18595800700)the project of“joint assignment”in Shanghai University led by Prof.
文摘Flexible electromagnetic interference(EMI)shielding films with high stability have shown promising prospect in harsh working conditions such as military,communication,and special protection fields.Herein,flexible aramid nanofibers@polypyrrole(ANF@PPy)films with high stability were easily achieved by the in-situ growth of PPy on the surface of ANF and the subsequent pressured-filtration film-forming process.When the amount of pyrrole(Py)monomer is 40μL,the ANF@PPy(AP40)film exhibited excellent EMI shielding performance with shielding effectiveness(SE)of 41.69 dB,tensile strength of 96.01 MPa,and fracture strain of 21.95%at the thickness of 75.76μm.Particularly,the anticipated EMI shielding performance can be maintained even after being heated at 200℃in air,soaked in 3.5%NaCl solution,repeated folding for one million times,or burned directly,indicating superior environmental durability in harsh conditions.Therefore,it is believed that the ANF@PPy films with high stability offer a facile solution for practical protection for high-performance EMI shielding applications.
基金the National Science and Technology Major Project(No.2017YFB0102900)the National Natural Science Foundation of China(Nos.21633008,21433003)+1 种基金the Jilin Province Science and Technology Development Program(No.20170203003SF)the Hundred Talents Program of the Chinese Academy of Sciences for financial support。
文摘Metal-nitrogen-carbon materials(M-N-C) are non-noble-metal-based alternatives to platinum-based catalysts and have attracted tremendous attention due to their low-cost,high abundance,and efficient catalytic performance towards the oxygen reduction reaction(ORR).Among them,Fe-based materials show remarkable ORR activity,but they are limited by low selectivity and low stability.To address these issues,herein,we have synthesized FeCu-based M-N-C catalysts,inspired by the bimetal center of cytochrome c oxidase(CcO).In acidic media,the selectivity was notably improved compared with Febased materials,with peroxide yields less than 1.2%(<1/3 of the hydrogen peroxide yields of Fe-N-C catalysts).In addition to Cu-N-C catalysts which can catalytically reduce hydrogen peroxide,the reduction current of hydrogen peroxide using FeCu-N-C-20 exceeded that of Fe-N-C by about 6% when the potential was greater than 0.4 V.Furthermore,FeCu-based M-N-C catalysts suffered from only a15 mV attenuation in their half-wave potentials after 10,000 cycles of accelerated degradation tests(ADT),while there was a 30 mV negative shift for Fe-N-C.Therefore,we propose that the H_(2)O_(2) released from Fe-Nx sites or N-doped carbon sites would be reduced by adjacent Cu-Nx sites,re sulting in low H_(2)O_(2) yields and high stability.
文摘Purpose The high energy photon source(HEPS)uses the on-axial injection scheme.There are two designs in this injection scheme that are critical to the performance of the HEPS injection system.One is the strip line kicker and another is the high voltage fast pulse power supply system.In the high voltage fast pulse power supply system,the design of high voltage power supply is very important.The output voltage stability of high voltage power supply directly affects the stability of the pulse amplitude of the injection system.Methods A high voltage power supply with high output voltage stability is designed in this paper,and the scheme is given.The correctness of the design scheme is verified by simulation experiments.Result A prototype is built for full test.The test results showed that the output voltage stability is lower than 58 ppm.The output voltage is 6.4 mV(f≤3 kHz)/113.2 mV(f>3 kHz).Conclusions The designed high voltage power supply can fully meet the requirements of the HEPS injection system.
文摘We demonstrate a new technique to generate a high stability multi-wavelength fiber source by inserting a synchronized etalon filter in superfluorescent fiber source. Multi-wavelength source can easily be obtained over the EDF gain region with the proposed schedule. By partially feedback diffracted spontaneous emission into erbium doped fiber medium, greater output power, extinction ration and narrower linewidth for each channel than that simply using the spectrum slicing technique is easy obtained. Stab...
