Although advanced anode materials for the lithium-ion battery have been investigated for decades,a reliable,high-capacity,and durable material that can enable a fast charge remains elusive.Herein,we report that a meta...Although advanced anode materials for the lithium-ion battery have been investigated for decades,a reliable,high-capacity,and durable material that can enable a fast charge remains elusive.Herein,we report that a metal phosphorous trichalcogenide of MnPS_(3)(manganese phosphorus trisulfide),endowed with a unique and layered van der Waals structure,is highly beneficial for the fast insertion/extraction of alkali metal ions and can facilitate changes in the buffer volume during cycles with robust structural stability.The few-layered MnPS_(3)anodes displayed the desirable specific capacity and excellent rate chargeability owing to their good electronic and ionic conductivities.When assembled as a half-cell lithium-ion battery,a high reversible capacity of 380 mA h g^(−1)was maintained by the MnPS_(3)after 3000 cycles at a high current density of 4 A g^(−1),with a capacity retention of close to or above 100%.In full-cell testing,a reversible capacity of 450 mA h g^(−1)after 200 cycles was maintained as well.The results of in-situ TEM revealed that MnPS_(3)nanoflakes maintained a high structural integrity without exhibiting any pulverization after undergoing large volumetric expansion for the insertion of a large number of lithium ions.Their kinetics of lithium-ion diffusion,stable structure,and high pseudocapacitance contributed to their comprehensive performance,for example,a high specific capacity,rapid charge-discharge,and long cyclability.MnPS_(3)is thus an efficient anode for the next generation of batteries with a fast charge/discharge capability.展开更多
The electrochemical performance of lithium-ion batteries,i.e.specific capacity and cyclability,is primarily determined by chemical reversibility and structural stability of the electrodes in cycling.Here we have inves...The electrochemical performance of lithium-ion batteries,i.e.specific capacity and cyclability,is primarily determined by chemical reversibility and structural stability of the electrodes in cycling.Here we have investigated the fundamental reaction behaviors of nickel sulfide(NixSy)as lithium-ion battery anodes by in-situ TEM.We find that Ni_(3)S_(2)is the electrochemically stable phase,which appears in the first cycle of the NixSyanode.From the second cycle,conversion between Ni_(3)S_(2)and Li_(2)S/Ni is the dominant electrochemical reaction.In lithiation,the NixSynanoparticles evolve into a mixture of Ni nanocrystals embedded in Li_(2)S matrix,which form a porous structure upon full lithiation,and with the recrystallization of the Ni_(3)S_(2)phase in delithiation,a compact and interconnected network is built.Structural stability in cycles is susceptible to particle size and substrate restraint.Carbon substrate can certainly improve the tolerance for size-dependent pulverization of NixSynanoparticles.When NixSynanoparticle exceeds the critical size value,the morphology of the particle is no longer well maintained even under the constraints of the carbon substrate.This work deepens the understanding of electrochemical reaction behavior of conversiontype materials and helps to rational design of high-energy density battery anodes.展开更多
An oil-based drilling fluid should be stable and tolerant to high temperatures for use in deep drilling. An invert emulsion of water in oil is a good choice as an oil- based drilling fluid which is a mixture of a soli...An oil-based drilling fluid should be stable and tolerant to high temperatures for use in deep drilling. An invert emulsion of water in oil is a good choice as an oil- based drilling fluid which is a mixture of a solid phase and two immiscible liquid phases stabilized by a polymeric surfactant. In deep drilling, due to high temperatures, the polymeric surfactant degrades and a phase separation occurs. Here, octadecyltrimethoxysilane-modified silica nanoparticles were used to form a stable invert emulsion of water in oil for the drilling fluid model which resulted in a milky fluid with the formation of 60 gm water droplets. In addition, rheological study showed that using hydrophobic silica nanoparticles resulted in a stable water in oil invert emulsion with desired properties for a drilling fluid that can be modified by adjusting the nanoparticle nature and content. Aging experiments at 120 ℃ indicated that they also have good stability at high temperatures for challenging drilling operations.展开更多
Transition metal-based layered double hydroxides(LDHs)have been capable of working efficiently as catalysts in the basic oxygen evolution reaction(OER)for sustaining hydrogen production of alkaline water electrolysis....Transition metal-based layered double hydroxides(LDHs)have been capable of working efficiently as catalysts in the basic oxygen evolution reaction(OER)for sustaining hydrogen production of alkaline water electrolysis.Nevertheless,exploring new LDH-based electrocatalysts featuring both remarkable activity and good stability is still in high demand,which is pivotal for comprehensive understanding and impressive improvement of the sluggish OER kinetics.Here,a series of bimetallic(Co and Mo)LDH arrays were designed and fabricated via a facile and controlled strategy by incorporating a Mo source into presynthesized Co-based metal-organic framework(MOF)arrays on carbon cloth(CC),named as ZIF-67/CC arrays.We found that tuning the Mo content resulted in gradual differences in the structural properties,surface morphology,and chemical states of the resulting catalysts,namely CoMox-LDH/CC(x representing the added weight of the Mo source).Gratifyingly,the best-performing CoMo_(0.20)-LDH/CC electrocatalyst demonstrates a low overpotential of only 226 mV and high stability at a current density of 10 mA·cm^(−2),which is superior to most LDH-based OER catalysts reported previously.Furthermore,it only required 1.611 V voltage to drive the overall water splitting device at the current density of 10 mA·cm^(−2).The present study represents a significant advancement in the development and applications of new OER catalysts.展开更多
Local phase transition in transition metal dichalcogenides (TMDCs) by lithiumintercalation enables the fabrication of high-quality contact interfaces in twodimensional(2D) electronic devices. However, controlling the ...Local phase transition in transition metal dichalcogenides (TMDCs) by lithiumintercalation enables the fabrication of high-quality contact interfaces in twodimensional(2D) electronic devices. However, controlling the intercalation oflithium is hitherto challenging in vertically stacked van der Waalsheterostructures (vdWHs) due to the random diffusion of lithium ions in thehetero-interface, which hinders their application for contact engineering of 2DvdWHs devices. Herein, a strategy to restrict the lithium intercalation pathwayin vdWHs is developed by using surface-permeation assisted intercalationwhile sealing all edges, based on which a high-performance edge-contact MoS_(2)vdWHs floating-gate transistor is demonstrated. Our method avoids intercalationfrom edges that are prone to be random but intentionally promotes lithiumintercalation from the top surface. The derived MoS_(2) floating-gatetransistor exhibits improved interface quality and significantly reduced subthresholdswing (SS) from >600 to 100 mV dec^(–1). In addition, ultrafast program/erase performance together with well-distinguished 32 memory statesare demonstrated, making it a promising candidate for low-power artificialsynapses. The study on controlling the lithium intercalation pathways in 2DvdWHs offers a viable route toward high-performance 2D electronics for memoryand neuromorphic computing purposes.展开更多
Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic ac...Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolyrner such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide （PA） domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.展开更多
单质硅是一种有潜力的高容量锂离子电池负极材料.然而,受限于充放电过程中巨大的体积膨胀,其循环性能并不理想.在这个工作中,我们设计了一种独特的三组分复合负极材料(Si/Cr_(2)O_(3)/C),其中Si纳米颗粒被限域在碳包覆的氧化铬多层空心...单质硅是一种有潜力的高容量锂离子电池负极材料.然而,受限于充放电过程中巨大的体积膨胀,其循环性能并不理想.在这个工作中,我们设计了一种独特的三组分复合负极材料(Si/Cr_(2)O_(3)/C),其中Si纳米颗粒被限域在碳包覆的氧化铬多层空心球(MSHSs)中.得益于Cr_(2)O_(3)/C基体的体积变化缓冲能力与优异的结构稳定性,将Si纳米颗粒封装在MSHSs中可以有效地提高其电化学性能.合理的结构设计赋予了Si/Cr_(2)O_(3)/C三组分复合材料高的可逆容量(在100 mA g^(-1)的电流密度下,比容量为1351 mA h g^(-1))和稳定的循环性能(在500 mA g^(-1)的电流密度下,循环300次后比容量保持在716 mA h g^(-1)).这一工作提出了一种多壳层空心结构设计的新思路,以解决硅基负极材料循环性差的瓶颈.展开更多
Transition metal oxides with layered structure have been widely used as cathode materials for lithium-ion batteries(LIBs)which have relatively high energy density,large capacity and long life.However,in the long-term ...Transition metal oxides with layered structure have been widely used as cathode materials for lithium-ion batteries(LIBs)which have relatively high energy density,large capacity and long life.However,in the long-term electrochemical cycle,the inevitable degradation of performance of LIBs due to structural degradation in cathodes severely restricts their large-scale practical applications.Understanding the underlying mechanism of structural degradation is the most critical scientific problem.Recently,in situ transmission electron microscopy(TEM)has become a useful tool to study the structural and compositional evolutions at atomic scale in electrochemical reactions,which provided a unique and in-depth understanding of the structural degradation.In this review,we discuss the recent advances in the in situ TEM,focusing on its role in revealing the structural degradation mechanisms in the four key places:(1)the interface between the cathodes and electrolyte;(2)the cathode surface;(3)the particle interior and(4)those induced by thermal effect.The insight gained by the in-situ TEM which is still developing at its fast pace is unique and expected to provide guidance for designing better layered cathode materials.展开更多
Developing efficient platinum-based electrocatalysts with super durability for the oxygen reduction reaction(ORR)is highly desirable to promote the large-scale commercialization of fuel cells.Although progress has bee...Developing efficient platinum-based electrocatalysts with super durability for the oxygen reduction reaction(ORR)is highly desirable to promote the large-scale commercialization of fuel cells.Although progress has been made in this aspect,the electrochemical kinetics and stability of platinum-based catalysts are still far from the requirements of the practical applications.Herein,PtPdFeCoNi high-entropy alloy(HEA)nanoparticles were demonstrated via a high-temperature injection method.PtPdFeCoNi HEA nanocatalyst exhibits outstanding catalytic activity and stability towards ORR due to the high entropy,lattice distortion,and sluggish diffusion effects of HEA,and the HEA nanoparticles delivered a mass activity of 1.23 A/mgPt and a specific activity of 1.80 mA/cmPt 2,which enhanced by 6.2 and 4.9 times,respectively,compared with the values of the commercial Pt/C catalyst.More importantly,the high durability of PtPdFeCoNi HEA/C was evidenced by only 6 mV negativeshifted half-wave potential after 50,000 cycles of accelerated durability test(ADT).展开更多
Lithium-sulfur(Li-S)batteries have attracted significant attention for their high specific capacity,non-toxic and harmless advantages.However,the shuttle effect limits their development.In this work,small-sized tin di...Lithium-sulfur(Li-S)batteries have attracted significant attention for their high specific capacity,non-toxic and harmless advantages.However,the shuttle effect limits their development.In this work,small-sized tin disulfide(SnS_(2))nanoparticles are embedded between interlayers of twodimensional porous carbon nanosheets(PCNs),forming a multi-functional nanocomposite(PCN-SnS_(2))as a cathode carrier for Li-S batteries.The graphitized carbon nanosheets improve the overall conductivity of the electrode,and the abundant pores not only facilitate ion transfer and electrolyte permeation,but also buffer the volume change during the charge and discharge process to ensure the integrity of the electrode material.More importantly,the physical confinement of PCN,as well as the strong chemical adsorption and catalytic reaction of small SnS_(2)nanoparticles,synergistically reduce the shuttle effect of polysulfides.The interaction between a porous layered structure and physical-chemical confinement gives the PCN-SnS_(2)-S electrode high electrochemical performance.Even at a high rate of 2 C,a discharge capacity of 650 mA h g^(-1)is maintained after 150 cycles,underscoring the positive results of SnS_(2)-based materials for Li-S batteries.The galvanostatic intermittent titration technique results further confirm that the PCN-SnS_(2)-S electrode has a high Li+transmission rate,which reduces the activation barrier and improves the electrochemical reaction kinetics.This work provides strong evidence that reducing the size of SnS_(2)nanostructures is beneficial for capturing and reacting with polysulfides to alleviate their shuttle effect in Li-S batteries.展开更多
Miniaturization of efficient thermoelectric(TE)devices has long been hindered by the weak mechanical strength and insufficient heat-to-electricity conversion efficiency of zone-melted(ZM)ingots.Here,we successfully pr...Miniaturization of efficient thermoelectric(TE)devices has long been hindered by the weak mechanical strength and insufficient heat-to-electricity conversion efficiency of zone-melted(ZM)ingots.Here,we successfully prepared a robust high-performance p-type Bi_(0.4)Sb_(1.6)Te_(3.72)bulk alloy by combining an ultrafast thermal explosion reaction with the spark plasma sintering(TER-SPS)process.It is observed that the introduced excess Te not only enhances the(00l)-oriented texture to ensure an outstanding power factor(PF)of 5 mW m^(−1)K^(−2),but also induces extremely high-density line defects of up to 10^(11)–10^(12)cm^(−2).Benefiting from such heavily dense line defects,the enhancement of the electronic thermal conductance from the increased electron mobility is fully compensated by the stronger phonon scattering,leading to an evident net reduction in total thermal conductivity.As a result,a superior ZT value of~1.4 at 350 K is achieved,which is 40%higher than that of commercial ZM ingots.Moreover,owing to the strengthening of grain refinement and highdensity line defects,the mechanical compressive stress reaches up to 94 MPa,which is 154%more than that of commercial single crystals.This research presents an effective strategy for the collaborative optimization of the texture,TE performance,and mechanical strength of Bi2Te3-based materials.As such,the present study contributes significantly to the future commercial development of miniature TE devices.展开更多
Sodium ion batteries(SIBs)and potassium ion batteries(PIBs)have caught numerous attention due to the low cost and abundant availability of sodium and potassium.However,their power density,cycling stability and safety ...Sodium ion batteries(SIBs)and potassium ion batteries(PIBs)have caught numerous attention due to the low cost and abundant availability of sodium and potassium.However,their power density,cycling stability and safety need further improvement for practical applications.Investigations on the reaction mechanisms and structural degradation when cycling are of great importance.In situ transmission electron microscopy(TEM)is one of the most significant techniques to understand and monitor electrochemical processes at an atomic scale with real-time imaging.In this review,the current progress in unraveling reaction mechanisms of electrode materials for SIBs and PIBs via in situ TEM is summarized.First,the importance of in situ TEM is highlighted.Then,based on the three types of electrochemical reaction,i.e.,intercalation reac-tion,conversion reaction and alloying reaction,the structural evolution and reaction kinetics at atomic resolution,and their relation to the electrochemical performance of electrode materials are reviewed and described in detail.Fi-nally,future directions of in situ TEM for SIBs and PIBs are proposed.Therefore,the in‐depth understanding revealed by in situ TEM will give an instructive guide in rational design of electrode materials for high performance electrode materials of SIBs and PIBs.展开更多
Synergistically regulating carrier and phonon transport on the nanoscale is extremely difficult for all thermoelectric(TE)materials without cage structures.Herein BaFe_(12)O_(19)/Bi_(2)Te_(2.5)Se_(0.5)thermoelectromag...Synergistically regulating carrier and phonon transport on the nanoscale is extremely difficult for all thermoelectric(TE)materials without cage structures.Herein BaFe_(12)O_(19)/Bi_(2)Te_(2.5)Se_(0.5)thermoelectromagnetic nanocomposites are designed and synthesized as a benchmarking example to simultaneously tailor the transport properties on the nanoscale.A magneto-trapped carrier effect induced by BaFe_(12)O_(19)hard-magnetic nanoparticles(NPs)is discovered,which can lower the carrier concentration of n-type Bi_(2)Te_(2.5)Se_(0.5)matrix by 16%,and increase the Seebeck coefficient by 16%.Meanwhile,BaFe_(12)O_(19)NPs provide phonon scattering centers and reduce the thermal conductivity by 12%.As a result,the ZT value of the nanocomposites is enhanced by more than 25%in the range of 300-450 K,and the cooling temperature difference increases by 65%near room temperature.This work greatly broadens the commercial application potential of ntype Bi_(2)Te_(2.5)Se_(0.5),and demonstrates magneto-trapped carrier effect as a universal strategy to enhance the electro-thermal conversion performance of TE materials with high carrier concentration.展开更多
Strain engineering is a promising method for tuning the electronic properties of two-dimensional(2 D)materials,which are capable of sustaining enormous strain thanks to their atomic thinness.However,applying a large a...Strain engineering is a promising method for tuning the electronic properties of two-dimensional(2 D)materials,which are capable of sustaining enormous strain thanks to their atomic thinness.However,applying a large and homogeneous strain on these 2D materials,including the typical semiconductor MoS_(2),remains cumbersome.Here we report a facile strategy for the fabrication of highly strained MoS_(2) via chalcogenide substitution reaction(CSR)of MoTe_(2) with lattice inheritance.The MoS_(2)resulting from the sulfurized MoTe_(2) sustains ultra large in-plane strain(approaching its strength limit~10%)with great homogeneity.Furthermore,the strain can be deterministically and continuously tuned to~1.5%by simply varying the processing temperature.Thanks to the fine control of our CSR process,we demonstrate a heterostructure of strained MoS_(2)/MoTe_(2)with abrupt interface.Finally,we verify that such a large strain potentially allows the modulation of MoS_(2) bandgap over an ultra-broad range(~1 e V).Our controllable CSR strategy paves the way for the fabrication of highly strained 2D materials for applications in devices.展开更多
Although traditional ferroelectric materials are usually dielectric and nonconductive,GeTe is a typical ferroelectric semiconductor,possessing both ferroelectric and semiconducting properties.GeTe is also a widely stu...Although traditional ferroelectric materials are usually dielectric and nonconductive,GeTe is a typical ferroelectric semiconductor,possessing both ferroelectric and semiconducting properties.GeTe is also a widely studied thermoelectric material,whose performance has been optimized by doping with various elements.However,the impact of the ferroelectric domains on the thermoelectric properties remains unclear due to the difficulty to directly observe the ferroelectric domains and their evolutions under actual working conditions where the material is exposed to high temperatures and electric currents.Herein,based on in-situ investigations of the ferroelectric domains and domain walls in both pure and Sb-doped GeTe crystals,we have been able to analyze the dynamic evolution of the ferroelectric domains and domain walls,exposed to an electric field and temperature.Local structural heterogeneities and nano-sized ferroelectric domains are generated due to the interplay of the Sb^(3+)dopant and the Ge-vacancies,leading to the increased number of charged domain walls and a much improved thermoelectric performance.This work reveals the fundamental mechanism of ferroelectric thermoelectrics and provides insights into the decoupling of previously interdependent properties such as thermo-power and electrical conductivity.展开更多
As the core components of fifth-generation(5G)communication technology,optical modules should be consistently miniaturized in size while improving their level of integration.This inevitably leads to a dramatic spike i...As the core components of fifth-generation(5G)communication technology,optical modules should be consistently miniaturized in size while improving their level of integration.This inevitably leads to a dramatic spike in power consumption and a consequent increase in heat flow density when operating in a confined space.To ensure a successful start-up and operation of 5G optical modules,active cooling and precise temperature control via the Peltier effect in confined space is essential yet challenging.In this work,p-type Bi_(0.5)Sb_(1.5)Te_(3)and n-type Bi_(2)Te_(2.7)Se_(0.3)bulk thermoelectric(TE)materials are used,and a micro thermoelectric thermostat(micro-TET)(device size,2×9.3×1.1mm^(3);leg size,0.4×0.4×0.5mm^(3);number of legs,44)is successfully integrated into a 5G optical module with Quad Small Form Pluggable 28 interface.As a result,the internal temperature of this kind of optical module is always maintained at 45.7℃ and the optical power is up to 7.4 dBm.Furthermore,a multifactor design roadmap is created based on a 3D numerical model using the ANSYS finite element method,taking into account the number of legs(N),leg width(W),leg length(L),filling atmosphere,electric contact resistance(Rec),thermal contact resistance(Rtc),ambient temperature(Ta),and the heat generated by the laser source(QL).It facilitates the integrated fabrication of micro-TET,and shows the way to enhance packaging and performance under different operating conditions.According to the roadmap,the micro-TET(2×9.3×1mm^(3),W=0.3 mm,L=0.4 mm,N=68 legs)is fabricated and consumes only 0.89W in cooling mode(Q_(L)=0.7W,T_(a)=80℃)and 0.36Win heating mode(T_(a)=0℃)to maintain the laser temperature of 50℃.This research will hopefully be applied to other microprocessors for precise temperature control and integrated manufacturing.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:11902185,11972219,U21A2086National Key Research and Development Program of China,Grant/Award Number:2020YFB0704503+1 种基金Young Elite Scientist Sponsorship Program by CAST,Grant/Award Number:2019QNRC001Shanghai Sailing Program,Grant/Award Number:19YF1415100。
文摘Although advanced anode materials for the lithium-ion battery have been investigated for decades,a reliable,high-capacity,and durable material that can enable a fast charge remains elusive.Herein,we report that a metal phosphorous trichalcogenide of MnPS_(3)(manganese phosphorus trisulfide),endowed with a unique and layered van der Waals structure,is highly beneficial for the fast insertion/extraction of alkali metal ions and can facilitate changes in the buffer volume during cycles with robust structural stability.The few-layered MnPS_(3)anodes displayed the desirable specific capacity and excellent rate chargeability owing to their good electronic and ionic conductivities.When assembled as a half-cell lithium-ion battery,a high reversible capacity of 380 mA h g^(−1)was maintained by the MnPS_(3)after 3000 cycles at a high current density of 4 A g^(−1),with a capacity retention of close to or above 100%.In full-cell testing,a reversible capacity of 450 mA h g^(−1)after 200 cycles was maintained as well.The results of in-situ TEM revealed that MnPS_(3)nanoflakes maintained a high structural integrity without exhibiting any pulverization after undergoing large volumetric expansion for the insertion of a large number of lithium ions.Their kinetics of lithium-ion diffusion,stable structure,and high pseudocapacitance contributed to their comprehensive performance,for example,a high specific capacity,rapid charge-discharge,and long cyclability.MnPS_(3)is thus an efficient anode for the next generation of batteries with a fast charge/discharge capability.
基金the support by the National Natural Science Foundation of China(11972219 and 11902185)the support of Shanghai Sailing Program(19YF1415100)+2 种基金the Young Elite Scientist Sponsorship Program by CAST(2019QNRC001)the support of the National Natural Science Foundation of China(52090022)the Natural Science Foundation for Distinguished Young Scholars of Hebei Province(E2020203085)。
文摘The electrochemical performance of lithium-ion batteries,i.e.specific capacity and cyclability,is primarily determined by chemical reversibility and structural stability of the electrodes in cycling.Here we have investigated the fundamental reaction behaviors of nickel sulfide(NixSy)as lithium-ion battery anodes by in-situ TEM.We find that Ni_(3)S_(2)is the electrochemically stable phase,which appears in the first cycle of the NixSyanode.From the second cycle,conversion between Ni_(3)S_(2)and Li_(2)S/Ni is the dominant electrochemical reaction.In lithiation,the NixSynanoparticles evolve into a mixture of Ni nanocrystals embedded in Li_(2)S matrix,which form a porous structure upon full lithiation,and with the recrystallization of the Ni_(3)S_(2)phase in delithiation,a compact and interconnected network is built.Structural stability in cycles is susceptible to particle size and substrate restraint.Carbon substrate can certainly improve the tolerance for size-dependent pulverization of NixSynanoparticles.When NixSynanoparticle exceeds the critical size value,the morphology of the particle is no longer well maintained even under the constraints of the carbon substrate.This work deepens the understanding of electrochemical reaction behavior of conversiontype materials and helps to rational design of high-energy density battery anodes.
文摘An oil-based drilling fluid should be stable and tolerant to high temperatures for use in deep drilling. An invert emulsion of water in oil is a good choice as an oil- based drilling fluid which is a mixture of a solid phase and two immiscible liquid phases stabilized by a polymeric surfactant. In deep drilling, due to high temperatures, the polymeric surfactant degrades and a phase separation occurs. Here, octadecyltrimethoxysilane-modified silica nanoparticles were used to form a stable invert emulsion of water in oil for the drilling fluid model which resulted in a milky fluid with the formation of 60 gm water droplets. In addition, rheological study showed that using hydrophobic silica nanoparticles resulted in a stable water in oil invert emulsion with desired properties for a drilling fluid that can be modified by adjusting the nanoparticle nature and content. Aging experiments at 120 ℃ indicated that they also have good stability at high temperatures for challenging drilling operations.
基金the financial support of the Fundamental Research Funds for the Central Universities(No.40120631)the National Natural Science Foundation of China(No.52202291)for the support.+1 种基金C.C.acknowledges the financial support of Natural Science Foundation of Hubei Province(No.2022CFB388)the Natural Science Foundation of Hainan Province of China(No.623MS068).
文摘Transition metal-based layered double hydroxides(LDHs)have been capable of working efficiently as catalysts in the basic oxygen evolution reaction(OER)for sustaining hydrogen production of alkaline water electrolysis.Nevertheless,exploring new LDH-based electrocatalysts featuring both remarkable activity and good stability is still in high demand,which is pivotal for comprehensive understanding and impressive improvement of the sluggish OER kinetics.Here,a series of bimetallic(Co and Mo)LDH arrays were designed and fabricated via a facile and controlled strategy by incorporating a Mo source into presynthesized Co-based metal-organic framework(MOF)arrays on carbon cloth(CC),named as ZIF-67/CC arrays.We found that tuning the Mo content resulted in gradual differences in the structural properties,surface morphology,and chemical states of the resulting catalysts,namely CoMox-LDH/CC(x representing the added weight of the Mo source).Gratifyingly,the best-performing CoMo_(0.20)-LDH/CC electrocatalyst demonstrates a low overpotential of only 226 mV and high stability at a current density of 10 mA·cm^(−2),which is superior to most LDH-based OER catalysts reported previously.Furthermore,it only required 1.611 V voltage to drive the overall water splitting device at the current density of 10 mA·cm^(−2).The present study represents a significant advancement in the development and applications of new OER catalysts.
基金National Key Research and Development Program of China,Grant/Award Number:2023YFB4502200National Natural Science Foundation of China,Grant/Award Numbers:52372149,U21A2069+2 种基金Innovation Project of Optics Valley Laboratory,Grant/Award Number:OVL2023PY007Guangdong HUST Industrial Technology Research Institute,Guangdong Provincial Key Laboratory of Manufacturing Equipment Digitization,Grant/Award Number:2023B1212060012Interdiciplinary Research Program of HUST,Grant/Award Number:2024JCYJ008。
文摘Local phase transition in transition metal dichalcogenides (TMDCs) by lithiumintercalation enables the fabrication of high-quality contact interfaces in twodimensional(2D) electronic devices. However, controlling the intercalation oflithium is hitherto challenging in vertically stacked van der Waalsheterostructures (vdWHs) due to the random diffusion of lithium ions in thehetero-interface, which hinders their application for contact engineering of 2DvdWHs devices. Herein, a strategy to restrict the lithium intercalation pathwayin vdWHs is developed by using surface-permeation assisted intercalationwhile sealing all edges, based on which a high-performance edge-contact MoS_(2)vdWHs floating-gate transistor is demonstrated. Our method avoids intercalationfrom edges that are prone to be random but intentionally promotes lithiumintercalation from the top surface. The derived MoS_(2) floating-gatetransistor exhibits improved interface quality and significantly reduced subthresholdswing (SS) from >600 to 100 mV dec^(–1). In addition, ultrafast program/erase performance together with well-distinguished 32 memory statesare demonstrated, making it a promising candidate for low-power artificialsynapses. The study on controlling the lithium intercalation pathways in 2DvdWHs offers a viable route toward high-performance 2D electronics for memoryand neuromorphic computing purposes.
文摘Segmented block copolymer based on nylon6 （N6） and polyethylene oxide （PEO） with stochiometric ratio was synthesized via a two-step process. The first step represents end capping of N6 in the presence of adipic acid leading to carboxy terminated N6, and the second one is polycondensation of the latter product with PEO in the presence of catalyst and thermostabilizer to form a high molecular weight multi-block copolymer. Several methods were applied to characterize the synthesized copolyrner such as Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, differential thermal analysis, differential scanning calorimetry, X-ray diffraction and atomic force microscopy. The obtained results confirmed the multi-block structure for copolymer with a very high degree of micro-phase separation. Atomic force microscopy micrographs indicated that the morphology was the dispersion of high stiffness nanostructured polyamide （PA） domains in the amorphous region of PEO matrix, which can be very important in their performance for membrane processes.
基金supported by the Key Research and Development Program of Hubei Province(2021BAA176)Hainan Provincial Natural Science Foundation of China(522CXTD516)。
文摘单质硅是一种有潜力的高容量锂离子电池负极材料.然而,受限于充放电过程中巨大的体积膨胀,其循环性能并不理想.在这个工作中,我们设计了一种独特的三组分复合负极材料(Si/Cr_(2)O_(3)/C),其中Si纳米颗粒被限域在碳包覆的氧化铬多层空心球(MSHSs)中.得益于Cr_(2)O_(3)/C基体的体积变化缓冲能力与优异的结构稳定性,将Si纳米颗粒封装在MSHSs中可以有效地提高其电化学性能.合理的结构设计赋予了Si/Cr_(2)O_(3)/C三组分复合材料高的可逆容量(在100 mA g^(-1)的电流密度下,比容量为1351 mA h g^(-1))和稳定的循环性能(在500 mA g^(-1)的电流密度下,循环300次后比容量保持在716 mA h g^(-1)).这一工作提出了一种多壳层空心结构设计的新思路,以解决硅基负极材料循环性差的瓶颈.
基金financially supported by the National Natural Science Foundation of China(Nos.52127816,520722825 and 2022072)the Hubei Provincial Natural Science Foundation of China(Distinguished Young Scholars,No.2022CFA042)the In-dependent Innovation Projects of the Hubei Longzhong Laboratory(No.2022ZZ-10).
文摘Transition metal oxides with layered structure have been widely used as cathode materials for lithium-ion batteries(LIBs)which have relatively high energy density,large capacity and long life.However,in the long-term electrochemical cycle,the inevitable degradation of performance of LIBs due to structural degradation in cathodes severely restricts their large-scale practical applications.Understanding the underlying mechanism of structural degradation is the most critical scientific problem.Recently,in situ transmission electron microscopy(TEM)has become a useful tool to study the structural and compositional evolutions at atomic scale in electrochemical reactions,which provided a unique and in-depth understanding of the structural degradation.In this review,we discuss the recent advances in the in situ TEM,focusing on its role in revealing the structural degradation mechanisms in the four key places:(1)the interface between the cathodes and electrolyte;(2)the cathode surface;(3)the particle interior and(4)those induced by thermal effect.The insight gained by the in-situ TEM which is still developing at its fast pace is unique and expected to provide guidance for designing better layered cathode materials.
基金supported by the National Key Research and Development Program of China(2021YFB3800300 and 2018YFE0206900)the National Natural Science Foundation of China(21825103,U21A2069,and 52072138)。
基金supported by the Ministry of Science and Technology of China(2021YFA1200501)the National Natural Science Foundation of China(U22A20137,U21A2069,and 21825103)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2020A1515110330)Shenzhen Science and Technology Innovation Program(JCYJ20220818102215033,GJHZ20210705142542015,and JCYJ20220530160811027)the support from the Queen Mary–HUST Strategic Partner Fund。
基金the National Natural Science Foundation of China(Nos.21972016 and 21773023)National Youth Top-notch Talent Support Program of China,Sichuan Science and Technology Program(No.2020YJ0243)+1 种基金Jiangsu Province Cultivation base for State Key Laboratory of Photovoltaic Science and Technology(No.SKLPST 202103)Foundation of State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(No.2022-K28).
文摘Developing efficient platinum-based electrocatalysts with super durability for the oxygen reduction reaction(ORR)is highly desirable to promote the large-scale commercialization of fuel cells.Although progress has been made in this aspect,the electrochemical kinetics and stability of platinum-based catalysts are still far from the requirements of the practical applications.Herein,PtPdFeCoNi high-entropy alloy(HEA)nanoparticles were demonstrated via a high-temperature injection method.PtPdFeCoNi HEA nanocatalyst exhibits outstanding catalytic activity and stability towards ORR due to the high entropy,lattice distortion,and sluggish diffusion effects of HEA,and the HEA nanoparticles delivered a mass activity of 1.23 A/mgPt and a specific activity of 1.80 mA/cmPt 2,which enhanced by 6.2 and 4.9 times,respectively,compared with the values of the commercial Pt/C catalyst.More importantly,the high durability of PtPdFeCoNi HEA/C was evidenced by only 6 mV negativeshifted half-wave potential after 50,000 cycles of accelerated durability test(ADT).
基金the National Key R&D Program of China(2016YFA0202602)the National Natural Science Foundation of China(U1663225)+3 种基金the Fundamental Research Funds for the Central Universities(2020-YB-009)the Academy of Scientific Research and Technology(6611,ASRT,Egypt)the 111 National project(B20002)from the Ministry of Science and Technology and the Ministry of Education,ChinaSinopec Ministry of Science and Technology Basic Prospective Research Project(217027-5 and 218025-9)。
文摘Lithium-sulfur(Li-S)batteries have attracted significant attention for their high specific capacity,non-toxic and harmless advantages.However,the shuttle effect limits their development.In this work,small-sized tin disulfide(SnS_(2))nanoparticles are embedded between interlayers of twodimensional porous carbon nanosheets(PCNs),forming a multi-functional nanocomposite(PCN-SnS_(2))as a cathode carrier for Li-S batteries.The graphitized carbon nanosheets improve the overall conductivity of the electrode,and the abundant pores not only facilitate ion transfer and electrolyte permeation,but also buffer the volume change during the charge and discharge process to ensure the integrity of the electrode material.More importantly,the physical confinement of PCN,as well as the strong chemical adsorption and catalytic reaction of small SnS_(2)nanoparticles,synergistically reduce the shuttle effect of polysulfides.The interaction between a porous layered structure and physical-chemical confinement gives the PCN-SnS_(2)-S electrode high electrochemical performance.Even at a high rate of 2 C,a discharge capacity of 650 mA h g^(-1)is maintained after 150 cycles,underscoring the positive results of SnS_(2)-based materials for Li-S batteries.The galvanostatic intermittent titration technique results further confirm that the PCN-SnS_(2)-S electrode has a high Li+transmission rate,which reduces the activation barrier and improves the electrochemical reaction kinetics.This work provides strong evidence that reducing the size of SnS_(2)nanostructures is beneficial for capturing and reacting with polysulfides to alleviate their shuttle effect in Li-S batteries.
基金financially supported by the National Key Research and Development Program of China (2018YFB0703600)the National Natural Science Foundation of China (51772232)+1 种基金the 111 Project of China (B07040)Wuhan Frontier Project on Applied Research Foundation (2019010701011405)
文摘Miniaturization of efficient thermoelectric(TE)devices has long been hindered by the weak mechanical strength and insufficient heat-to-electricity conversion efficiency of zone-melted(ZM)ingots.Here,we successfully prepared a robust high-performance p-type Bi_(0.4)Sb_(1.6)Te_(3.72)bulk alloy by combining an ultrafast thermal explosion reaction with the spark plasma sintering(TER-SPS)process.It is observed that the introduced excess Te not only enhances the(00l)-oriented texture to ensure an outstanding power factor(PF)of 5 mW m^(−1)K^(−2),but also induces extremely high-density line defects of up to 10^(11)–10^(12)cm^(−2).Benefiting from such heavily dense line defects,the enhancement of the electronic thermal conductance from the increased electron mobility is fully compensated by the stronger phonon scattering,leading to an evident net reduction in total thermal conductivity.As a result,a superior ZT value of~1.4 at 350 K is achieved,which is 40%higher than that of commercial ZM ingots.Moreover,owing to the strengthening of grain refinement and highdensity line defects,the mechanical compressive stress reaches up to 94 MPa,which is 154%more than that of commercial single crystals.This research presents an effective strategy for the collaborative optimization of the texture,TE performance,and mechanical strength of Bi2Te3-based materials.As such,the present study contributes significantly to the future commercial development of miniature TE devices.
基金This work was supported by the National Natural Science Foundation of China(52072282)The authors also wish to acknowledge support from the National Key Research and Development Program of China(2019YFA0704900)the Fundamental Research Fund for the Central Universities(WUT:2021III016GX).
文摘Sodium ion batteries(SIBs)and potassium ion batteries(PIBs)have caught numerous attention due to the low cost and abundant availability of sodium and potassium.However,their power density,cycling stability and safety need further improvement for practical applications.Investigations on the reaction mechanisms and structural degradation when cycling are of great importance.In situ transmission electron microscopy(TEM)is one of the most significant techniques to understand and monitor electrochemical processes at an atomic scale with real-time imaging.In this review,the current progress in unraveling reaction mechanisms of electrode materials for SIBs and PIBs via in situ TEM is summarized.First,the importance of in situ TEM is highlighted.Then,based on the three types of electrochemical reaction,i.e.,intercalation reac-tion,conversion reaction and alloying reaction,the structural evolution and reaction kinetics at atomic resolution,and their relation to the electrochemical performance of electrode materials are reviewed and described in detail.Fi-nally,future directions of in situ TEM for SIBs and PIBs are proposed.Therefore,the in‐depth understanding revealed by in situ TEM will give an instructive guide in rational design of electrode materials for high performance electrode materials of SIBs and PIBs.
基金the National Natural Science Foundation of China(11834012,51620105014,91963207,91963122 and 51902237)the National Key Research and Development Program of China(2018YFB0703603,2019YFA0704900 and SQ2018YFE010905)Foshan Xianhu Laboratory of Advanced Energy Science and Technology Guangdong Laboratory(XHT2020-004)。
文摘Synergistically regulating carrier and phonon transport on the nanoscale is extremely difficult for all thermoelectric(TE)materials without cage structures.Herein BaFe_(12)O_(19)/Bi_(2)Te_(2.5)Se_(0.5)thermoelectromagnetic nanocomposites are designed and synthesized as a benchmarking example to simultaneously tailor the transport properties on the nanoscale.A magneto-trapped carrier effect induced by BaFe_(12)O_(19)hard-magnetic nanoparticles(NPs)is discovered,which can lower the carrier concentration of n-type Bi_(2)Te_(2.5)Se_(0.5)matrix by 16%,and increase the Seebeck coefficient by 16%.Meanwhile,BaFe_(12)O_(19)NPs provide phonon scattering centers and reduce the thermal conductivity by 12%.As a result,the ZT value of the nanocomposites is enhanced by more than 25%in the range of 300-450 K,and the cooling temperature difference increases by 65%near room temperature.This work greatly broadens the commercial application potential of ntype Bi_(2)Te_(2.5)Se_(0.5),and demonstrates magneto-trapped carrier effect as a universal strategy to enhance the electro-thermal conversion performance of TE materials with high carrier concentration.
基金supported by the National Natural Science Foundation of China(21825103,52001165)Natural Science Foundation of Hubei Province(2019CFA002)+2 种基金Natural Science Foundation of Jiangsu Province(BK20200475)the Fundamental Research Funds for the Central Universities(2019kfy XMBZ018,30921011215)supports from Analytical and Testing Center in Huazhong University of Science and Technology as well as Nanostructure Research Center(NRC)supported by the Fundamental Research Funds for the Central Universities(WUT:2019III012GX,2020III002GX)。
文摘Strain engineering is a promising method for tuning the electronic properties of two-dimensional(2 D)materials,which are capable of sustaining enormous strain thanks to their atomic thinness.However,applying a large and homogeneous strain on these 2D materials,including the typical semiconductor MoS_(2),remains cumbersome.Here we report a facile strategy for the fabrication of highly strained MoS_(2) via chalcogenide substitution reaction(CSR)of MoTe_(2) with lattice inheritance.The MoS_(2)resulting from the sulfurized MoTe_(2) sustains ultra large in-plane strain(approaching its strength limit~10%)with great homogeneity.Furthermore,the strain can be deterministically and continuously tuned to~1.5%by simply varying the processing temperature.Thanks to the fine control of our CSR process,we demonstrate a heterostructure of strained MoS_(2)/MoTe_(2)with abrupt interface.Finally,we verify that such a large strain potentially allows the modulation of MoS_(2) bandgap over an ultra-broad range(~1 e V).Our controllable CSR strategy paves the way for the fabrication of highly strained 2D materials for applications in devices.
基金supported by the National Natural Science Foundation of China(52072282)the National Key Research and Development Program of China(2019YFA0704900)performed at the Nanostructure Research Center(NRC),which is supported by the Fundamental Research Funds for the Central Universities(WUT:2021Ⅲ016GX)。
文摘Although traditional ferroelectric materials are usually dielectric and nonconductive,GeTe is a typical ferroelectric semiconductor,possessing both ferroelectric and semiconducting properties.GeTe is also a widely studied thermoelectric material,whose performance has been optimized by doping with various elements.However,the impact of the ferroelectric domains on the thermoelectric properties remains unclear due to the difficulty to directly observe the ferroelectric domains and their evolutions under actual working conditions where the material is exposed to high temperatures and electric currents.Herein,based on in-situ investigations of the ferroelectric domains and domain walls in both pure and Sb-doped GeTe crystals,we have been able to analyze the dynamic evolution of the ferroelectric domains and domain walls,exposed to an electric field and temperature.Local structural heterogeneities and nano-sized ferroelectric domains are generated due to the interplay of the Sb^(3+)dopant and the Ge-vacancies,leading to the increased number of charged domain walls and a much improved thermoelectric performance.This work reveals the fundamental mechanism of ferroelectric thermoelectrics and provides insights into the decoupling of previously interdependent properties such as thermo-power and electrical conductivity.
基金National Key Research and Development Program of China,Grant/Award Number:2019YFA0704900National Natural Science Foundation of China,Grant/Award Number:52202289。
文摘As the core components of fifth-generation(5G)communication technology,optical modules should be consistently miniaturized in size while improving their level of integration.This inevitably leads to a dramatic spike in power consumption and a consequent increase in heat flow density when operating in a confined space.To ensure a successful start-up and operation of 5G optical modules,active cooling and precise temperature control via the Peltier effect in confined space is essential yet challenging.In this work,p-type Bi_(0.5)Sb_(1.5)Te_(3)and n-type Bi_(2)Te_(2.7)Se_(0.3)bulk thermoelectric(TE)materials are used,and a micro thermoelectric thermostat(micro-TET)(device size,2×9.3×1.1mm^(3);leg size,0.4×0.4×0.5mm^(3);number of legs,44)is successfully integrated into a 5G optical module with Quad Small Form Pluggable 28 interface.As a result,the internal temperature of this kind of optical module is always maintained at 45.7℃ and the optical power is up to 7.4 dBm.Furthermore,a multifactor design roadmap is created based on a 3D numerical model using the ANSYS finite element method,taking into account the number of legs(N),leg width(W),leg length(L),filling atmosphere,electric contact resistance(Rec),thermal contact resistance(Rtc),ambient temperature(Ta),and the heat generated by the laser source(QL).It facilitates the integrated fabrication of micro-TET,and shows the way to enhance packaging and performance under different operating conditions.According to the roadmap,the micro-TET(2×9.3×1mm^(3),W=0.3 mm,L=0.4 mm,N=68 legs)is fabricated and consumes only 0.89W in cooling mode(Q_(L)=0.7W,T_(a)=80℃)and 0.36Win heating mode(T_(a)=0℃)to maintain the laser temperature of 50℃.This research will hopefully be applied to other microprocessors for precise temperature control and integrated manufacturing.
