We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density...We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density functional theory.The results show that there are band crossings in the Z-L(armchair)direction.展开更多
Piezoelectric materials have advantages of fine-tuning photocatalytic performance through harvesting mechanical energy and open a new avenue in facilitating green catalytic reaction.Herein,polyvinylidene fluoride(PVDF...Piezoelectric materials have advantages of fine-tuning photocatalytic performance through harvesting mechanical energy and open a new avenue in facilitating green catalytic reaction.Herein,polyvinylidene fluoride(PVDF),a flexible piezoelectric material,was introduced to synthesize a novel Cd_(0.9)Zn_(0.1)S-ZnO@C/PVDF(CZS-ZO@C/PVDF)piezo-photocatalytic film by spin coating and immersion phase conversion method.Benefiting from the piezoelectricity of PVDF and the internal electric field(IEF)of CZS-ZO@C Step-scheme(S-Scheme)heterojunction,CZS-ZO@C/PVDF was able to induce a hydrogen generation rate of 34.9 mmol g^(−1)h^(−1)activated by ultrasound and visible light(U-L),which is∼17.5 times of Cd_(0.9)Zn_(0.1)S/PVDF(CZS/PVDF)and∼7.4 times of the photocatalysis rate activated by visible light only(L).Piezoelectric measurements and COMSOL simulation illustrated the excellent piezoelectricity of CZS-ZO@C/PVDF film,which exhibits a piezoelectric coefficient(d33)of 9.9 pm V−1 and a piezoelectric potential of 874 mV(under 0.5 MPa).The reaction mechanism for the exceptional piezo-photocatalytic performance was finally disclosed through density functional theory(DFT)calculation and electrochemical tests.This study enriches the application scope of piezoelectric materials in sustainable energy catalysis and provides a new direction to develop efficient piezoelectric photocatalysts.展开更多
Cation vacancies can bring numerous surprising characters due to its multifarious electron and orbit distribution.In this work,d-MnO_(2) with alkali-ion(K,Na,Li)associated manganese(Mn)vacancies is fabricated by a sim...Cation vacancies can bring numerous surprising characters due to its multifarious electron and orbit distribution.In this work,d-MnO_(2) with alkali-ion(K,Na,Li)associated manganese(Mn)vacancies is fabricated by a simple hydrothermal reaction,and the correlation between their electronic structure and pseudocapacitance are systematically investigated.FESEM/TEM images have shown that the morphology of MnO_(2) is obviously changed after the introducing of cation vacancies.The position of alkali-ion in MnO_(2) structure can be controlled by adjusting the ion concentration.XRD patterns and Raman spectra demonstrate that the alkali-ion is embedded in Mn vacancies at low concentration,while entered the interlayer of MnO_(2) at high concentration.The existence of Mn vacancies will resulting in the distortion of neighboring atoms,leading to the electronic delocalization,and thus enhancing the conductivity,pseudocapacitance and rate capability of MnO_(2).Accordingly,the specific capacitances of optimized 0.4 KMO,0.4 NaMO and 0.4 LiMO samples are enhanced about 1.9,1.6 and 1.6 times compared to pure MnO_(2).Meanwhile,the rate performance has also been improved about 76%,46%and 42%,respectively.Theoretical calculations further confirm that the Mn vacancies can generate additional occupancy states and cause an increase in carrier concentration,which will improve the conductivity and further boost the pseudocapacitance of MnO_(2).This result open up a promising approach to explore active and durable electrode materials.展开更多
Rational design of photocatalyst to maximize the use of sunlight is one of the issues to be solved in photocatalysis technology.In this study,the CuFe_(2)O_(4)@C/Cd_(0.9)Zn_(0.1)S(CFO@C/CZS)S-scheme photocatalyst with...Rational design of photocatalyst to maximize the use of sunlight is one of the issues to be solved in photocatalysis technology.In this study,the CuFe_(2)O_(4)@C/Cd_(0.9)Zn_(0.1)S(CFO@C/CZS)S-scheme photocatalyst with photothermal effect was synthesized by ultrasonic self-assembly combined with calcination.The dark CFO@C absorbed visible light and partly converted into heat to promote the hydrogen evolution reaction.The presence of heterojunctions inhibited the photogenerated electron-hole recombination.The graphite-carbon layer provided a stable channel for electron transfer,and the presence of magnetic CFO made recycle easier.Under the action of photothermal assistance and heterojunction,the hydrogen evolution rate of the optimal CFO@C/CZS was 80.79 mmol g^(-1) h^(-1),which was 2.55 times and 260.61 times of that of pure CZS and CFO@C,respectively.Notably,the composite samples also exhibit excellent stability and a wide range of environmental adaptability.Through experimental tests and first-principles simulation calculation methods,the plausible mechanism of photoactivity enhancement was proposed.This work provided a feasible strategy of photothermal assistance for the development of heterojunction photocatalysts with distinctive hydrogen evolution.展开更多
The combustion characteristics of styrene-butadiene-styrene （SBS） asphalt are studied by thermogravimetric analysis （TG/DTG） at four different heating rates. According to the saturates/aromatics/resins/asphaltenes...The combustion characteristics of styrene-butadiene-styrene （SBS） asphalt are studied by thermogravimetric analysis （TG/DTG） at four different heating rates. According to the saturates/aromatics/resins/asphaltenes （SARA） fractionation method, the combustion process of SBS asphalt can be divided by Gaussian peak fitting into three main stages： oil content release, resin pyrolysis, and asphaltene and char combustion. When the heating rate increases, the mass losses of the oil content and resin pyrolysis increase, and less asphaltenes are formed at a higher temperature. The activation energy values are calculated by the Coats-Redfern method to be in the range 61.6 kJ/mol-142.9 kJ/mol. The Popescu method is used for the kinetic analysis, and the result shows that the three stages of asphalt combustion can be explained by the sphere phase boundary reaction model, the second order chemical reaction model, nucleation, and its subsequent growth model, respectively.展开更多
Energy storage is an ever-growing global concern due to increased energy needs and resource exhaustion.Sodium-ion batteries(SIBs)have called increasing attention and achieved substantial progress in recent years owing...Energy storage is an ever-growing global concern due to increased energy needs and resource exhaustion.Sodium-ion batteries(SIBs)have called increasing attention and achieved substantial progress in recent years owing to the abundance and even distribution of Na resources in the crust,and the predicted low cost of the technique.Nevertheless,SIBs still face challenges like lower energy density and inferior cycling stability compared to mature lithium-ion batteries(LIBs).Enhancing the electrochemical performance of SIBs requires an in-deep and comprehensive understanding of the improvement strategies and the underlying reaction mechanism elucidated by in situ techniques.In this review,commonly applied in situ techniques,for instance,transmission electron microscopy(TEM),Raman spectroscopy,X-ray diffraction(XRD),and X-ray absorption near-edge structure(XANES),and their applications on the representative cathode and anode materials with selected samples are summarized.We discuss the merits and demerits of each type of material,strategies to enhance their electrochemical performance,and the applications of in situ characterizations of them during the de/sodiation process to reveal the underlying reaction mechanism for performance improvement.We aim to elucidate the composition/structure-per formance relationship to provide guidelines for rational design and preparation of electrode materials toward high electrochemical performance.展开更多
A refractive index(RI)sensor based on a cladding-etched thin-core single-mode fiber(TCSMF)sandwiched between two single-mode fibers is demonstrated.The experimental results show that the sensitivity,within the RI rang...A refractive index(RI)sensor based on a cladding-etched thin-core single-mode fiber(TCSMF)sandwiched between two single-mode fibers is demonstrated.The experimental results show that the sensitivity,within the RI range of 1.333–1.340,is enhanced at least 6 times by etching.It increases with the surrounding RI and reaches 857.5 nm/RIU at RI of 1.3684,and it can be expected to be higher with the decrease of the cladding diameter of the TCSMF.展开更多
Rechargeable zinc-air batteries(ZAB)with a high theoretical energy density of 1086 Wh kg^(-1),have received tremendous research attention.However,the practical application of ZABs is still limited by high polarization...Rechargeable zinc-air batteries(ZAB)with a high theoretical energy density of 1086 Wh kg^(-1),have received tremendous research attention.However,the practical application of ZABs is still limited by high polarization and poor energy efficiency(low power density)due to the sluggish 4 electrons(e^(-))/oxygen(O_(2))kinetics over the air electrode.Here,a noble-metal-free Fe Nx C electrocatalyst is developed via a onepot approach,which provides a high density of the oxygen reduction reaction(ORR)active site and facilitates the ORR kinetics.Accordingly,the as-assembled Zn-air battery displayed a low charge–discharge voltage gap of 0.71 V at 10 m A cm^(-2),a remarkable peak power density as high as 181.2 m W cm^(-2),as well as the long-term durability for hundreds of hours,among the top level of those reported previously.Our work provides a major boost for the practical application of Zn-air battery in the future.展开更多
The influence of vacancy defect on the doping of silicon nanowires is systematically studied by the first-principles calculations. The atomic structures and electronic properties of vacancies and vacancy-boron （vacan...The influence of vacancy defect on the doping of silicon nanowires is systematically studied by the first-principles calculations. The atomic structures and electronic properties of vacancies and vacancy-boron （vacancy-phosphor） com- plexes in H-passivated silicon nanowire with a diameter of 2.3 nm are explored. The results of geometry optimization indicate that a central vacancy can exist stably, while the vacancy at the edge of the nanowire undergoes a local surface reconstruction, which results in the extradition of the vacancy out of the nanowire. Total-energy calculations indicate that the central vacancy tends to form a vacancy-dopant defect pair. Further analysis shows that n-type doping efficiency is strongly inhibited by the unintentional vacancy defect. In contrast, the vacancy defect has little effect on p-type doping. Our results suggest that the vacancy defect should be avoided during the growth and the fabrication of devices.展开更多
Asphalt materials will be ignited and release significant toxic fumes within tunnel fires. Thus, combustion character- istics of asphalt materials used in road tunnel should be studied in order to limit such an advers...Asphalt materials will be ignited and release significant toxic fumes within tunnel fires. Thus, combustion character- istics of asphalt materials used in road tunnel should be studied in order to limit such an adverse effect. In the present work we study the influence of limestone fillers on combustion characteristics of asphalt mortar by thermogravimetric and kinetic analysis. It is shown that the combustion of asphalt mortar is not just a linear superposition of asphalt and limestone. The limestone will increase the ignition point and the activation energy of the primary volatile release, and will catalyze the char formation from the primary volatile release. Kinetic analysis shows that the primary volatile release stage of asphalt mortar combustion can be explained by a three-dimensional diffusion model, the secondary volatile release and char combustion stage can be explained by a model under the assumption of random nucleation and nuclei growth, whereas the limestone decomposition stage appears to follow the one-dimensional phase boundary model.展开更多
The discovery and manipulation of topological Hall effect(THE),an abnormal magnetoelectric response mostly related to the Dzyaloshinskii–Moriya interaction(DMI),are promising for next-generation spintronic devices ba...The discovery and manipulation of topological Hall effect(THE),an abnormal magnetoelectric response mostly related to the Dzyaloshinskii–Moriya interaction(DMI),are promising for next-generation spintronic devices based on topological spin textures such as magnetic skyrmions.However,most skyrmions and THE are stabilized in a narrow temperature window either below or over room temperature with high critical current manipulation.It is still elusive and challenging to achieve large THE with both wide temperature window till room temperature and low critical current manipulation.Here,using controllable,naturally oxidized sub-20 and sub-10 nm 2D van der Waals room-temperature ferromagnetic Fe_(3)GaTe_(2-x)crystals,we report robust 2D skyrmion THE with ultrawide temperature window ranging in three orders of magnitude from 2 to 300 K,in combination with giant THE of~5.4μΩ·cm at 10 K and~0.15μΩ·cm at 300 K,which is 1–3 orders of magnitude larger than that of all known room-temperature 2D skyrmion systems.Moreover,room-temperature current-controlled THE is also realized with a low critical current density of~6.2×10^(5)A·cm^(-2).First-principles calculations unveil natural oxidation-induced highly enhanced 2D interfacial DMI reasonable for robust giant THE.This work paves the way to room-temperature electrically controlled 2D THE-based practical spintronic devices.展开更多
Quasi-bound state in the continuum(QBIC)resonance is gradually attracting attention and being applied in Goos-Hänchen(GH)shift enhancement due to its high quality(Q)factor and superior optical confinement.Current...Quasi-bound state in the continuum(QBIC)resonance is gradually attracting attention and being applied in Goos-Hänchen(GH)shift enhancement due to its high quality(Q)factor and superior optical confinement.Currently,symmetry-protected QBIC resonance is often achieved by breaking the geometric symmetry,but few cases are achieved by breaking the material symmetry.This paper proposes a dielectric compound grating to achieve a high Q factor and high-reflection symmetry-protectede QBIC resonance based on material asymmetry.Theoretical calculations show that the symmetry-protected QBIC resonance achieved by material asymmetry can significantly increase the GH shift up to-980 times the resonance wavelength,and the maximum GH shift is located at the reflection peak with unity reflectance.This paper provides a theoretical basis for designing and fabricating high-performance GH shift tunable metasurfaces/dielectric gratings in the future.展开更多
A highly sensitive all-optical atomic magnetometer based on the magnetooptical effect which uses the advanced technique of single laser beam detection is reported and demonstrated experimentally. A sensitivity of 0.5p...A highly sensitive all-optical atomic magnetometer based on the magnetooptical effect which uses the advanced technique of single laser beam detection is reported and demonstrated experimentally. A sensitivity of 0.5pT/Hz^1/2 is obtained by analyzing the magnetic noise spectrum, which exceeds that of most traditional magnetometers. This kind of atomic magnetometer is very compact, has a low power consumption, and has a high theoretical sensitivity limit, which make it suitable for many applications.展开更多
The wavelength-tunable rectangular mode-locking operation is demonstrated in an all-fiber laser based on semi- conductor saturable absorber mirror. As the dissipative soliton resonance signature, the pulse duration va...The wavelength-tunable rectangular mode-locking operation is demonstrated in an all-fiber laser based on semi- conductor saturable absorber mirror. As the dissipative soliton resonance signature, the pulse duration varies from 5SOps to 2.1 ns as a function o~ the increasing pump power. Correspondingly, the maximum pulse energy is 9.11 n3. Moreover, it is found that the wavelength tunable operation with a range of approximately 10 nm could be obtained by properly adjusting the polarization controllers. The characteristics of the rectangular pulses at different wavelengths are similar to each other. The demonstration of the wavelength tunable rectangular pulses would be beneficial to some applications for many fields such as spectroscopy and sensing research.展开更多
A fiber-optic liquid-level sensor is proposed and experimentally demonstrated.It is a Mach–Zehnder interferometer(MZI)composed of a thin-core single-mode fiber(TCSMF)without coating sandwiched between two single-mode...A fiber-optic liquid-level sensor is proposed and experimentally demonstrated.It is a Mach–Zehnder interferometer(MZI)composed of a thin-core single-mode fiber(TCSMF)without coating sandwiched between two single-mode fibers(SMFs).The transmission spectrum properties of the MZI modified by liquid around the TCSMF are used for detecting the liquid level.It is found that the sensor exhibits an excellent linear relationship between the level and the shift of interference dip wavelength and its achieved sensitivities are 0.160 nm/mm and 0.288 nm/mm for liquid with an RI of 1.3330 and 1.3696,respectively.Employing the spectrum differential integration(SDI)method to analyze transmission spectra can increase the detecting resolution of the liquid level.Due to its advantages of an extremely easy fabrication process,high sensitivity and a large sensing range,the sensor is an ideal candidate for continuous liquid level sensing.展开更多
Based on first-principles calculations, the electronic and magnetic properties of undoped and Li-doped rutile TiO2 have been studied. The results demonstrate that a cation vacancy can arouse ferromagnetism in TiO2 and...Based on first-principles calculations, the electronic and magnetic properties of undoped and Li-doped rutile TiO2 have been studied. The results demonstrate that a cation vacancy can arouse ferromagnetism in TiO2 and the magnetic moment mainly comes from p orbitals of O atoms around the Ti vacancy. However, the Ti vacancy under normal conditions is very difficult to form due to its high formation energy. Our calculations indicate that Li-doped TiO2 can reduce the formation energy while keeping the magnetism. The large magnetization energy indicates that Li-doped TiO2 is a promising room-temperature diluted magnetic semiconductor.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12104216,12241403,and 61974061)the National Key R&D Program of China(Grant No.2021YFB3601600)the Natural Science Foundation of Jiangsu Province of China(Grant No.BK20140054)。
文摘We investigate the anisotropic band structure and its evolution under tensile strains along different crystallographic directions in bulk black phosphorus(BP)using angle-resolved photoemission spectroscopy and density functional theory.The results show that there are band crossings in the Z-L(armchair)direction.
基金supported by the Shandong Provincial Natural Science Foundation,China(ZR2022ME179,ZR2021ME046).
文摘Piezoelectric materials have advantages of fine-tuning photocatalytic performance through harvesting mechanical energy and open a new avenue in facilitating green catalytic reaction.Herein,polyvinylidene fluoride(PVDF),a flexible piezoelectric material,was introduced to synthesize a novel Cd_(0.9)Zn_(0.1)S-ZnO@C/PVDF(CZS-ZO@C/PVDF)piezo-photocatalytic film by spin coating and immersion phase conversion method.Benefiting from the piezoelectricity of PVDF and the internal electric field(IEF)of CZS-ZO@C Step-scheme(S-Scheme)heterojunction,CZS-ZO@C/PVDF was able to induce a hydrogen generation rate of 34.9 mmol g^(−1)h^(−1)activated by ultrasound and visible light(U-L),which is∼17.5 times of Cd_(0.9)Zn_(0.1)S/PVDF(CZS/PVDF)and∼7.4 times of the photocatalysis rate activated by visible light only(L).Piezoelectric measurements and COMSOL simulation illustrated the excellent piezoelectricity of CZS-ZO@C/PVDF film,which exhibits a piezoelectric coefficient(d33)of 9.9 pm V−1 and a piezoelectric potential of 874 mV(under 0.5 MPa).The reaction mechanism for the exceptional piezo-photocatalytic performance was finally disclosed through density functional theory(DFT)calculation and electrochemical tests.This study enriches the application scope of piezoelectric materials in sustainable energy catalysis and provides a new direction to develop efficient piezoelectric photocatalysts.
基金supported by Zhejiang Provincial Natural Science Foundation of China under Grant No.LQ18E030005,LY18E060005,LY19E020006,LY18E020007National Natural Science Foundation of China(No.51902301)。
文摘Cation vacancies can bring numerous surprising characters due to its multifarious electron and orbit distribution.In this work,d-MnO_(2) with alkali-ion(K,Na,Li)associated manganese(Mn)vacancies is fabricated by a simple hydrothermal reaction,and the correlation between their electronic structure and pseudocapacitance are systematically investigated.FESEM/TEM images have shown that the morphology of MnO_(2) is obviously changed after the introducing of cation vacancies.The position of alkali-ion in MnO_(2) structure can be controlled by adjusting the ion concentration.XRD patterns and Raman spectra demonstrate that the alkali-ion is embedded in Mn vacancies at low concentration,while entered the interlayer of MnO_(2) at high concentration.The existence of Mn vacancies will resulting in the distortion of neighboring atoms,leading to the electronic delocalization,and thus enhancing the conductivity,pseudocapacitance and rate capability of MnO_(2).Accordingly,the specific capacitances of optimized 0.4 KMO,0.4 NaMO and 0.4 LiMO samples are enhanced about 1.9,1.6 and 1.6 times compared to pure MnO_(2).Meanwhile,the rate performance has also been improved about 76%,46%and 42%,respectively.Theoretical calculations further confirm that the Mn vacancies can generate additional occupancy states and cause an increase in carrier concentration,which will improve the conductivity and further boost the pseudocapacitance of MnO_(2).This result open up a promising approach to explore active and durable electrode materials.
基金supported by the Shandong Provincial Natural Science Foundation(ZR2022ME179,ZR2021QE086)the Shandong Provincial Key Research and Development Program(Public Welfare Science and Technology Research)(2019GGX103010)+2 种基金the Science and Technology Planning Project of Higher School in Shandong Province(J18KA243)the Liaocheng Key Research and Development Program(Policy guidance category)(2022YDSF90)the Liaocheng University High-level Talents&PhD Research Startup Foundation(318051619)。
文摘Rational design of photocatalyst to maximize the use of sunlight is one of the issues to be solved in photocatalysis technology.In this study,the CuFe_(2)O_(4)@C/Cd_(0.9)Zn_(0.1)S(CFO@C/CZS)S-scheme photocatalyst with photothermal effect was synthesized by ultrasonic self-assembly combined with calcination.The dark CFO@C absorbed visible light and partly converted into heat to promote the hydrogen evolution reaction.The presence of heterojunctions inhibited the photogenerated electron-hole recombination.The graphite-carbon layer provided a stable channel for electron transfer,and the presence of magnetic CFO made recycle easier.Under the action of photothermal assistance and heterojunction,the hydrogen evolution rate of the optimal CFO@C/CZS was 80.79 mmol g^(-1) h^(-1),which was 2.55 times and 260.61 times of that of pure CZS and CFO@C,respectively.Notably,the composite samples also exhibit excellent stability and a wide range of environmental adaptability.Through experimental tests and first-principles simulation calculation methods,the plausible mechanism of photoactivity enhancement was proposed.This work provided a feasible strategy of photothermal assistance for the development of heterojunction photocatalysts with distinctive hydrogen evolution.
基金supported by the National Natural Science Foundation of China (Grant Nos. 61154002 and 51078331)the China Postdoctoral Science Foundation(Grant No. 20090451471)the Natural Science Foundation of Zhejiang Province,China (Grant No. Z1110222)
文摘The combustion characteristics of styrene-butadiene-styrene （SBS） asphalt are studied by thermogravimetric analysis （TG/DTG） at four different heating rates. According to the saturates/aromatics/resins/asphaltenes （SARA） fractionation method, the combustion process of SBS asphalt can be divided by Gaussian peak fitting into three main stages： oil content release, resin pyrolysis, and asphaltene and char combustion. When the heating rate increases, the mass losses of the oil content and resin pyrolysis increase, and less asphaltenes are formed at a higher temperature. The activation energy values are calculated by the Coats-Redfern method to be in the range 61.6 kJ/mol-142.9 kJ/mol. The Popescu method is used for the kinetic analysis, and the result shows that the three stages of asphalt combustion can be explained by the sphere phase boundary reaction model, the second order chemical reaction model, nucleation, and its subsequent growth model, respectively.
基金supported by the National Natural Science Foundation of China(22005130,21925404,21902137,21991151,and 22021001)the National Key Research and Development Program of China(2019YFA0705400 and 2020YFB1505800)the Natural Science Foundation of Fujian Province of China(2021J01988)。
文摘Energy storage is an ever-growing global concern due to increased energy needs and resource exhaustion.Sodium-ion batteries(SIBs)have called increasing attention and achieved substantial progress in recent years owing to the abundance and even distribution of Na resources in the crust,and the predicted low cost of the technique.Nevertheless,SIBs still face challenges like lower energy density and inferior cycling stability compared to mature lithium-ion batteries(LIBs).Enhancing the electrochemical performance of SIBs requires an in-deep and comprehensive understanding of the improvement strategies and the underlying reaction mechanism elucidated by in situ techniques.In this review,commonly applied in situ techniques,for instance,transmission electron microscopy(TEM),Raman spectroscopy,X-ray diffraction(XRD),and X-ray absorption near-edge structure(XANES),and their applications on the representative cathode and anode materials with selected samples are summarized.We discuss the merits and demerits of each type of material,strategies to enhance their electrochemical performance,and the applications of in situ characterizations of them during the de/sodiation process to reveal the underlying reaction mechanism for performance improvement.We aim to elucidate the composition/structure-per formance relationship to provide guidelines for rational design and preparation of electrode materials toward high electrochemical performance.
基金Supported by Zhejiang Provincial Natural Science Foundation of China under Grant Nos Y5090150 and Y6100244the National Natural Science Foundation of China under Grant No 61007051.
文摘A refractive index(RI)sensor based on a cladding-etched thin-core single-mode fiber(TCSMF)sandwiched between two single-mode fibers is demonstrated.The experimental results show that the sensitivity,within the RI range of 1.333–1.340,is enhanced at least 6 times by etching.It increases with the surrounding RI and reaches 857.5 nm/RIU at RI of 1.3684,and it can be expected to be higher with the decrease of the cladding diameter of the TCSMF.
基金financially supported by the Shenzhen Science and Technology Research Grant(JCYJ20200109140416788)the Chemistry and Chemical Engineering Guangdong Laboratory(1922018)+1 种基金the National Key R&D Program of China(2020YFB0704500)the financial support from the China Scholarship Council(CSC)and the Australian Research Council(ARC)through an ARC project(ARC DP160102627 and ARC DP170101467)。
文摘Rechargeable zinc-air batteries(ZAB)with a high theoretical energy density of 1086 Wh kg^(-1),have received tremendous research attention.However,the practical application of ZABs is still limited by high polarization and poor energy efficiency(low power density)due to the sluggish 4 electrons(e^(-))/oxygen(O_(2))kinetics over the air electrode.Here,a noble-metal-free Fe Nx C electrocatalyst is developed via a onepot approach,which provides a high density of the oxygen reduction reaction(ORR)active site and facilitates the ORR kinetics.Accordingly,the as-assembled Zn-air battery displayed a low charge–discharge voltage gap of 0.71 V at 10 m A cm^(-2),a remarkable peak power density as high as 181.2 m W cm^(-2),as well as the long-term durability for hundreds of hours,among the top level of those reported previously.Our work provides a major boost for the practical application of Zn-air battery in the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.61006051 and 61177050)the Zhejiang Provincial Natural Science Foundation,China(Grant No.Y1110777)
文摘The influence of vacancy defect on the doping of silicon nanowires is systematically studied by the first-principles calculations. The atomic structures and electronic properties of vacancies and vacancy-boron （vacancy-phosphor） com- plexes in H-passivated silicon nanowire with a diameter of 2.3 nm are explored. The results of geometry optimization indicate that a central vacancy can exist stably, while the vacancy at the edge of the nanowire undergoes a local surface reconstruction, which results in the extradition of the vacancy out of the nanowire. Total-energy calculations indicate that the central vacancy tends to form a vacancy-dopant defect pair. Further analysis shows that n-type doping efficiency is strongly inhibited by the unintentional vacancy defect. In contrast, the vacancy defect has little effect on p-type doping. Our results suggest that the vacancy defect should be avoided during the growth and the fabrication of devices.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY14E080014)the National Natural Science Foundation ofChina(Grant Nos.61154002 and 51078331)
文摘Asphalt materials will be ignited and release significant toxic fumes within tunnel fires. Thus, combustion character- istics of asphalt materials used in road tunnel should be studied in order to limit such an adverse effect. In the present work we study the influence of limestone fillers on combustion characteristics of asphalt mortar by thermogravimetric and kinetic analysis. It is shown that the combustion of asphalt mortar is not just a linear superposition of asphalt and limestone. The limestone will increase the ignition point and the activation energy of the primary volatile release, and will catalyze the char formation from the primary volatile release. Kinetic analysis shows that the primary volatile release stage of asphalt mortar combustion can be explained by a three-dimensional diffusion model, the secondary volatile release and char combustion stage can be explained by a model under the assumption of random nucleation and nuclei growth, whereas the limestone decomposition stage appears to follow the one-dimensional phase boundary model.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0134600)the National Natural Science Foundation of China(Grant Nos.52272152,61674063,and 62074061)+2 种基金Shenzhen Science and Technology Innovation Committee(Grant No.JCYJ20210324142010030)the Natural Science Foundation of Hubei Province(Grant No.2022CFA031)Interdisciplinary Research Program of Huazhong University of Science and Technology(Grant No.5003110122)。
文摘The discovery and manipulation of topological Hall effect(THE),an abnormal magnetoelectric response mostly related to the Dzyaloshinskii–Moriya interaction(DMI),are promising for next-generation spintronic devices based on topological spin textures such as magnetic skyrmions.However,most skyrmions and THE are stabilized in a narrow temperature window either below or over room temperature with high critical current manipulation.It is still elusive and challenging to achieve large THE with both wide temperature window till room temperature and low critical current manipulation.Here,using controllable,naturally oxidized sub-20 and sub-10 nm 2D van der Waals room-temperature ferromagnetic Fe_(3)GaTe_(2-x)crystals,we report robust 2D skyrmion THE with ultrawide temperature window ranging in three orders of magnitude from 2 to 300 K,in combination with giant THE of~5.4μΩ·cm at 10 K and~0.15μΩ·cm at 300 K,which is 1–3 orders of magnitude larger than that of all known room-temperature 2D skyrmion systems.Moreover,room-temperature current-controlled THE is also realized with a low critical current density of~6.2×10^(5)A·cm^(-2).First-principles calculations unveil natural oxidation-induced highly enhanced 2D interfacial DMI reasonable for robust giant THE.This work paves the way to room-temperature electrically controlled 2D THE-based practical spintronic devices.
基金Project supported by the Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ23F040001)the National Natural Science Foundation of China(Grant No.12204446)+1 种基金the Public Welfare Technology Research Project of Zhejiang Province(Grant No.LGC22E050006)the Quzhou Science and Technology Project of China(Grant No.2022K104).
文摘Quasi-bound state in the continuum(QBIC)resonance is gradually attracting attention and being applied in Goos-Hänchen(GH)shift enhancement due to its high quality(Q)factor and superior optical confinement.Currently,symmetry-protected QBIC resonance is often achieved by breaking the geometric symmetry,but few cases are achieved by breaking the material symmetry.This paper proposes a dielectric compound grating to achieve a high Q factor and high-reflection symmetry-protectede QBIC resonance based on material asymmetry.Theoretical calculations show that the symmetry-protected QBIC resonance achieved by material asymmetry can significantly increase the GH shift up to-980 times the resonance wavelength,and the maximum GH shift is located at the reflection peak with unity reflectance.This paper provides a theoretical basis for designing and fabricating high-performance GH shift tunable metasurfaces/dielectric gratings in the future.
基金Supported by the National Natural Science Foundation of China under Grant No 10804097）, and the National Basic Research Program of China under Grant No 2006CB921403, and the Zhejiang Provincial Qian-Jiang-Ren-Cai Project of China under Grant No 2006R10025.
文摘A highly sensitive all-optical atomic magnetometer based on the magnetooptical effect which uses the advanced technique of single laser beam detection is reported and demonstrated experimentally. A sensitivity of 0.5pT/Hz^1/2 is obtained by analyzing the magnetic noise spectrum, which exceeds that of most traditional magnetometers. This kind of atomic magnetometer is very compact, has a low power consumption, and has a high theoretical sensitivity limit, which make it suitable for many applications.
基金Supported by the National High-Technology Research and Development Program of China under Grant No 2014AA041901the NSAF Foundation of National Natural Science Foundation of China under Grant No U1330134+1 种基金the Opening Project of Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques under Grant No 2012ADL02the National Natural Science Foundation of China under Grant No 61308024
文摘The wavelength-tunable rectangular mode-locking operation is demonstrated in an all-fiber laser based on semi- conductor saturable absorber mirror. As the dissipative soliton resonance signature, the pulse duration varies from 5SOps to 2.1 ns as a function o~ the increasing pump power. Correspondingly, the maximum pulse energy is 9.11 n3. Moreover, it is found that the wavelength tunable operation with a range of approximately 10 nm could be obtained by properly adjusting the polarization controllers. The characteristics of the rectangular pulses at different wavelengths are similar to each other. The demonstration of the wavelength tunable rectangular pulses would be beneficial to some applications for many fields such as spectroscopy and sensing research.
文摘A fiber-optic liquid-level sensor is proposed and experimentally demonstrated.It is a Mach–Zehnder interferometer(MZI)composed of a thin-core single-mode fiber(TCSMF)without coating sandwiched between two single-mode fibers(SMFs).The transmission spectrum properties of the MZI modified by liquid around the TCSMF are used for detecting the liquid level.It is found that the sensor exhibits an excellent linear relationship between the level and the shift of interference dip wavelength and its achieved sensitivities are 0.160 nm/mm and 0.288 nm/mm for liquid with an RI of 1.3330 and 1.3696,respectively.Employing the spectrum differential integration(SDI)method to analyze transmission spectra can increase the detecting resolution of the liquid level.Due to its advantages of an extremely easy fabrication process,high sensitivity and a large sensing range,the sensor is an ideal candidate for continuous liquid level sensing.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11005049 and 61006051)
文摘Based on first-principles calculations, the electronic and magnetic properties of undoped and Li-doped rutile TiO2 have been studied. The results demonstrate that a cation vacancy can arouse ferromagnetism in TiO2 and the magnetic moment mainly comes from p orbitals of O atoms around the Ti vacancy. However, the Ti vacancy under normal conditions is very difficult to form due to its high formation energy. Our calculations indicate that Li-doped TiO2 can reduce the formation energy while keeping the magnetism. The large magnetization energy indicates that Li-doped TiO2 is a promising room-temperature diluted magnetic semiconductor.
