The chromium oxide materials were prepared using Cr2O3 micropowder as main starting material, TiO2 micropowder as sintering aid, polyvinyl alcohol as binder, by a series of processes such as slurrying, spraying granul...The chromium oxide materials were prepared using Cr2O3 micropowder as main starting material, TiO2 micropowder as sintering aid, polyvinyl alcohol as binder, by a series of processes such as slurrying, spraying granulation, machine moulding and cold isostatic pressing, and firing at 1 500 ℃ for 3 h in air （ oxygen partial pressure was 2. 1× 10^4 Pa ）, industrial nitrogen （ oxygen partial pressure was 1×10^3 Pa ） , pure nitrogen （ oxygen partial pressure was 10 Pa） , high purity nitrogen （ oxygen partial pressure was 0.1 Pa ） , and carbon cake embedded atmosphere （ oxygen partial pressure wtas 2.3×10-12 Pa ）. Effects of oxygen partial pressures on the sintering behavior of Cr2 O3 materials were investiga- ted. The results show that （ 1 ） for 3 wt% TiO2-doped specimeas, there is a substantial dependence of sintering on oxygen partial pressure （0. 1 Pa - 2. 1 ×10^4 Pa ） , and the bulk density increases and apparent porosity decreases with oxygen partial pressure decreasing; （2） even if the oxygen partial pressure is 0. 1 Pa, the specimen without TiO2 cannot reach densification sintering; （3） under very low oxygen partial pressure of carbon embedded atmosphere, Cr2O3 materials containing TiO2 or not can attain denzification.展开更多
Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the applicat...Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.展开更多
Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe ...Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe structural change by de/intercalation and diffusion of K^(+)ions with large ionic size,which results in not only much lower reversible capacity than the theoretical capacity but also poor power capability.Thus,it is important to enhance the structural stability of the layered-type TM oxides for outstanding electrochemical behaviors under the K-ion battery system.Herein,it is investigated that the substitution of the appropriate Ti^(4+)contents enables a highly enlarged reversible capacity of P3-type KxCrO_(2) using combined studies of first-principles calculation and various experiments.Whereas the pristine P3-type KxCrO_(2) just exhibits the reversible capacity of∼120 mAh g^(−1) in the voltage range of 1.5-4.0 V(vs.K^(+)/K),the∼0.61 mol K^(+)corresponding to∼150 mAh g^(−1) can be reversible de/intercalated at the structure of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) under the same conditions.Furthermore,even at the high current density of 788 mA g^(−1),the specific capacity of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) is∼120 mAh g^(−1),which is∼81 times larger than that of the pristine P3-type KxCrO_(2).It is believed that this research can provide an effective strategy to improve the electrochemical performances of the cathode materials suffered by severe structural change that occurred during charge/discharge under not only K-ion battery system but also other rechargeable battery systems.展开更多
A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free...A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free energy changes have been calculated and discussed.展开更多
Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anod...Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.展开更多
Spherical indium tin oxide （ITO） nanoparticles were synthesized by combustion method using citric acid as fuel and nitrates as oxidizer. The obtained ITO nanoparticles were characterized by TG-DSC, FT-IR, XRD, BET, ...Spherical indium tin oxide （ITO） nanoparticles were synthesized by combustion method using citric acid as fuel and nitrates as oxidizer. The obtained ITO nanoparticles were characterized by TG-DSC, FT-IR, XRD, BET, TEM, and SEM. The ITO nanoparticles grew steadily with the increase of heat treatment temperature, and the 700~C calcined particles had a crystallite size of 25.3 nm and a specific surface area of 26.1 m2.g i The avoidance of chlorine ions in the synthesis process decreases particle agglomeration and promotes powder densification. The 900~C sintered pellet had a density of 67.6% of theoretical density （TD） and increased steadily to 97.3% for the 1400℃ sintered ceramics, respectively.展开更多
According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide（C_2O）.Using density functional theory（DFT）, C_2O is found to be a direct gap semiconductor. In additi...According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide（C_2O）.Using density functional theory（DFT）, C_2O is found to be a direct gap semiconductor. In addition, we obtain the absorption spectra of the periodic structure of C_2O, which show optical anisotropy. To study the optical properties of C_2O nanostructures, time-dependent density functional theory（TDDFT） is used. The C_2O nanostructure has a strong absorption near 7 eV when the incident light polarizes along the armchair-edge. Besides, we find that the optical properties can be controlled by the edge configuration and the size of the C_2O nanostructure. With the elongation strain increasing, the range of light absorption becomes wider and there is a red shift of absorption spectrum.展开更多
Two different morphologies of ZnO（lotus-shaped, rod-shaped） and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy（SEM） a...Two different morphologies of ZnO（lotus-shaped, rod-shaped） and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. Fourier transform infrared spectroscopy（FT-IR）, thermal gravimetry（TG）, and X-ray diffraction（XRD） were also used to characterize the chemical structures and phase composites of ZnO and ZnO/PVDF composite materials. Breakdown voltage, dielectric constant and dielectric loss of ZnO/PVDF composite materials were also tested. Microstructure analysis showed that ZnO nanoparticles dispersed uniformly in the matrix. And the dielectric constant expresses a significantly improvement while the dielectric loss and breakdown voltage expresses no significant change. Moreover, dielectric constant keeps an improvement tendency with increasing content of ZnO.展开更多
Eu-doped ZnO nanosheets were synthesized successfully by means of the hydrothermal method. The X-ray diffraction（XRD） pattern shows that the sample is a single phase with the ZnO-like wurtzite structure. And the X-r...Eu-doped ZnO nanosheets were synthesized successfully by means of the hydrothermal method. The X-ray diffraction（XRD） pattern shows that the sample is a single phase with the ZnO-like wurtzite structure. And the X-ray photoelectron spectrum suggests that there are Eu3＋ ions in the matrix of the sample. Eu3＋-related red emissions resulted from energy transfer were observed for the nanosheets under UV laser excitation. The UV, green and yellow emissions were also seen in the photoluminescence spectra.展开更多
This work introduces the facile hydrothermal synthesis of double perovskite La2CuCoO6.X-ray diffraction pattern confirmed the formation of a monoclinic phase with P121/c1 symmetry.Transmission electron microscopy resu...This work introduces the facile hydrothermal synthesis of double perovskite La2CuCoO6.X-ray diffraction pattern confirmed the formation of a monoclinic phase with P121/c1 symmetry.Transmission electron microscopy results revealed that the self-assembled porous rods were composed of nanocrystallite aggregates.The estimated specific surface area of these mesoporous rods with an average pore diameter of 6 nm was^41 m^2·g^–1.The presence of ions with oxidation states of La^3+,Cu^2+,and Co^2+/Co^3+on the surface of the mesoporous La2CuCoO6 rods was confirmed by X-ray photoelectron spectroscopic analysis.Via cyclicvoltammetry and chronopotentiometry,the electrode fabricated from the mesoporous La2CuCoO6 rods were found to exhibit pseudocapacitive behavior with a specific capacitance of 259.4 F·g^–1 at a current density of 0.5 A·g^–1.An^89%retention in specific capacitance was achieved after 1000 charge/discharge cycles at a constant current density of4 A·g^–1.展开更多
NanocrystallineCuo5Zno5Fe2-xAlxO2（x=0.0,0.1,0.2,0.3,0.45 and 0.5） ferrite materials were synthesized using standard solid state reaction technique. The effects of Al3＋ contents on the structural, electrical, and ma...NanocrystallineCuo5Zno5Fe2-xAlxO2（x=0.0,0.1,0.2,0.3,0.45 and 0.5） ferrite materials were synthesized using standard solid state reaction technique. The effects of Al3＋ contents on the structural, electrical, and magnetic properties were investigated. Single phase cubic spinel structure was revealed by X-ray diffraction analysis. The crystallite size was evaluated considering the most intense diffraction peak （311） using Scherrer formula. Lattice constant decreased, whereas porosity increased with the increase in Al3＋ concentration. The value of saturation magnetization decreased with increasing aluminum contents. Temperature dependent value of direct current electrical resistivity has been determined. It is observed that the substitution of Al3＋ has significant impact on the dielectric constant, tangent of dielectric loss angle and dielectric loss factor. The variation in dielectric properties was attributed to space charge polarization.展开更多
1 Introduction As environmental pollution continues to worsen,governments are increasing their efforts to develop green transport vehicles,such as electric vehicles and hybrid cars.
Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nan...Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder（34.85 A·m^2·kg^–1） was markedly lower than that of the Fe3O4 powder（79.55 A·m^2·kg^–1）, which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.展开更多
Lithium-ion hybrid supercapacitors （LIHSs）, also called Li-ion capacitors, are electrochemical energy stor- age devices that combining the advantages of high power density of supercapacitor and high energy density o...Lithium-ion hybrid supercapacitors （LIHSs）, also called Li-ion capacitors, are electrochemical energy stor- age devices that combining the advantages of high power density of supercapacitor and high energy density of Li-ion battery. However, high power density and long cycle life are still challenges for the cul~ rent LIHSs due to the imbalance of charge-storage capacity and electrode kinetics between capacitor-type cathode and battery-type anode. Therefore, great efforts have been made on designing novel cathode materials with high storage capacity and anode material with enhanced kinetic behavior for LIHSs. With unique two-dimensional form and numerous appealing properties, for the past several years, the rational designed graphene and its composites materials exhibit greatly improved electrochemical performance as cathode or anode for LIHSs. Here, we summarized and discussed the latest advances of the state- of-art graphene-based materials for LIHSs applications. The major roles of graphene are highlighted as （1） a superior active material, （2） ultrathin 2D flexible support to remedy the sluggish reaction of the metal compound anode, and （3） good 2D building blocks for constructing macroscopic 3D pOFOUS car- bonjgraphene hybrids. In addition, some high performance aqueous LIHSs using graphene as electrode were also summarized. Finally, the perspectives and challenges are also proposed for further develop- ment of more advanced graphene-based LIHSs.展开更多
We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 in...We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent throughpore anodic aluminum oxide（AAO） membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 m A and 56% at 100 m A compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.展开更多
ZnO tetrapods were synthesized by a typical thermal vapor-solid deposition method in a horizontal tube furnace.Structural characterization was carried out by transmission electron microscopy （TEM） and select-area el...ZnO tetrapods were synthesized by a typical thermal vapor-solid deposition method in a horizontal tube furnace.Structural characterization was carried out by transmission electron microscopy （TEM） and select-area electron diffraction （SAED）,which shows the presence of zinc blende nucleus in the center of tetrapods while the four branches taking hexagonal wurtzite structure.The electrical transport property of ZnO tetrapods was investigated through an in-situ nanoprobe system.The three branches of a tetrapod serve as source,drain,and ＂gate＂,respectively;while the fourth branch pointing upward works as the force trigger by vertically applying external force downward.The conductivity of each branch of ZnO-tetrapods increases 3-4 times under pressure.In such situation,the electrical current through the branches of ZnO tetrapods can be tuned by external force,and therefore a simple force sensor based on ZnO tetrapods has been demonstrated for the first time.展开更多
We report a simple solution-processed method for the fabrication of low-cost,flexible optical limiting materials based on graphene oxide(GO) impregnated polyvinyl alcohol(PVA) sheets.Such GO–PVA composite sheets disp...We report a simple solution-processed method for the fabrication of low-cost,flexible optical limiting materials based on graphene oxide(GO) impregnated polyvinyl alcohol(PVA) sheets.Such GO–PVA composite sheets display highly efficient broadband optical limiting activities for femtosecond laser pulses at 400,800,and 1400 nm with very low limiting thresholds.Femtosecond pump–probe measurement results revealed that nonlinear absorption played an important role for the observed optical limiting activities.High flexibility and efficient optical limiting activities of these materials allow these composite sheets to be attached to nonplanar optical sensors in order to protect them from light-induced damage.展开更多
Magnetically responsive composite materials have been used in interesting applications in various areas of bioscience, biotechnology, and environmental technology. In this work, a simple method to determine the amount...Magnetically responsive composite materials have been used in interesting applications in various areas of bioscience, biotechnology, and environmental technology. In this work, a simple method to determine the amount of magnetic iron oxide nano- and microparticles attached to magnetically-modified partic- ulate diamagnetic materials has been developed using a commercially available magnetic permeability meter, The procedure is fast and enables dry particulate magnetically modified materials to be analysed without any modification or pretreatment. We show that the magnetic permeability can be measured for materials containing up to 20% magnetic iron oxide, The magnetic permeability measurements are highly reproducible.展开更多
Transparent conductive indium tin oxide （ITO） nanoparticles were synthesized by a novel sol-gel method. Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid. A sol-gel process wa...Transparent conductive indium tin oxide （ITO） nanoparticles were synthesized by a novel sol-gel method. Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid. A sol-gel process was induced when tertiary butyl alcohol was added dropwise to the above solution. ITO nanopartides with an average crystallite size of 18.5 nm and surface area of 32.6 m^2 ]g were obtained after the gel was heat-treated at 700 ℃, The ITO nanoparticles showed good sinterability, the starting sintering temperature decreased sharply to 900 ℃, and the 1400 ℃ sintered pellet had a density of 98.1% of theoretical density （TD）.展开更多
The exploration for post-carbon electrode ma- terials for lithium-ion batteries has been a crucial way to satisfy the ever-growing demands for better performance with higher energy/power densities, enhanced safety, an...The exploration for post-carbon electrode ma- terials for lithium-ion batteries has been a crucial way to satisfy the ever-growing demands for better performance with higher energy/power densities, enhanced safety, and longer cycle life. Transition metal oxides have recently re- ceived a great deal of attention as very promising anode materials due to their high theoretical capacity, good safety, eco-benignity, and huge abundance. The present work re- views the latest advances in developing novel transition metal oxides, including FeeO3, Fe3O4, CO3O4, CoO, NiO, MnO, Mn203, Mn3O4, MnO2, MOO3, Cr2O3, Nb2O5, and some binary oxides such as NiCO2O4, ZnCO2O4, MnCO2O4 and CoMn2O4. Nanostructuring and hybrid strategies ap- plicable to transition metal oxides are summarized and analyzed. Furthermore, the impacts of binder choice and heat treatment on electrochemical performance are discussed.展开更多
文摘The chromium oxide materials were prepared using Cr2O3 micropowder as main starting material, TiO2 micropowder as sintering aid, polyvinyl alcohol as binder, by a series of processes such as slurrying, spraying granulation, machine moulding and cold isostatic pressing, and firing at 1 500 ℃ for 3 h in air （ oxygen partial pressure was 2. 1× 10^4 Pa ）, industrial nitrogen （ oxygen partial pressure was 1×10^3 Pa ） , pure nitrogen （ oxygen partial pressure was 10 Pa） , high purity nitrogen （ oxygen partial pressure was 0.1 Pa ） , and carbon cake embedded atmosphere （ oxygen partial pressure wtas 2.3×10-12 Pa ）. Effects of oxygen partial pressures on the sintering behavior of Cr2 O3 materials were investiga- ted. The results show that （ 1 ） for 3 wt% TiO2-doped specimeas, there is a substantial dependence of sintering on oxygen partial pressure （0. 1 Pa - 2. 1 ×10^4 Pa ） , and the bulk density increases and apparent porosity decreases with oxygen partial pressure decreasing; （2） even if the oxygen partial pressure is 0. 1 Pa, the specimen without TiO2 cannot reach densification sintering; （3） under very low oxygen partial pressure of carbon embedded atmosphere, Cr2O3 materials containing TiO2 or not can attain denzification.
基金the Fundamental Research Funds for the Central Universities,China(No.06500177)the National Natural Science Foundation of China Joint Fund Project(No.U1764255)。
文摘Layered oxide is a promising cathode material for sodium-ion batteries because of its high-capacity,high operating voltage,and simple synthesis.Cycling performance is an important criterion for evaluating the application prospects of batteries.However,facing challenges,including phase transitions,ambient stability,side reactions,and irreversible anionic oxygen activity,the cycling performance of layered oxide cathode materials still cannot meet the application requirements.Therefore,this review proposes several strategies to address these challenges.First,bulk doping is introduced from three aspects:cationic single doping,anionic single doping,and multi-ion doping.Second,homogeneous surface coating and concentration gradient modification are reviewed.In addition,methods such as mixed structure design,particle engineering,high-entropy material construction,and integrated modification are proposed.Finally,a summary and outlook provide a new horizon for developing and modifying layered oxide cathode materials.
基金Korea Institute of Materials Science,Grant/Award Number:PNK9370National Research Foundation of Korea,Grant/Award Numbers:NRF-2021R1A2C1014280,NRF-2022R1C1C1011058,NRF-2022M3H446401037201Korea Institute of Science and Technology,Grant/Award Number:2E32581-23-092。
文摘Layered-type transition metal(TM)oxides are considered as one of the most promising cathodes for K-ion batteries because of the large theoretical gravimetric capacity by low molar mass.However,they suffer from severe structural change by de/intercalation and diffusion of K^(+)ions with large ionic size,which results in not only much lower reversible capacity than the theoretical capacity but also poor power capability.Thus,it is important to enhance the structural stability of the layered-type TM oxides for outstanding electrochemical behaviors under the K-ion battery system.Herein,it is investigated that the substitution of the appropriate Ti^(4+)contents enables a highly enlarged reversible capacity of P3-type KxCrO_(2) using combined studies of first-principles calculation and various experiments.Whereas the pristine P3-type KxCrO_(2) just exhibits the reversible capacity of∼120 mAh g^(−1) in the voltage range of 1.5-4.0 V(vs.K^(+)/K),the∼0.61 mol K^(+)corresponding to∼150 mAh g^(−1) can be reversible de/intercalated at the structure of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) under the same conditions.Furthermore,even at the high current density of 788 mA g^(−1),the specific capacity of P3-type K0.71[Cr_(0.75)Ti_(0.25)]O_(2) is∼120 mAh g^(−1),which is∼81 times larger than that of the pristine P3-type KxCrO_(2).It is believed that this research can provide an effective strategy to improve the electrochemical performances of the cathode materials suffered by severe structural change that occurred during charge/discharge under not only K-ion battery system but also other rechargeable battery systems.
基金This work was supported by Postdoctoral Foundation of Northwestern Polytechnical University and Science Research FOundation o
文摘A thermodynamic model has been built up for the interactions between molten Ti alloys and oxide molding materials in the way of decomposition and solution of molding materials, then the influences on the reaction free energy changes have been calculated and discussed.
基金supported by the Natural Science Foundation of China(5207123251871165)。
文摘Understanding the crystal phase evolution of bimetallic oxide anodes is the main concern to profoundly reveal the conversion reaction kinetics and sodium-ion storage mechanisms.Herein,an integrated selfsupporting anode of the Cu-decorated Cu-Mn bimetallic oxides with oxygen vacancies(Ov-BMO-Cu)are in-situ generated by phase separation and hydrogen etching using nanoporous Cu-Mn alloy as selfsacrificial templates.On this basis,we have elucidated the relationship between the phase evolution,oxygen vacancies and sodium-ion storage mechanisms,further demonstrating the evolution of oxygen vacancies and the inhibition effect of manganese oxides as an“anchor”on grain aggregation of copper oxides.The kinetic analyses confirm that the expanded lattice space and increased oxygen vacancies of cycled Ov-BMO-Cu synergistically guarantee effective sodium-ion diffusion and storage mechanisms.Therefore,the Ov-BMO-Cu electrode exhibits higher reversible capacities of 4.04 mA h cm^(-2)at 0.2 mA cm^(-2)after 100 cycles and 2.20 m A h cm^(-2)at 1.0 mA cm^(-2)after 500 cycles.Besides,the presodiated Ov-BMO-Cu anode delivers a considerable reversible capacity of 0.79 m A h cm^(-2)at 1.0 mA cm^(-2)after 60 cycles in full cells with Na_(3)V_(2)(PO_(4))_(3)cathode,confirming its outstanding practicality.Thus,this work is expected to provide enlightenment for designing high-capacity bimetallic oxide anodes.
文摘Spherical indium tin oxide （ITO） nanoparticles were synthesized by combustion method using citric acid as fuel and nitrates as oxidizer. The obtained ITO nanoparticles were characterized by TG-DSC, FT-IR, XRD, BET, TEM, and SEM. The ITO nanoparticles grew steadily with the increase of heat treatment temperature, and the 700~C calcined particles had a crystallite size of 25.3 nm and a specific surface area of 26.1 m2.g i The avoidance of chlorine ions in the synthesis process decreases particle agglomeration and promotes powder densification. The 900~C sintered pellet had a density of 67.6% of theoretical density （TD） and increased steadily to 97.3% for the 1400℃ sintered ceramics, respectively.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0303600)the National Natural Science Foundation of China(Grant Nos.11474207 and 11374217)
文摘According to first principle simulations, we theoretically predict a type of stable single-layer graphene oxide（C_2O）.Using density functional theory（DFT）, C_2O is found to be a direct gap semiconductor. In addition, we obtain the absorption spectra of the periodic structure of C_2O, which show optical anisotropy. To study the optical properties of C_2O nanostructures, time-dependent density functional theory（TDDFT） is used. The C_2O nanostructure has a strong absorption near 7 eV when the incident light polarizes along the armchair-edge. Besides, we find that the optical properties can be controlled by the edge configuration and the size of the C_2O nanostructure. With the elongation strain increasing, the range of light absorption becomes wider and there is a red shift of absorption spectrum.
基金Funded by the National Natural Science Foundation of China(51677045)the Natural Science Foundation of Heilongjiang Province of China(E201224)
文摘Two different morphologies of ZnO（lotus-shaped, rod-shaped） and ZnO/PVDF composite materials were prepared. The morphologies of ZnO and composite materials were characterized by scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. Fourier transform infrared spectroscopy（FT-IR）, thermal gravimetry（TG）, and X-ray diffraction（XRD） were also used to characterize the chemical structures and phase composites of ZnO and ZnO/PVDF composite materials. Breakdown voltage, dielectric constant and dielectric loss of ZnO/PVDF composite materials were also tested. Microstructure analysis showed that ZnO nanoparticles dispersed uniformly in the matrix. And the dielectric constant expresses a significantly improvement while the dielectric loss and breakdown voltage expresses no significant change. Moreover, dielectric constant keeps an improvement tendency with increasing content of ZnO.
基金Supported by the National Natural Science Foundation of China(Nos.60778040 60878039)+7 种基金the Program for the Development of Science and Technology of Jilin ProvinceChina(Nos.20090140 20090331)the Eleventh Five-Year Program for Science and Technology of Education Department of Jilin Province China(No.20090422)the Open Project Program of National Laboratory of Superhard Materials of China(No.201004)the Program for the Master Students’ Scientific and Innovative Research of Jilin Normal University China(No.S09010104)
文摘Eu-doped ZnO nanosheets were synthesized successfully by means of the hydrothermal method. The X-ray diffraction（XRD） pattern shows that the sample is a single phase with the ZnO-like wurtzite structure. And the X-ray photoelectron spectrum suggests that there are Eu3＋ ions in the matrix of the sample. Eu3＋-related red emissions resulted from energy transfer were observed for the nanosheets under UV laser excitation. The UV, green and yellow emissions were also seen in the photoluminescence spectra.
基金the financial support of the Council of Scientific and Industrial Research(CSIR),New Delhi(India)(F.No.22(0778)/18/EMR-II).
文摘This work introduces the facile hydrothermal synthesis of double perovskite La2CuCoO6.X-ray diffraction pattern confirmed the formation of a monoclinic phase with P121/c1 symmetry.Transmission electron microscopy results revealed that the self-assembled porous rods were composed of nanocrystallite aggregates.The estimated specific surface area of these mesoporous rods with an average pore diameter of 6 nm was^41 m^2·g^–1.The presence of ions with oxidation states of La^3+,Cu^2+,and Co^2+/Co^3+on the surface of the mesoporous La2CuCoO6 rods was confirmed by X-ray photoelectron spectroscopic analysis.Via cyclicvoltammetry and chronopotentiometry,the electrode fabricated from the mesoporous La2CuCoO6 rods were found to exhibit pseudocapacitive behavior with a specific capacitance of 259.4 F·g^–1 at a current density of 0.5 A·g^–1.An^89%retention in specific capacitance was achieved after 1000 charge/discharge cycles at a constant current density of4 A·g^–1.
文摘NanocrystallineCuo5Zno5Fe2-xAlxO2（x=0.0,0.1,0.2,0.3,0.45 and 0.5） ferrite materials were synthesized using standard solid state reaction technique. The effects of Al3＋ contents on the structural, electrical, and magnetic properties were investigated. Single phase cubic spinel structure was revealed by X-ray diffraction analysis. The crystallite size was evaluated considering the most intense diffraction peak （311） using Scherrer formula. Lattice constant decreased, whereas porosity increased with the increase in Al3＋ concentration. The value of saturation magnetization decreased with increasing aluminum contents. Temperature dependent value of direct current electrical resistivity has been determined. It is observed that the substitution of Al3＋ has significant impact on the dielectric constant, tangent of dielectric loss angle and dielectric loss factor. The variation in dielectric properties was attributed to space charge polarization.
基金supported by the National Science Foundation of China(51502009,51532001,21675109)the National Key Basic Research Program of China(2014CB31802)the Science Foundation of Henan province(162300410209)
文摘1 Introduction As environmental pollution continues to worsen,governments are increasing their efforts to develop green transport vehicles,such as electric vehicles and hybrid cars.
基金the National Natural Science Foundation of China (No.51274039)the State Key Lab of Advanced Metals and Materials (No.2013-ZD05)the Guangdong Foundation of Research (No.2014B090901003)
文摘Fe3O4@SiO2 core–shell composite nanoparticles were successfully prepared by a one-pot process. Tetraethyl-orthosilicate was used as a surfactant to synthesize Fe3O4@SiO2 core–shell structures from prepared Fe3O4 nanoparticles. The properties of the Fe3O4 and Fe3O4@SiO2 composite nanoparticles were studied by X-ray diffraction, transmission electron microscopy, energy dispersive spectroscopy, and Fourier transform infrared spectroscopy. The prepared Fe3O4 particles were approximately 12 nm in size, and the thickness of the SiO2 coating was approximately 4 nm. The magnetic properties were studied by vibrating sample magnetometry. The results show that the maximum saturation magnetization of the Fe3O4@SiO2 powder（34.85 A·m^2·kg^–1） was markedly lower than that of the Fe3O4 powder（79.55 A·m^2·kg^–1）, which demonstrates that Fe3O4 was successfully wrapped by SiO2. The Fe3O4@SiO2 composite nanoparticles have broad prospects in biomedical applications; thus, our next study will apply them in magnetic resonance imaging.
基金supported by the National Nature Science Foundations of China(Grant No.21673263,21573265)the Independent Innovation Plan Foundations of Qingdao City of China(Grant No.16-5-1-42-jch)the western Young Scholars Foundations of Chinese Academy of Sciences
文摘Lithium-ion hybrid supercapacitors （LIHSs）, also called Li-ion capacitors, are electrochemical energy stor- age devices that combining the advantages of high power density of supercapacitor and high energy density of Li-ion battery. However, high power density and long cycle life are still challenges for the cul~ rent LIHSs due to the imbalance of charge-storage capacity and electrode kinetics between capacitor-type cathode and battery-type anode. Therefore, great efforts have been made on designing novel cathode materials with high storage capacity and anode material with enhanced kinetic behavior for LIHSs. With unique two-dimensional form and numerous appealing properties, for the past several years, the rational designed graphene and its composites materials exhibit greatly improved electrochemical performance as cathode or anode for LIHSs. Here, we summarized and discussed the latest advances of the state- of-art graphene-based materials for LIHSs applications. The major roles of graphene are highlighted as （1） a superior active material, （2） ultrathin 2D flexible support to remedy the sluggish reaction of the metal compound anode, and （3） good 2D building blocks for constructing macroscopic 3D pOFOUS car- bonjgraphene hybrids. In addition, some high performance aqueous LIHSs using graphene as electrode were also summarized. Finally, the perspectives and challenges are also proposed for further develop- ment of more advanced graphene-based LIHSs.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61204049 and 51402366)Guangdong Natural Science Foundation,China(Grant No.S2012040007363)Foundation for Distinguished Young Talents in Higher Education of Guangdong,China(Grant Nos.2012LYM 0058 and2013LYM 0022)
文摘We report an effective enhancement in light extraction of Ga N-based light-emitting diodes（LEDs） with an Al-doped Zn O（AZO） transparent conductive layer by incorporating a top regular textured SiO2 layer. The 2 inch transparent throughpore anodic aluminum oxide（AAO） membrane was fabricated and used as the etching mask. The periodic pore with a pitch of about 410 nm was successfully transferred to the surface of the SiO2 layer without any etching damages to the AZO layer and the electrodes. The light output power was enhanced by 19% at 20 m A and 56% at 100 m A compared to that of the planar LEDs without a patterned surface. This approach offers a technique to fabricate a low-cost and large-area regular pattern on the LED chip for achieving enhanced light extraction without an obvious increase of the forward voltage.
基金supported by the China Scholarship Council (CSC) (No.20083019)Fundamental Research Funds for the Central Universities (Nos.21611603,21611424,and 216113143)+1 种基金Jinan University Start-up Funds (No.50624019)the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KJCX2-YW-M13)
文摘ZnO tetrapods were synthesized by a typical thermal vapor-solid deposition method in a horizontal tube furnace.Structural characterization was carried out by transmission electron microscopy （TEM） and select-area electron diffraction （SAED）,which shows the presence of zinc blende nucleus in the center of tetrapods while the four branches taking hexagonal wurtzite structure.The electrical transport property of ZnO tetrapods was investigated through an in-situ nanoprobe system.The three branches of a tetrapod serve as source,drain,and ＂gate＂,respectively;while the fourth branch pointing upward works as the force trigger by vertically applying external force downward.The conductivity of each branch of ZnO-tetrapods increases 3-4 times under pressure.In such situation,the electrical current through the branches of ZnO tetrapods can be tuned by external force,and therefore a simple force sensor based on ZnO tetrapods has been demonstrated for the first time.
基金financial support from the Guangdong Innovative Research Team Program of China (201101C0105067115)DSTA Singapore (Project DSTA-NUS-DIRP/9010100347)National Research Foundation Singapore (R398-001-062-281)
文摘We report a simple solution-processed method for the fabrication of low-cost,flexible optical limiting materials based on graphene oxide(GO) impregnated polyvinyl alcohol(PVA) sheets.Such GO–PVA composite sheets display highly efficient broadband optical limiting activities for femtosecond laser pulses at 400,800,and 1400 nm with very low limiting thresholds.Femtosecond pump–probe measurement results revealed that nonlinear absorption played an important role for the observed optical limiting activities.High flexibility and efficient optical limiting activities of these materials allow these composite sheets to be attached to nonplanar optical sensors in order to protect them from light-induced damage.
文摘Magnetically responsive composite materials have been used in interesting applications in various areas of bioscience, biotechnology, and environmental technology. In this work, a simple method to determine the amount of magnetic iron oxide nano- and microparticles attached to magnetically-modified partic- ulate diamagnetic materials has been developed using a commercially available magnetic permeability meter, The procedure is fast and enables dry particulate magnetically modified materials to be analysed without any modification or pretreatment. We show that the magnetic permeability can be measured for materials containing up to 20% magnetic iron oxide, The magnetic permeability measurements are highly reproducible.
基金supported by grants from Ph.D. Programs Foundation of Ministry of Education of China (200802511022)National Natural Science Foundation of China (50902049)
文摘Transparent conductive indium tin oxide （ITO） nanoparticles were synthesized by a novel sol-gel method. Granulated indium and tin were dissolved in HNO3 and partially complexed with citric acid. A sol-gel process was induced when tertiary butyl alcohol was added dropwise to the above solution. ITO nanopartides with an average crystallite size of 18.5 nm and surface area of 32.6 m^2 ]g were obtained after the gel was heat-treated at 700 ℃, The ITO nanoparticles showed good sinterability, the starting sintering temperature decreased sharply to 900 ℃, and the 1400 ℃ sintered pellet had a density of 98.1% of theoretical density （TD）.
基金supported by the National Basic Research Program of China(2013CB934103)the National Natural Science Foundation of China(21173054)Science & Technology Commission of Shanghai Municipality(08DZ2270500)
文摘The exploration for post-carbon electrode ma- terials for lithium-ion batteries has been a crucial way to satisfy the ever-growing demands for better performance with higher energy/power densities, enhanced safety, and longer cycle life. Transition metal oxides have recently re- ceived a great deal of attention as very promising anode materials due to their high theoretical capacity, good safety, eco-benignity, and huge abundance. The present work re- views the latest advances in developing novel transition metal oxides, including FeeO3, Fe3O4, CO3O4, CoO, NiO, MnO, Mn203, Mn3O4, MnO2, MOO3, Cr2O3, Nb2O5, and some binary oxides such as NiCO2O4, ZnCO2O4, MnCO2O4 and CoMn2O4. Nanostructuring and hybrid strategies ap- plicable to transition metal oxides are summarized and analyzed. Furthermore, the impacts of binder choice and heat treatment on electrochemical performance are discussed.
