We describes a controllable synthesis procedure for growing a-Ee2O3 and Ee3O4 nanowires. High magnetic hematite a-Fe2O3 nanowires are successfully grown on Fe0.5Ni0.5 alloy substrates via an oxide assisted vapor-solid...We describes a controllable synthesis procedure for growing a-Ee2O3 and Ee3O4 nanowires. High magnetic hematite a-Fe2O3 nanowires are successfully grown on Fe0.5Ni0.5 alloy substrates via an oxide assisted vapor-solid process. Experimental results also indicate that previous immersion of the substrates in a solution of oxalic acid causes the grown nanowires to convert gradually into magnetite （Fe3O4） nanowires. Additionally, the saturated state of Fe3O4 nanowires is achieved as the oxalic acid concentration reaches 0.75 mol/L. The average diameter and length of nanowires expands with an increasing operation temperature and the growth density of nanowires accumulates with an increasing gas flux in the vapor-solid process. The growth mechanism of a-Fe2O3 and Fe3O4 nanowires is also discussed. The results demonstrate that the entire synthesis of nanowires can be completed within 2 h.展开更多
Uniform a-Fe203/amorphous TiO2 core-shell nanocomposites were prepared via a hydrolysis method anda-Fe2OJanatase TiO2 core-shell nanocomposites were obtained via a post-calcination process. The structure andmorphology...Uniform a-Fe203/amorphous TiO2 core-shell nanocomposites were prepared via a hydrolysis method anda-Fe2OJanatase TiO2 core-shell nanocomposites were obtained via a post-calcination process. The structure andmorphology of the products were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy,transmission electron microscopy and scanning electron microscopy. Amorphous TiO2 nanoparticles with diametersof ten to several tens nanometer were formed on the surface of a-Fe203 nanoparticles and the coverage density of thesecondary TiO2 nanoparticles in the composite can be controlled by varying the concentration of Ti（BuO）4 m theethanol solution. The visible-light photocatalytic properties of different products towards Rhodamine B（RhB） wereinvestigated. The results show that the a-Fe203/amorphous TiO2 exhibits a good photocatalytic property owing to theextension of the light response range to visible light and the efficient separation of photogenerated electrons and holesbetween a-Fe203 and amorphous TiO2.展开更多
Bio-template method has recently attracted much attention because of its prominent advantages in obtai-ning morphology controlled materials with structural specificity, complexity and their unique functions. The bio-t...Bio-template method has recently attracted much attention because of its prominent advantages in obtai-ning morphology controlled materials with structural specificity, complexity and their unique functions. The bio-template method combining with electrochemical deposition was employed to synthesize spirulina/hematite composite microstructures using native spirulina as template. A great amount of hematite（a-Fe2O3） nanoparticles can be formed and deposited onto the spirulina, resulting in a robust and pseudo-homogeneous surface. And the spinth- na/a-Fe2O3 composite exhibits an improved surface wettability due to its helical morphology. This facile strategy may open new horizons in the field of replicating specific biological structures for functional materials in other potential applications.展开更多
Hematite (α-Fe2O3) nanopowder was synthesized from 0.1 mol·L-1 FeCl3 solution by sonochemical hydrolysis method, and characterized by X-ray diffraction (XRD), transmission electron micrograph (TEM), Fourier tran...Hematite (α-Fe2O3) nanopowder was synthesized from 0.1 mol·L-1 FeCl3 solution by sonochemical hydrolysis method, and characterized by X-ray diffraction (XRD), transmission electron micrograph (TEM), Fourier transform infrared (FTIR), Fourier transform Raman (FT-Raman) and X-ray photoelectron spectroscopy (XPS). The results showed that the spherical, well-dispersed α-Fe2O3 nanopowder was obtained with the average size of 20 nm. The possible mechanism for the formation of α-Fe2O3 nanoparticals was also discussed.展开更多
In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S）...In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S） on the magnetic properties and magnetic reversal modes are systematically analyzed. As S increases from 1 nm to 48 nm, the remanence （Jr） increases, while the coercivity （Hci） decreases, leading to the result that the magnetic energy prod- uct [（BH）max] first increases slowly, and then decreases rapidly, peaking at S = 24 nm with the （BH）max of 72.9 MGOe （1 MGOe = 7.95775 kJ.m-3）. Besides, with the increase of S, the coercivity mechanism of the nanocomposite magnet changes from nucleation to pinning. Furthermore, by observing the magnetic moment evolution in demagnetization pro- cess, the magnetic reversal of the soft phase in the nanocomposite magnet can be divided into three modes with the increase of S： coherent rotation （S 〈 3 nm）, quasi-coherent rotation （3 nm≤S 〈 36 nm）, and the vortex-like rotation （S ≥36 nm）.展开更多
We report a facile, two-step hydrothermal synthesis of a novel Co304/a-Fe2O3 branched nanowire heterostructure, which can serve as a good candidate for lithium-ion battery anodes with high Li＋ storage capacity and st...We report a facile, two-step hydrothermal synthesis of a novel Co304/a-Fe2O3 branched nanowire heterostructure, which can serve as a good candidate for lithium-ion battery anodes with high Li＋ storage capacity and stability. The single-crystalline, primary C0304 nanowire trunk arrays directly grown on Ti substrates allow for efficient electrical and ionic transport. The secondary a-Fe2O3 branches provide enhanced surface area and high theoretical Li＋ storage capacity, and can also serve as volume spacers between neighboring Co3O4 NW arrays to maintain electrolyte penetration as well as reduce the aggregation during Li＋ intercalation, thus leading to improved electrochemical energy storage performance.展开更多
Fiber-shaped energy storage devices are indispensable parts of wearable and portable electronics.Aqueous rechargeable Ni/Fe battery is a very appropriate energy storage device due to their good safety without organic ...Fiber-shaped energy storage devices are indispensable parts of wearable and portable electronics.Aqueous rechargeable Ni/Fe battery is a very appropriate energy storage device due to their good safety without organic electrolytes, high ionic conductivity, and low cost. Unfortunately, the low energy density,poor power density and cycling performance hinder its further practical applications. In this study, in order to obtain high performance negative iron-based material, we first synthesized a-iron oxide(α-Fe2O3) nanorods(NRs) with superstructures on the surface of highly conductive carbon nanotube fibers(CNTFs), then electrically conductive polypyrrole(PPy) was coated to enhance the electron, ion diffusion and cycle stability. The as-prepared α-Fe2O3@PPy NRs/CNTF electrode shows a high specific capacity of 0.62 Ah cm-3 at the current density of 1 A cm-3. Furthermore, the Ni/Fe battery that was assembled by the above negative electrode shows a maximum volumetric energy density of 15.47 mWh cm-3 with228.2 mW cm-3 at a current density of 1 A cm-3. The cycling durability and mechanical flexibility of the Ni/Fe battery were tested, which show good prospect for practical application. In summary, these merits make it possible for our Ni/Fe battery to have practical applications in next generation flexible energy storage devices.展开更多
CaC12 can be sprayed onto sinter surface, which can improve the low temperature reduction degradation index （RDI＋3.15） of sinter. This has been recognized; however, there are various opinions on the inhibition mech...CaC12 can be sprayed onto sinter surface, which can improve the low temperature reduction degradation index （RDI＋3.15） of sinter. This has been recognized; however, there are various opinions on the inhibition mechanism of it. At the same time, the corrosion of C1 element on equipment is very serious. First-principle calculations based on density functional theory were performed to investigate the binding mechanisms of calcium species on a a-Fe2 03 （0 0 1） surface. This is crucial in demonstrating the role of the CaC12 on improving the low temperature reduction degrada tion index. It has been determined that C1 could greatly increase the adsorption of the vacuum layer for the Ca/Fe2 03 system and the relaxation produced by adsorption made bond length decrease, bond energies increase and structure compact. Those are the main reasons that inhibiting the reduction disintegration of sinter.展开更多
High surface energy of high-index facets endows nanocrystals with high activities and thus promotes potential applications such as highly efficient catalysts,special optical,electrical and magnetic devices.But the hig...High surface energy of high-index facets endows nanocrystals with high activities and thus promotes potential applications such as highly efficient catalysts,special optical,electrical and magnetic devices.But the high surface energy of the high-index facets usually drives them to grow faster than the other facets and finally disappear during the crystal growth,which leads the synthesis of nanocrystals with high-indexed facets exposed to be a great challenge.Herein,we introduced two routes to control the synthesis of-Fe2O3polyhedrons with different sets of high-index facets,one using different metal ions(Ni2+,Cu2+or Zn2+)as structure-directing agents and the other applying polymer surfactant sodium carboxymethyl cellulose(CMC)as additive.The growth process of high-index-Fe2O3polyhedrons was also discussed and possible growth mechanism was proposed.展开更多
文摘We describes a controllable synthesis procedure for growing a-Ee2O3 and Ee3O4 nanowires. High magnetic hematite a-Fe2O3 nanowires are successfully grown on Fe0.5Ni0.5 alloy substrates via an oxide assisted vapor-solid process. Experimental results also indicate that previous immersion of the substrates in a solution of oxalic acid causes the grown nanowires to convert gradually into magnetite （Fe3O4） nanowires. Additionally, the saturated state of Fe3O4 nanowires is achieved as the oxalic acid concentration reaches 0.75 mol/L. The average diameter and length of nanowires expands with an increasing operation temperature and the growth density of nanowires accumulates with an increasing gas flux in the vapor-solid process. The growth mechanism of a-Fe2O3 and Fe3O4 nanowires is also discussed. The results demonstrate that the entire synthesis of nanowires can be completed within 2 h.
文摘Uniform a-Fe203/amorphous TiO2 core-shell nanocomposites were prepared via a hydrolysis method anda-Fe2OJanatase TiO2 core-shell nanocomposites were obtained via a post-calcination process. The structure andmorphology of the products were characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy,transmission electron microscopy and scanning electron microscopy. Amorphous TiO2 nanoparticles with diametersof ten to several tens nanometer were formed on the surface of a-Fe203 nanoparticles and the coverage density of thesecondary TiO2 nanoparticles in the composite can be controlled by varying the concentration of Ti（BuO）4 m theethanol solution. The visible-light photocatalytic properties of different products towards Rhodamine B（RhB） wereinvestigated. The results show that the a-Fe203/amorphous TiO2 exhibits a good photocatalytic property owing to theextension of the light response range to visible light and the efficient separation of photogenerated electrons and holesbetween a-Fe203 and amorphous TiO2.
基金Suppolted by the National Key R＆D Program of China（No.2016YFE0112100）, the EU H2020 Program（FabSurfWAR No.644971 NanoStencil No.767285）, the National Natural Science Foundation of China（Nos. 11504031）, 61604018）, the Science and Technology Program of Jilin Province, China（Nos.20160623002TC, 20160520101JH, 20180414002GH, 20180414081GIt and 20180520203JH）, the China Postdoctoral Science Foundation（No.2015M581377） and the ＂＇111＂ Project of China （No.D17017）.
文摘Bio-template method has recently attracted much attention because of its prominent advantages in obtai-ning morphology controlled materials with structural specificity, complexity and their unique functions. The bio-template method combining with electrochemical deposition was employed to synthesize spirulina/hematite composite microstructures using native spirulina as template. A great amount of hematite（a-Fe2O3） nanoparticles can be formed and deposited onto the spirulina, resulting in a robust and pseudo-homogeneous surface. And the spinth- na/a-Fe2O3 composite exhibits an improved surface wettability due to its helical morphology. This facile strategy may open new horizons in the field of replicating specific biological structures for functional materials in other potential applications.
文摘Hematite (α-Fe2O3) nanopowder was synthesized from 0.1 mol·L-1 FeCl3 solution by sonochemical hydrolysis method, and characterized by X-ray diffraction (XRD), transmission electron micrograph (TEM), Fourier transform infrared (FTIR), Fourier transform Raman (FT-Raman) and X-ray photoelectron spectroscopy (XPS). The results showed that the spherical, well-dispersed α-Fe2O3 nanopowder was obtained with the average size of 20 nm. The possible mechanism for the formation of α-Fe2O3 nanoparticals was also discussed.
基金Project supported by the Key Program of the National Natural Science Foundation of China(Grant No.51331003)the International S&T Cooperation Program of China(Grant No.2015DFG52020)+1 种基金the General Program of Science and Technology Development Project of Beijing Municipal Education Commission,China(Grant No.KM201710005006)the State Key Laboratory of Advanced Metals and Materials,China(Grant No.2015-ZD02)
文摘In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S） on the magnetic properties and magnetic reversal modes are systematically analyzed. As S increases from 1 nm to 48 nm, the remanence （Jr） increases, while the coercivity （Hci） decreases, leading to the result that the magnetic energy prod- uct [（BH）max] first increases slowly, and then decreases rapidly, peaking at S = 24 nm with the （BH）max of 72.9 MGOe （1 MGOe = 7.95775 kJ.m-3）. Besides, with the increase of S, the coercivity mechanism of the nanocomposite magnet changes from nucleation to pinning. Furthermore, by observing the magnetic moment evolution in demagnetization pro- cess, the magnetic reversal of the soft phase in the nanocomposite magnet can be divided into three modes with the increase of S： coherent rotation （S 〈 3 nm）, quasi-coherent rotation （3 nm≤S 〈 36 nm）, and the vortex-like rotation （S ≥36 nm）.
文摘We report a facile, two-step hydrothermal synthesis of a novel Co304/a-Fe2O3 branched nanowire heterostructure, which can serve as a good candidate for lithium-ion battery anodes with high Li＋ storage capacity and stability. The single-crystalline, primary C0304 nanowire trunk arrays directly grown on Ti substrates allow for efficient electrical and ionic transport. The secondary a-Fe2O3 branches provide enhanced surface area and high theoretical Li＋ storage capacity, and can also serve as volume spacers between neighboring Co3O4 NW arrays to maintain electrolyte penetration as well as reduce the aggregation during Li＋ intercalation, thus leading to improved electrochemical energy storage performance.
基金This work was supported by the National Natural Science Foundation of China (51972162 and 51703241)the Postdoctoral Foundation of Jiangsu Province (2019Z203 and 2019K001)the Science and Technology Project of Nanchang (2017-SJSYS008)
文摘Fiber-shaped energy storage devices are indispensable parts of wearable and portable electronics.Aqueous rechargeable Ni/Fe battery is a very appropriate energy storage device due to their good safety without organic electrolytes, high ionic conductivity, and low cost. Unfortunately, the low energy density,poor power density and cycling performance hinder its further practical applications. In this study, in order to obtain high performance negative iron-based material, we first synthesized a-iron oxide(α-Fe2O3) nanorods(NRs) with superstructures on the surface of highly conductive carbon nanotube fibers(CNTFs), then electrically conductive polypyrrole(PPy) was coated to enhance the electron, ion diffusion and cycle stability. The as-prepared α-Fe2O3@PPy NRs/CNTF electrode shows a high specific capacity of 0.62 Ah cm-3 at the current density of 1 A cm-3. Furthermore, the Ni/Fe battery that was assembled by the above negative electrode shows a maximum volumetric energy density of 15.47 mWh cm-3 with228.2 mW cm-3 at a current density of 1 A cm-3. The cycling durability and mechanical flexibility of the Ni/Fe battery were tested, which show good prospect for practical application. In summary, these merits make it possible for our Ni/Fe battery to have practical applications in next generation flexible energy storage devices.
基金Item Sponsored by National Natural Science Foundation of China(51174074)Open Fund Project of National Key Laboratory in University of Science and Technology Beijing of China(KF13-02)
文摘CaC12 can be sprayed onto sinter surface, which can improve the low temperature reduction degradation index （RDI＋3.15） of sinter. This has been recognized; however, there are various opinions on the inhibition mechanism of it. At the same time, the corrosion of C1 element on equipment is very serious. First-principle calculations based on density functional theory were performed to investigate the binding mechanisms of calcium species on a a-Fe2 03 （0 0 1） surface. This is crucial in demonstrating the role of the CaC12 on improving the low temperature reduction degrada tion index. It has been determined that C1 could greatly increase the adsorption of the vacuum layer for the Ca/Fe2 03 system and the relaxation produced by adsorption made bond length decrease, bond energies increase and structure compact. Those are the main reasons that inhibiting the reduction disintegration of sinter.
基金supported by the National Basic Research Program of China(2011CB935800)the National Natural Science Foundation of China(21071076,21021062 and 51172106)
文摘High surface energy of high-index facets endows nanocrystals with high activities and thus promotes potential applications such as highly efficient catalysts,special optical,electrical and magnetic devices.But the high surface energy of the high-index facets usually drives them to grow faster than the other facets and finally disappear during the crystal growth,which leads the synthesis of nanocrystals with high-indexed facets exposed to be a great challenge.Herein,we introduced two routes to control the synthesis of-Fe2O3polyhedrons with different sets of high-index facets,one using different metal ions(Ni2+,Cu2+or Zn2+)as structure-directing agents and the other applying polymer surfactant sodium carboxymethyl cellulose(CMC)as additive.The growth process of high-index-Fe2O3polyhedrons was also discussed and possible growth mechanism was proposed.
