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2.
Journal of Solid State Electrochemistry - In order to solve the problem of poor conductivity and expansion of ferric oxide (Fe3O4), firstly, the composite powder of carbon nanotubes (CNTs) and... 相似文献
4.
Journal of Solid State Electrochemistry - Hollow and porous structures grant fantastic physicochemical properties and widespread application in electrochemical energy storage. Here, hollow/porous... 相似文献
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Urchin-like nano/micro-structured Fe3O4/C composite has been successfully synthesized using inexpensive starting materials. The urchin-shaped nano/micro-structure consisted of several oriented nanorods. TEM analysis revealed that there is a large number of pores and uniform amorphous carbon distribution at a nanoscale in the nanorods walls. As used in lithium-ion batteries, the mesoporous Fe3O4/C anode delivered a higher reversible capacity of about 830 mAh g−1 at 0.1 C up to 50 cycles, as well as enhanced high-rate capability compared with urchin-like Fe2O3 and commercial Fe3O4. The improvements can be attributed to the combined effects of the nano/micro-architecture, the porosity, and the ultra-fine carbon matrix, where the three factors would contribute to possess both the merits of nanometer-sized building blocks and micro-sized assemblies and provide high electronic conductivity. It is believed that the results of this study offer new prospects for improving the lithium storage capacity of metal oxides by controlling both architecture and composition. 相似文献
6.
Journal of Solid State Electrochemistry - SnO2/Fe2O3 composites with a novel heterojunction nanostructure are successfully prepared via a facile two-step hydrothermal method. Fe2O3 nanoparticles... 相似文献
7.
Urchin-like nano/micro-structured Fe 3O 4/C composite has been successfully synthesized using inexpensive starting materials. The urchin-shaped nano/micro-structure consisted of several oriented nanorods. TEM analysis revealed that there is a large number of pores and uniform amorphous carbon distribution at a nanoscale in the nanorods walls. As used in lithium-ion batteries, the mesoporous Fe 3O 4/C anode delivered a higher reversible capacity of about 830?mAh?g ?1 at 0.1?C up to 50 cycles, as well as enhanced high-rate capability compared with urchin-like Fe 2O 3 and commercial Fe 3O 4. The improvements can be attributed to the combined effects of the nano/micro-architecture, the porosity, and the ultra-fine carbon matrix, where the three factors would contribute to possess both the merits of nanometer-sized building blocks and micro-sized assemblies and provide high electronic conductivity. It is believed that the results of this study offer new prospects for improving the lithium storage capacity of metal oxides by controlling both architecture and composition. 相似文献
8.
RuO 2/Co 3O 4 thin films with different RuO 2 content were successfully prepared on fluorine-doped tin oxide coated glass plate substrates by spray pyrolysis method, and
their capacitive behavior was investigated. Electrochemical property was performed by cyclic voltammetry, constant current
charge/discharge, and electrochemical impedance spectra. The capacitive performance of RuO 2/Co 3O 4 thin films with different RuO 2 content corresponded to a contribution from a main pseudocapacitance and an additional electric double-layer capacitance.
The specific capacitance of pure Co 3O 4, 15.5%, 35.6%, and 62.3% RuO 2 composites at the current density of 0.2 A g −1 were 394 ± 8, 453 ± 9, 520 ± 10, and 690 ± 14 F g −1, respectively; 62.3% RuO 2 composite presented the highest specific capacitance value at various current densities, whereas 35.6% RuO 2 composite exhibited not only the largest specific capacitance contribution from RuO 2 ( C
sp
RuO2) at the current density of 0.5, 1.0, 1.5, and 2.0 A g −1 but also the highest specific capacitance retention ratio (46.3 ± 2.8%) at the current density ranging from 0.2 to 2.0 A g −1. Electrochemical impedance spectra showed that the contact resistance dropped gradually with the decrease of RuO 2 content, and the charge-transfer resistance ( R
ct) increased gradually with the decrease of RuO 2 content. 相似文献
9.
Ultrasonic spray pyrolysis method was used to prepare Nb-doped TiO 2 porous microspheres with an average diameter of 500 nm for solar photocatalytic applications. The effect of Nb-doping on morphology, structure, surface area, as well as spectral absorption properties of TiO 2 microspheres was investigated with SEM, TEM, XRD, Raman spectra, BET, and UV-Vis absorption spectra. The Nb-doping decreased the grain size of TiO 2 porous microsphere, and influenced its surface area and pore size distribution dependent on the doping concentration, but changed negligibly the morphology and size of TiO 2 microspheres. Moreover, the Nb-doping was observed to extend the spectral absorption of TiO 2 into visible spectrum, and the absorption onset was red-shifted for about 88 nm at a doping level of 5% compared to pristine TiO 2 microspheres. Under solar or visible irradiation, Nb-doped TiO 2 microspheres showed higher photocatalytic activity for methylene blue degradation compared with TiO 2 microspheres, which could be ascribed to the extended light absorption range and the suppression of electron-hole pair recombination. 相似文献
10.
Electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions provides an intriguing pathway to convert N 2 into NH 3. However, significant kinetic barriers of the NRR at low temperatures in desirable aqueous electrolytes remain a grand challenge due to the inert N≡N bond of the N 2 molecule. Herein, we propose a unique strategy for in situ oxygen vacancy construction to address the significant trade-off between N 2 adsorption and NH 3 desorption by building a hollow shell structured Fe 3C/Fe 3O 4 heterojunction coated with carbon frameworks (Fe 3C/Fe 3O 4@C). In the heterostructure, the Fe 3C triggers the oxygen vacancies of the Fe 3O 4 component, which are likely active sites for the NRR. The design could optimize the adsorption strength of the N 2 and N xH y intermediates, thus boosting the catalytic activity for the NRR. This work highlights the significance of the interaction between defect and interface engineering for regulating electrocatalytic properties of heterostructured catalysts for the challenging NRR. It could motivate an in-depth exploration to advance N 2 reduction to ammonia. 相似文献
11.
Fe/FeO/Fe 3O 4 composite was synthesized by a simple solid method using ferric citrate and phenolic resin as raw materials. The reaction processes of raw materials mixture were characterized by thermogravimetric analysis (TGA) under nitrogen. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used to investigate the structure and morphology of the products. The results showed that the obtained material was octahedral Fe/FeO/Fe 3O 4 composite with a size of 2-4 μm. The electrochemical performances of Fe/FeO/Fe 3O 4 composite as anode material were also evaluated, which exhibited a stable specific capacity of 260.3 mAh g -1 and an ideal initial coulombic efficiency of 90.8% in the range of 0.05~3 V at the 5C rate. A good rate capacity of Fe/FeO/Fe 3O 4 composite electrode was also shown by the charge-discharge testing even at the rate of 60C. The better rate capability of Fe/FeO/Fe 3O 4 electrode could be measured in higher temperature. 相似文献
12.
Magnetic poly(divinyl benzene)/Fe(3)O(4) microspheres with a narrow size distribution were produced by entrapping the iron pentacarbonyl precursor within the pores of uniform porous poly(divinyl benzene) microspheres prepared in our laboratory, followed by the decomposition in a sealed cell of the entrapped Fe(CO)(5) particles at 300 °C under an inert atmosphere. Magnetic onionlike fullerene microspheres with a narrow size distribution were produced by annealing the obtained PDVB/Fe(3)O(4) particles at 500, 600, 800, and 1100 °C, respectively, under an inert atmosphere. The formation of carbon graphitic layers at low temperatures such as 500 °C is unique and probably obtained because of the presence of the magnetic iron nanoparticles. The annealing temperature allowed control of the composition, size, size distribution, crystallinity, porosity, and magnetic properties of the produced magnetic microspheres. 相似文献
13.
Two important iron oxides:Fe3O4 and Fe2O3,as well as Fe3O4 and Fe2O3 nanoparticles mingling with Ag were successfully synthesized via a hydrothermal procedure.The samples were confirmed and characterized by X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS).The morphology of the samples was observed by transmission electron microscopy(TEM).The results indicated Fe3O4,Fe2O3,Ag/Fe3O4 and Ag/Fe2O3 samples all were nanoparticles with smaller sizes.The samples were modified on a glassy carbon electrode and their elctrocatalytic properties for p-nitrophenol in a basic solution were investigated.The results revealed all the samples showed enhanced catalytic performances by comparison with a bare glassy carbon electrode.Furthermore,p-nitrophenol could be reduced at a lower peak potential or a higher peak current on a glassy carbon electrode modified with Ag/Fe3O4 or Ag/Fe2O3 composite nanoparticles. 相似文献
14.
Porous Fe(3)O(4)@C nanocapsules with a diameter of about 120 nm (about 50 nm cavity) were synthesized by combining a sacrificial template method with solvothermal treatment. The N(2) adsorption-desorption isotherms reveals their mesoporous structure and large BET surface area (159.8 m(2) g(-1)). The magnetic investigation indicates their superparamagnetic nature and high saturation magnetization (55.93 emu g(-1)). The nanocapsules also exhibit negative zeta potential (-27.59 mV) and possess carboxyl groups on the outer carbon layer, which keeps them highly dispersive in aqueous solution and provides a chelating function for metal ions. The heavy metals removal test demonstrates the excellent affinity of nanocapsules, the high efficiency for different metals (>90%), 79 mg g(-1) adsorption capacity for Pb(2+) and ultrafast removal process (Pb(2+), 99.57% within 1 minute). Protected by a porous carbon layer, the nanocapsules display excellent acidic resistance and adsorption properties even in an acidic solution (pH = 3). Moreover, the metal ions can be easily adsorbed and desorbed through manipulating the pH value for adsorbent regeneration and heavy metal recycling. 相似文献
15.
Journal of Solid State Electrochemistry - LiMn0.8Fe0.2PO4 is a potential candidate cathode material to balance the energy density, safety, and cost of power lithium ion batteries. However, the low... 相似文献
18.
In the presence of Fe 3O 4 nano-particles, a new type of super-paramagnetic Fe 3O 4/Au microspheres with core/shell structures was prepared by reduction of Au 3+ with hydroxylamine. The formation mechanism of the core/shell microspheres was studied in some detail. It was shown that the formation of the complex microspheres can be divided into two periods, that is, surface reaction-controlled process and diffusion-controlled process. The relative time lasted by either process depends upon the amount of Fe 3O 4 added and the initial concentration of Au 3+. XPS analysis revealed that along with increasing in coating amount, the strength of the characteristic peaks of Au increased, and the Auger peaks of Fe weakened and even disappeared. Size distribution analysis showed that the core/shell microspheres are of an average diameter of 180 nm, a little bit larger than those before coating. 相似文献
19.
The porous hierarchical spherical Co 3O 4 assembled by nanosheets have been successfully fabricated. The porosity and the particle size of the product can be controlled by simply altering calcination temperature. SEM, TEM and SAED were performed to confirm that mesoporous Co 3O 4 nanostructures are built-up by numerous nanoparticles with random attachment. The BET specific surface area and pore size of the product calcined at 280 °C are 72.5 m 2 g −1 and 4.6 nm, respectively. Our experiments further demonstrated that electrochemical performances of the synthesized products working as an anode material of lithium-ion battery are strongly dependent on the porosity. 相似文献
20.
The novel three-component Fe 3O 4/TiO 2/Ag composite mircospheres were prepared via a facile chemical deposition route. The Fe 3O 4/TiO 2 mircospheres were first prepared by the solvothermal method, and then Ag nanoparticles were anchored onto the out-layer of TiO 2 by the tyrosine-reduced method. The as-prepared magnetic Fe 3O 4/TiO 2/Ag composite mircospheres were applied as photocatalysis for the photocatalytic degradation of methylene blue. The results indicate that the photocatalytic activity of Fe 3O 4/TiO 2/Ag composite microspheres is superior to that of Fe 3O 4/TiO 2 due to the dual effects of the enhanced light absorption and reduction of photoelectron–hole pair recombination in TiO 2 with the introduction of Ag NPs. Moreover, these magnetic Fe 3O 4/TiO 2/Ag composite microspheres can be completely removed from the dispersion with the help of magnetic separation and reused with little or no loss of catalytic activity. 相似文献
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