共查询到20条相似文献,搜索用时 89 毫秒
1.
Pyonghun Kim Hongwei Xie Yuchun Zhai Xiangyu Zou Xiaochuan Lang 《Journal of Applied Electrochemistry》2012,42(4):257-262
The electrochemical reduction of Dy2O3 in CaCl2 melt was studied. The cyclic voltammetry, chronoamperometry, AC impedance and constant voltage electrolysis were employed.
A single cathodic current peak in the cyclic voltammogram and one response semicircle in the AC impedance spectrum were observed,
supporting a one-step electrochemical reduction mechanism of Dy2O3. No intermediates were observed by XRD, which confirmed the following electrochemical reduction sequence: Dy2O3 → Dy. The charge transfer resistances and the activation energies involved in the electrochemical reduction step of Dy2O3 were obtained by simulating the AC impedance spectra with equivalent circuits. The electrochemical reduction reaction of
Dy2O3 is controlled by the charge transfer process at a low voltage range and by the diffusion process at a high voltage range. 相似文献
2.
Hong Yan Chu Qiong Yu Lai Yan Jing Hao Yan Zhao Xiao Yun Xu 《Journal of Applied Electrochemistry》2009,39(10):2007-2013
Spinel Li4Mn5O12 was prepared by a sol–gel method. The manganese oxide and activated carbon composite (MnO2-AC) were prepared by a method in which KMnO4 was reduced by activated carbon (AC). The products were characterized by XRD and FTIR. The hybrid supercapacitor was fabricated
with Li4Mn5O12 and MnO2-AC, which were used as materials of the two electrodes. The pseudocapacitance performance of the Li4Mn5O12/MnO2-AC hybrid supercapacitor was studied in various aqueous electrolytes. Electrochemical properties of the Li4Mn5O12/MnO2-AC hybrid supercapacitor were studied by using cyclic voltammetry, electrochemical impedance measurement, and galvanostatic
charge/discharge tests. The results show that the hybrid supercapacitor has electrochemical capacitance performance. The charge/discharge
test showed that the specific capacitance of 51.3 F g−1 was obtained within potential range of 0–1.3 V at a charge/discharge current density of 100 mA g−1 in 1 mol L−1 Li2SO4 solution. The charge/discharge mechanism of Li4Mn5O12 and MnO2-AC was discussed. 相似文献
3.
Co3O4 nanorods have been successfully synthesized by thermal decomposition of the precursor prepared via a facile and efficient
microwave-assisted hydrothermal method, using cetyltrimethylammonium bromide (CTAB) with ordered chain structures as soft
template for the first time. The obtained Co3O4 was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM),
and electrochemical measurements. The results demonstrate that the as-synthesized nanorods are single crystalline with an
average diameter of about 20 to 50 nm and length up to several micrometers. Preliminary electrochemical studies, including
cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS) measurements, are
carried out in 6 M KOH electrolyte. Specific capacitance of 456 F g−1 for a single electrode could be achieved even after 500 cycles, suggesting its potential application in electrochemical capacitors.
This promising method could provide a universal green chemistry approach to synthesize other low-cost and environmentally
friendly transition metal hydroxide or oxide. 相似文献
4.
C. O. Soares M. D. Carvalho M. E. Melo Jorge A. Gomes R. A. Silva C. M. Rangel M. I. da Silva Pereira 《Journal of Applied Electrochemistry》2012,42(5):325-332
LaNiO3 coatings on nickel-foam supports were prepared by brush painting. The electrochemical properties were investigated by cyclic
voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Comparative studies were performed with LaNiO3-pelleted electrodes. The roughness factors were determined by CV and found to be 5,208 ± 350 and 4,037 ± 250 for the pelleted
and coated electrodes, respectively. EIS measurements confirm the results obtained by CV. Values lower than 0.3 were calculated
for the morphology factors for both electrodes, indicating low electrochemical porosity. The experimental method used in this
work to synthesise the oxide coupled with the use of Ni foam as support has proved to be very effective in producing oxide
electrodes with surface areas higher than those referred to in relevant literature. 相似文献
5.
F. M. Sapountzi S. Brosda K. M. Papazisi S. P. Balomenou D. Tsiplakides 《Journal of Applied Electrochemistry》2012,42(9):727-735
The performance of La0.75Sr0.25Cr0.9M0.1O3 (M = Mn, Fe, Co, and Ni) perovskitic materials as anodes was studied for a CO-fueled solid oxide fuel cell. The electrocatalytic performance and the tolerance to carbon deposition were investigated, while electrochemical characterization was carried out via AC impedance spectroscopy and cyclic voltammetry. The La0.75Sr0.25Cr0.9Fe0.1O3 perovskite showed the best anode performance at temperatures above 900 °C; while at temperatures below 900 °C, the best performance was achieved with the La0.75Sr0.25Cr0.9Co0.1O3 material. AC impedance spectroscopy was used for a semi-quantitative analysis of the LSC-M0.1 anodes performance in view of total cell and charge transfer resistance. All anode materials exhibit high electronic conductivity and presumably do not substantially contribute to the overall cell resistance and concomitant ohmic losses. 相似文献
6.
Nanoparticles of lithium cobalt oxide (LiCoO2) were synthesized by means of a citrate sol–gel combustion route. The particles were characterized by scanning and transmission
electron microscopies (SEM and TEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction (XRD) measurements. Near
spherical nanoparticles of around 100 nm were observed in SEM and TEM micrographs. XRD data indicated that the as-prepared
nanoparticles presented pure phase of LiCoO2 with R-3m symmetry. The kinetics of electrochemical intercalation of lithium into the nanoparticles were investigated by means of cyclic
voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) with special emphasis on the application
potential as cathode material for aqueous rechargeable lithium batteries. CV studies of the nanoparticles at slow scan rate
of 0.1 mV s−1 between 600 and 820 mV versus Ag/AgCl, demonstrated that the nanoparticles represented well-defined reversible peaks. The
non-linear chemical diffusion of lithium into the nanoparticles was explored by EIS. In this regards, the results were discussed
based on an equivalent circuit, distinguishing the kinetic properties of lithium intercalation. The kinetic parameters of
lithium intercalation were obtained using the equivalent circuit, which were in good agreement with the experimental results.
The changes of kinetic parameters of lithium intercalation with potential were also discussed in detail. 相似文献
7.
Shengyao Chen Changhuan Mi Linghao Su Bo Gao Qingbin Fu Xiaogang Zhang 《Journal of Applied Electrochemistry》2009,39(10):1943-1948
LiMn2O4/multi-walled carbon nanotubes (MWNTs) composite was synthesized by mechanical activation reaction followed by a heat-treatment
(500 °C). The LiMn2O4 and LiMn2O4/MWNTs as cathodes were investigated in 1 M Li2SO4 by cyclic voltammetry (CV), galvanostatic charge/discharge (GC), and electrochemical impedance spectroscopy (EIS). The LiMn2O4/MWNTs cathode delivered higher discharge capacity (117 mAh g−1) than LiMn2O4 (84.6 mAh g−1). Furthermore, the results from EIS showed that LiMn2O4/MWNTs had a faster kinetic process for lithium ion intercalation/de-intercalation than LiMn2O4. Besides, LiMn2O4/MWNTs had better cycling stability and rate capability than LiMn2O4, which was confirmed by GC testing. SEM images showed that a three-dimensional network structure was formed during the mechanical
activation, giving a decrease of particle size. 相似文献
8.
Xiaofang Ying Haihui Zhou Jiaqi Hu Yan Xu Jinxiang Zeng Jinhua Chen Yafei Kuang 《Journal of Applied Electrochemistry》2009,39(8):1273-1278
The electrochemical behavior of potassium ferrocyanide [K4Fe(CN)6] at Pt/ionic liquid (IL) microemulsion interfaces was investigated by cyclic voltammetry (CV) and electrochemical impedance
spectroscopy (EIS). H2O/TX-100/bmimPF6 was used to prepare three IL microemulsions: water in 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6) (W/IL), bicontinuous (WIL) and bmimPF6 in water (IL/W). The results show that the IL microemulsion systems have relatively narrower potential windows compared with
the pure IL system. The redox potential gap is about 100 mV in the pure water and the three IL microemulsions. The redox potentials
of K4Fe(CN)6/K3Fe(CN)6 and the redox peak currents decrease in the order pure water, IL/W, WIL, W/IL. Furthermore, the peak currents increase linearly
with the square root of the scan rate, while the diffusion coefficient increased in the order W/IL, WIL, IL/W. The Nyquist
plots obtained in the WIL and IL/W systems show capacitive resistance arcs at high frequencies and 45° straight lines at low
frequencies, implying that the electrochemical reactions are controlled by charge transfer and diffusion steps. For the W/IL
system there is only a 45° straight line in the Nyquist plot, indicating that diffusion is the controlling step at all frequencies. 相似文献
9.
The nanosized Mn3O4 particles were prepared by microwave-assisted reflux synthesis method. The prepared sample was characterized using various techniques such as X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman analysis, and transmission electron microscopy (TEM). Electrochemical properties of Mn3O4 nanoparticles were investigated using cyclic voltammogram (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge analysis in different electrolytes such as 1 M KCl, 1 M Na2SO4, 1 M NaNO3, and 6 M KOH electrolytes. XRD pattern reveals the formation of single-phase Mn3O4 nanoparticles. The FT-IR and Raman analysis also assert the formation of Mn3O4 nanoparticles. The TEM image shows the spherical shape particles with less than 50 nm sizes. Among all the electrolytes, the Mn3O4 nanoparticles possess maximum specific capacitance of 94 F g−1 in 6 M KOH electrolyte calculated from CV. The order of capacitance obtained by various electrolytes is 6 M KOH > 1 M KCl > 1 M NaNO3 > 1 M Na2SO4. The EIS and galvanostatic charge–discharge results further substantiate with the CV results. The cycling stability of Mn3O4 electrode reveals that the prepared Mn3O4 nanoparticles are a suitable electrode material for supercapacitor application. 相似文献
10.
MingYan Wang DongEn Zhang ZhiWei Tong XingYou Xu XuJie Yang 《Journal of Applied Electrochemistry》2011,41(2):189-196
Flowerlike Co3O4 nanoparticles were used as a modifier on the glassy carbon electrode to fabricate a quercetin (Qu) sensor. The morphology
and crystallinity of the prepared Co3O4 material were investigated by scanning electron microscopy and X-ray diffraction. Electrochemical behavior of Qu at the sensor
was studied by cyclic voltammetry and semi-derivative voltammetry. Results suggested that the modified electrode exhibited
a strong electrocatalytic activity toward the redox of Qu. The electron transfer coefficient (α), the number of electron transfer
(n), and the diffusion coefficient (D) of Qu at the sensor were calculated. Under the optimum conditions, the catalytic peak currents of Qu were linearly dependent
on the concentrations of Qu in the range from 5.0 × 10−7 to 3.3 × 10−4 M, with a detection limit of 1.0 × 10−7 M. This proposed method was successfully applied to determine the quercetin concentration in Ginkgo leaf tablet and human
urine samples. 相似文献
11.
A layered LiNi0.8Co0.2O2 solid solution, which is a promising cathode material for secondary lithium batteries, was successfully synthesized by an emulsion drying method. Because electrochemical properties significantly depend on the conditions of the synthesis, the calcination temperature was carefully determined on the basis of X-ray diffraction and TG studies. The prepared cathodes were characterized by means of SEM, BET, X-ray diffraction, Rietveld refinement, cyclic voltammetry and a charge-discharge experiment. From the Rietveld analysis, it was found that powder calcined at 800 °C for 12 h exhibits a well ordered and lower cation mixed layered structure than the others. The cyclic voltammetry experiment shows that phase transformation can be suppressed considerably by increasing the calcination temperature to 800 °C. The highest discharge capacity of 188.4 mA h g−1 was obtained from the sample prepared at 800 °C. Furthermore, a high capacity retention ratio of 88.1% was found for the initial value after 50 cycles at a constant current density of 40 mA g−1 between 2.7 VLi/Li+ and 4.3 VLi/Li+. In the rate capability test, the cathode delivered a higher discharge capacity of 153.1 mA h g−1 at a 4 C (800 mA g−1) rate. 相似文献
12.
M. G. Hosseini R. Ordikhani-Seyedlar V. Daneshvari-Esfahlan 《Journal of Porous Materials》2017,24(5):1155-1163
Palladium nanoparticles/zirconium oxide nanotubes/zirconium (Pd-NPs/ZrO2-NTs/Zr) electrodes were prepared by electroless plating method. ZrO2-NTs consisting of individual nanotubes of about 60–80 nm diameters were fabricated by anodizing Zr foil in electrolyte solution containing dimethylformamide, glycerol, water and ammonium fluoride. The morphology and surface characteristics of ZrO2-NTs and Pd-NPs/ZrO2-NTs/Zr electrodes studied using scanning electron microscopy as well as energy dispersive X-ray spectroscopy. The results revealed that Pd-NPs were homogeneously deposited on the surface of ZrO2-NTs. Moreover, electrocatalytic properties of Pd-NPs/ZrO2-NTs/Zr and flat Pd electrodes toward methanol oxidation were investigated using cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry. The results indicated that Pd-NPs/ZrO2-NTs/Zr electrode represents an enhanced electrocatalytic activity and better stability for methanol oxidation compared to flat Pd. Thus, the Pd-NPs/ZrO2-NTs/Zr catalyst is expected to be a promising electrode material for direct methanol fuel cells. Additionally, the effects of scan rate, methanol concentration and temperature dependency of methanol oxidation on Pd-NPs/ZrO2-NTs/Zr electrode have been explored in this study. 相似文献
13.
Kwiyong Kim Chung-Yul Yoo Jong-Nam Kim Hyung Chul Yoon Jong-In Han 《Korean Journal of Chemical Engineering》2016,33(6):1777-1780
Nano-Fe2O3 and CoFe2O4 were suspended in molten salt of alkali-metal chloride (LiCl-KCl-CsCl) and their catalytic activity in electrochemical ammonia synthesis was evaluated from potentiostatic electrolysis at 600 K. The presence of nanoparticle suspension in the molten chloride resulted in improved production of NH3, recording NH3 synthesis rate of 1.78×10?10 mol s?1 cm?2 and 3.00×10?10 mol s?1 cm?2 with CoFe2O4 and Fe2O3, which are 102% and 240% higher than that without the use of a nanocatalyst, respectively. We speculated that the nanoparticles triggered both the electrochemical reduction of nitrogen and also chemical reaction between nitrogen and hydrogen that was produced from water electro-reduction on cathode. The use of nanocatalysts in the form of suspension offers an effective way to overcome the sluggish nature of nitrogen reduction in the molten chloride electrolyte. 相似文献
14.
Mustafa Aghazadeh Isa Karimzadeh Mohammad Ghannadi Maragheh Mohammad Reza Ganjali 《Korean Journal of Chemical Engineering》2018,35(6):1341-1347
A novel electrochemical procedure was developed for the facile preparation of Gd-doped iron oxide nanoparticles (GdIO-NPs). A simple galvanostatic deposition (i=10 mA cm-2) was done in an additive-free aqueous solution containing FeCl2·4H2O, Fe(NO3)3·9H2O and GdCl3·6H2O. The XRD, FE-SEM, EDS and TEM characterizations showed that the product is composed of 15% GdIO-NPs with 10 nm in size. VSM analysis proved that the GdIO-NPs are superparamagnetic. The cyclic voltammetry and charge-discharge tests showed that the prepared GdIO-NPs are capable to deliver specific capacity as high as 190.1 F g-1 at 0.5A g-1 and capacity retention of 95.1% after 2000 cycling. Based on the results, it was concluded that the developed electrochemical strategy acts as an efficient procedure for the preparation of lanthanide doped MNPs with proper magnetic and supercapacitive characters. 相似文献
15.
A Pd/C electrode modified by H3PMo12O40 was prepared and its catalytic performance for H2O2 electroreduction in acidic medium was investigated by cyclic voltammograms. Pd nanoparticles supported on Vulcan XC-72 carbon
were prepared by chemical reduction of PdCl2 in aqueous solution using NaBH4 as the reducing agent. X-ray diffraction analysis indicated that the particle size of Pd is around 9.7 nm. The modified electrode
was prepared by cyclic voltammograms in H2SO4 solution containing H3PMo12O40. The results showed that H3PMo12O40 can efficiently enhance the electrocatalytic activity for H2O2 electroreduction on Pd/C. The effect of H3PMo12O40 content on the electrocatalytic activity of the catalyst was also investigated by CV. The best results appeared at the concentration
of H3PMo12O40 = 0.5 mmol L−1. 相似文献
16.
One of the most promising anode materials for Li-ion batteries, Li4Ti5O12, has attracted attention because it is a zero-strain Li insertion host having a stable insertion potential. In this study,
we suggest two different synthetic processes to prepare Li4Ti5O12 using anatase TiO2 nanoprecursors. TiO2 powders, which have extraordinarily large surface areas of more than 250 m2 g-1, were initially prepared through the urea-forced hydrolysis/precipitation route below 100°C. For the synthesis of Li4Ti5O12, LiOH and Li2CO3 were added to TiO2 solutions prepared in water and ethanol media, respectively. The powders were subsequently dried and calcined at various
temperatures. The phase and morphological transitions from TiO2 to Li4Ti5O12 were characterized using X-ray powder diffraction and transmission electron microscopy. The electrochemical performance of
nanosized Li4Ti5O12 was evaluated in detail by cyclic voltammetry and galvanostatic cycling. Furthermore, the high-rate performance and long-term
cycle stability of Li4Ti5O12 anodes for use in Li-ion batteries were discussed. 相似文献
17.
Maamar Fedailaine Sabrina Berkani Mohamed Trari 《Korean Journal of Chemical Engineering》2016,33(7):2027-2033
The photo-electrochemical characterization of the hetero-system CoFe2O4/TiO2 was undertaken for the Ni2+ reduction under solar light. The spinel CoFe2O4 was prepared by nitrate route at 940 °C and the optical gap (1.66 eV) was well matched to the sun spectrum. The flat band potential (-0.21 VSCE) is more cathodic than the potential of Ni2+/Ni couple (-0.6 VSCE), thus leading to a feasible nickel photoreduction. TiO2 with a gap of 3.2 eV is used to mediate the electrons transfer. The reaction is achieved in batch configuration and is optimized with respect to Ni2+ concentration (30 ppm); a reduction percentage of 72% is obtained under sunlight, the Ni2+ reduction is strongly enhanced and follows a first order kinetic with a rate constant of 4.6×10-2 min-1 according to the Langmuir-Hinshelwood model. 相似文献
18.
Various vanadium oxide nanostructures are currently drawn interest for the potential applications of Li batteries, super capacitors,
and electrochromic display devices. In this article, the synthesis of V2O5 nanotubes by hydrothermal method using 1-hexadecylamine (HDA) and PEO as a template and surface reactant were reported, respectively.
The structural properties and electrochemical performances of these nanostructures were investigated for the application of
Li batteries. Structure and morphology of the samples were investigated by XRD, FTIR, SEM, and TEM analysis. The battery with
V2O5 nanotubes electrode showed initial specific capacity of 185 mAhg−1, whereas the PEO surfactant V2O5 nanotubes exhibited 142 mAhg−1. It was found that PEO surfactant V2O5 nanotubes material showed less specific capacity at initial stages but better stability was exhibited at higher cycle numbers
when compared to that of V2O5 nanotubes. The cyclic performance of the PEO surfactant material seems to be improved with the role of polymeric component
due to its surface reaction with V2O5 nanotubes during the hydrothermal process. 相似文献
19.
Artur Braun Sophie Duval Peter Ried Jan Embs Fanni Juranyi Thierry Strässle Ulrich Stimming Rolf Hempelmann Peter Holtappels Thomas Graule 《Journal of Applied Electrochemistry》2009,39(4):471-475
The thermally activated proton diffusion in BaZr0.9Y0.1O3−δ was studied with electrochemical impedance spectroscopy (IS) and quasi-elastic neutron scattering (QENS) in the temperature
range 300–900 K. The diffusivities for the bulk material and the grain boundaries as obtained by IS obey an Arrhenius law
with activation energies of 0.46 eV and 1.21 eV, respectively. The activation energies obtained by IS for the bulk are 0.26 eV
above 700 K and 0.46 eV, below 700 K. The total diffusivity as obtained by IS is by one order of magnitude lower than the
microscopic diffusivity as obtained by QENS. The activation energies obtained by QENS are 0.13 eV above 700 K and 0.04 eV,
below 700 K. At about 700 K, the diffusion constants for IS and QENS have a remarkable crossover, suggesting two processes
with different activation energies. 相似文献
20.
Yuan HL Wang YQ Zhou SM Liu LS Chen XL Lou SY Yuan RJ Hao YM Li N 《Nanoscale research letters》2010,5(11):1817-1821
Based on a low-temperature route, monodispersed CoFe2O4 microspheres (MSs) were fabricated through aggregation of primary nanoparticles. The microstructural and magnetic characteristics
of the as-prepared MSs were characterized by X-ray diffraction/photoelectron spectroscopy, scanning/transmitting electron
microscopy, and vibrating sample magnetometer. The results indicate that the diameters of CoFe2O4 MSs with narrow size distribution can be tuned from over 200 to ~330 nm. Magnetic measurements reveal these MSs exhibit superparamagnetic
behavior at room temperature with high saturation magnetization. Furthermore, the mechanism of formation of the monodispersed
CoFe2O4 MSs was discussed on the basis of time-dependent experiments, in which hydrophilic PVP plays a crucial role. 相似文献