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1.
Regular hexagonal Co–Al layered double hydroxides (Co–Al LDH) were synthesized by urea-induced homogeneous precipitation.
This material proved to be nanosheets by scanning electron microscopy and X-ray diffraction measurements. The electrochemical
capacitive behavior of the nanosheets in 1 M KOH solution were evaluated by constant current charge/discharge and cyclic voltammetric
measurements, showing a large specific capacitance of 192 F·g−1 even at the high current density of 2 A·g−1. When multiwall carbon nanotubes (MWNTs) were mixed with the Co–Al LDH, it was found that the specific capacitance and long-life
performance of all composite electrodes at high current density are superior to pure LDH electrode. When the added MWNTs content
is 10 wt%, the specific capacitance increases to 342.4 F·g−1 and remains at a value of 304 F·g−1 until the 400th cycle at 2 A·g−1, showing that this is a promising electrode material for supercapacitors working at heavy load. According to the electrochemical
impedance spectra, MWNTs greatly increase the electronic conductivity between MWNTs and the surface of Co–Al LDH, which consequently
facilitates the access of ions in the electrolyte and electrons to the electrode/electrolyte interface. 相似文献
2.
Mesoporous silica KIT-6 has novel three-dimensional gyroidal channel structure, space group of 1a-3d, and ordered tunable pores up to 10 nm. In this paper, such mesostructured silica was employed as hard template to prepare semicrystalline gyroidal mesoporous MnO2. The structure was investigated by XRD, TEM and HRTEM, and found to be of high quality 1a-3d symmetry, in good accordance with the template structure. The material has a BET surface of 118 m2·g^-1 and pore volume of 0.35 cm3·g^- 1 after eliminating template. Mesoporous MnO2 has shown good electrochemical property as supercapacitor material in 1 mol·L^-1 Na2SO4 and 1 mol·L^-1 LiClO4 solutions, but interesting pseudocapacitance behavior was observed in the case of 6 mol·L^-1 KOH. It was found that mesoporous MnO2 performed stable reversible electrochemical behavior with capacitance of 220 F·g^-1 in a potential range of -0.1-0.55 V vs. Hg/HgO in alkaline solution, demonstrating that it is a promising novel electrode material for the fabrication of electrochemical capacitors. 相似文献
3.
4.
<正>The polymer of complex[Ni(salen)],(N,N'-ethylenebis(salicylideneaminato) nickel(H)),was prepared on graphite electrode by the route of linear sweep potential method.The nano-micro sheaf/wire structures of poly[Ni(salen)]have been obtained by adjusting the polymerization sweep rate of 5,20 and 40 mV·s~(-1).The polymer prepared at 20 mV·s~(-1) had nanoscaled wire structure of ca.100 nm in diameter.The good electrochemical reversibility of poly[Ni(salen)]was investigated by cyclic voltammetry and galvanostatic test in 1.0 mol/L Et_3MeNBF_4/acetonitrile solution.The initial specific gravimetric capacitance of poly[Ni(salen)]at the current density of 0.1 mA·cm~(-2) reached 270.2 F·g~(-1),however,the cycle stability needs to be improved. 相似文献
5.
Polybenzidine (PBz) particles were formed by the chemical polymerization in micelles of block copolymer by using Poly (ethylene oxide)-b-Polystyrene [PEO113-b-PSx (x = 50, 58 and 100)] as templates. The samples were characterized by IR, UV-vis absorption spectroscopy, transmission electron microscopy, cyclic voltammetry, constant current charge-discharge and electrochemical impedance to determine their morphologies and electrochemical properties. The results show that the prepared PBz is submicron to nanometer rod-like conducting particles with uniform sizes. Removing the templates did not affect the morphology but slightly reduced the size of the PBz particles. The size and morphology of PBz particles can be tuned by adjusting the amount of monomer. The PBz submicrorods showed 412 F·g?1 specific capacitance in 0.3 mol·L?1HClO4 at the current density of 1 A·g?1, indicating its better electrochemical activity. The specific capacitance of the PBz particles reduced less than 10% after 500 charge-discharge cycles at the current density of 3 A·g?1, indicating its good cycling stability. 相似文献
6.
石墨烯-氧化钌纳米复合材料的水热法合成及电化学电容性能 总被引:1,自引:0,他引:1
通过水热法制备了石墨烯-氧化钌(G-RuO2)纳米复合材料。对样品进行了X射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM)和能量色散谱(EDS)表征。SEM结果表明氧化钌粒子均匀地分散在石墨烯层片上。TEM结果显示氧化钌纳米粒子的平均粒径约为3 nm。对样品进行了循环伏安和充放电性能测试,结果表明在1 A·g-1的电流密度下,样品在H2SO4(1 mol·L-1)溶液中具有219.7 F·g-1的比电容。 相似文献
7.
Adsorption behavior of rice husk for the decontamination of chromium from industrial effluents 总被引:2,自引:0,他引:2
N. Khalid A. Rahman S. Ahmad A. Toheed J. Ahmed 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(3):775-781
Rice husk, an agricultural waste product, was studied as a potential decontaminant for chromium in the effluents of leather
tanning industries. Physico-chemical parameters such as selection of appropriate electrolyte, shaking time, concentration
of adsorbent and adsorbate were studied to optimize the best conditions in which this material can be utilized on commercial
scale for the decontamination of effluents. The radiotracer technique was used to determine the distribution of chromium.
In certain cases atomic absorption spectrophotometry was also employed. Maximum adsorption was observed at 0.01 mol·dm−3 acid solutions (HNO3, HCl, H2SO4 and HClO4) using 3.0 g of adsorbent for 2.73·10−3 mol·dm−3 chromium concentration in five minutes equilibration time. Studies show that the adsorption decreases with the increase in
the concentrations of all the acids. The adsorption data follows the Freundlich isotherm over the range of 2.73·10−3 to 2.73·10−2 mol·dm−3 chromium concentration. The characteristic Freundlich constants, i.e., 1/n=0.86±0.06 andA=2.35±0.06 mmol·g−1 have been computed for the sorption system. Thermodynamic parameters, i.e., ΔG
0, ΔS
0 and ΔH
0 have also been calculated for the system. Application of the method to a test case of a medium size industry showed that
21 kg of rice husk was sufficient to maintain the NEQS limits of chromium for industrial effluents. 相似文献
8.
Li Chen Changzhou Yuan Bo Gao Shengyao Chen Xiaogang Zhang 《Journal of Solid State Electrochemistry》2009,13(12):1925-1933
An organic–inorganic poly(3,4-ethylenedioxythiophene) (PEDOT)/RuO2·xH2O nanocomposite (approximately 1 wt.% RuO2) has been successfully prepared for the first time under microwave irradiation within 5 min with power 900 W via in situ
chemical polymerization. The morphology and structure of the resultant material is characterized by transmission electron
microscope and Fourier transform infrared. Moreover, the electrochemical properties of the synthesized nanocomposite can be
controlled by adjusting the annealing temperature, which is definitely illustrated by cyclic voltammetry, galvanostatic charge–discharge,
and electrochemical impedance spectra. Electrochemical data have shown that the PEDOT/RuO2·xH2O nanocomposite annealed at 150 °C possesses the most favorable charge/discharge ability with a specific capacitance of 153.3 F
g−1 at a current density of 150 mA g−1 and the high efficient utilization of PEDOT at various current densities. Furthermore, such composite has a less capacitance
degradation of 23.8% after 1,000 continuous cycles. The improved electrochemical performance are mainly attributed to the
large electroactive surface of nanocomposite and the existence of amorphous RuO2·xH2O particles as well as a synergistic effect of the polymer PEDOT and annealed RuO2·xH2O. Thus, the PEDOT/RuO2·xH2O nanocomposite annealed at 150 °C can act as a promising electroactive material for supercapacitor application. 相似文献
9.
Yanhua Li Kelong Huang Dongming Zeng Suqin Liu Zufu Yao 《Journal of Solid State Electrochemistry》2010,14(7):1205-1211
RuO2/Co3O4 thin films with different RuO2 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 RuO2/Co3O4 thin films with different RuO2 content corresponded to a contribution from a main pseudocapacitance and an additional electric double-layer capacitance.
The specific capacitance of pure Co3O4, 15.5%, 35.6%, and 62.3% RuO2 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% RuO2 composite presented the highest specific capacitance value at various current densities, whereas 35.6% RuO2 composite exhibited not only the largest specific capacitance contribution from RuO2 (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 RuO2 content, and the charge-transfer resistance (R
ct) increased gradually with the decrease of RuO2 content. 相似文献
10.
11.
Carbon materials enriched with nitrogen and oxygen surface functional groups were obtained by pyrolyzing strained beer yeast
at 750 °C under an inert atmosphere. Physical and surface properties of the carbon obtained were characterized by X-ray powder
diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, Raman spectrometry, and X-ray
photoelectron spectroscopy. Results show that the carbon possesses an amorphous structure, a spherical morphology, and a high
density of surface functional groups. Electrochemical properties were evaluated by cyclic voltammetry, a galvanostatic charge–discharge
technique, and electrochemical impedance spectroscopy. The carbon has 989.65 mAh·g−1 of initial discharge capacity and a stable cycle performance for a Li–C cell. A specific capacitance of 120 F·g−1 was obtained for a single carbon electrode and good cycle performance was achieved for a symmetrical supercapacitor fabricated
using this carbon. These carbons derived from strained beer yeast have promising applications in energy storage and conversion
systems. 相似文献
12.
Liu Zhiqiang Kang Xueya Li Chengfeng Hua Ning Wumair Tuerdi Han Ying 《Journal of Solid State Electrochemistry》2012,16(5):1917-1923
The electrochemical performance of Li3V2(PO4)3/C was investigated at various low temperatures in the electrolyte 1.0 mol dm−3 LiPF6/ethyl carbonate (EC)+diethyl carbonate (DEC)+dimethyl carbonate (DMC) (volume ratio 1:1:1). The stable specific discharge
capacity is 125.4, 122.6, 119.3, 116.6, 111.4, and 105.7 mAh g−1 at 26, 10, 0, −10, −20, and −30 °C, respectively, in the voltage range of 2.3–4.5 V at 0.2 C rate. When the temperature decreases
from −30 to −40 °C, there is a rapid decline in the capacity from 105.7 to 69.5 mAh g−1, implying that there is a nonlinear relationship between the performance and temperature. With temperature decreasing, R
ct (corresponding to charge transfer resistance) increases rapidly, D (the lithium ion diffusion coefficients) decreases sharply, and the performance of electrolyte degenerates obviously, illustrating
that the low-temperature electrochemical performance of Li3V2(PO4)3/C is mainly limited by R
ct, D
Li, and electrolyte. 相似文献
13.
Changzhou Yuan Long Yang Linrui Hou Diankai Li Laifa Shen Fang Zhang Xiaogang Zhang 《Journal of Solid State Electrochemistry》2012,16(4):1519-1525
A facile hydrothermal strategy was first proposed to synthesize flower-like Co(OH)2 hierarchical microspheres. Further physical characterizations revealed that the flower-like Co(OH)2 microspherical superstructures were self-assembled by one-dimension nanobelts with rich mesopores. Electrochemical performance
of the flower-like Co(OH)2 hierarchical superstructures were investigated by cyclic voltammgoram, galvanostatic charge–discharge and electrochemical
impedance spectroscopy in 3 M KOH aqueous electrolyte. Electrochemical data indicated that the flower-like Co(OH)2 superstructures delivered a specific capacitance of 434 F g−1 at 10 mA cm−2 (about 1.33 A g−1), and even kept it as high as 365 F g−1 at about 5.33 A g−1. Furthermore, the SC degradation of about 8% after 1,500 continuous charge–discharge cycles at 5.33 A g−1 demonstrates their good electrochemical stability at large current densities. 相似文献
14.
Zhang Fang Jiang Jianwei Yuan Changzhou Hao Liang Shen Laifa Zhang Luojiang Zhang Xiaogang 《Journal of Solid State Electrochemistry》2012,16(5):1933-1940
Nanostructured Co
x
Ni1−x
–Al layered triple hydroxides (Co
x
Ni1−x
–Al LTHs) have been successfully synthesized by a facile hydrothermal method using glycine as chelating agent. The samples
were characterized by X-ray diffraction, thermogravimetry, Fourier transform infrared spectroscopy and scanning electron microscopy.
The morphologies of Co
x
Ni1−x
–Al LTHs varied with the Co content and its effect on the electrochemical behavior was studied by cyclic voltammetry and galvanostatic
charge–discharge techniques. Electrochemical data demonstrated that the Co
x
Ni1−x
–Al LTHs with Co/Ni molar ratio of 3:2 owned the best performance and delivered a maximum specific capacitance of 1,375 F g−1 at a current density of 0.5 A g−1 and a good high-rate capability. The capacitance retained 93.3% of the initial value after 1,000 continuous charge–discharge
cycles at a current density of 2 A g−1. 相似文献
15.
The sorption behavior of Sn(II) onto Haro river sand has been examined with respect to nature of electrolyte, agitation time,
dosage of sorbent and concentration of sorbate. Maximum sorption (95.5%) has been achieved from 0.034M hydrochloric acid solution
after equilibrating sorbate (2·10−5M) and sorbent (50 mg) for 120 minutes at aV/W ratio of 90 cm3·g−1. The kinetic data have been subjected to Morris-Weber and Lagergren equations. The kinetics of sorption proceeds a two stage
process consisting of a relatively slow initial uptake followed by a much rapid increase in the sorption. The rate constant
of intraparticle transport, Kd, comes out to be 8.75·10−8 mol·g−1·min−1/2 and the first order rate constant for sorption is 0.0416 min−1. The sorption data of Sn(II) onto Haro river sand followed Langmuir, Freundlich and Dubinin-Radushkevich (D-R) type isotherms.
The Langmuir constant,Q, related to sorption capacity and,b, related to sorption energy are computed to be 10.6±1.1 μmol·g−1 and 1123±137 dm3·mol−1, respectively. The D-R isotherm yields the values ofC
m=348±151 μmol·g−1 and β=−0.01044±0.0008 mol2·kJ−2 and ofE=6.9±0.3 kJ·mol−1. In all three isotherms correlation factor (γ) is ≥0.99. The influence of common anions and cations on the sorption has been
investigated. Zn(II), Mg(II), oxalate, Pb(II), Mn(II) and tartrate reduce the sorption significantly whereas Fe(II) causes
substantial increase in the sorption. It is essential that all ions causing a decrease in the sorption of Sn(II) must be absent
from the sorptive solution otherwise low sorption yields would result. 相似文献
16.
Jing-Jing Deng Jian-Cheng Deng Zi-Ling Liu Hui-Ren Deng Bo Liu 《Journal of Solid State Electrochemistry》2009,13(9):1387-1394
Ni–Co oxide nanocomposite was prepared by thermal decomposition of the precursor obtained via a new method—coordination homogeneous
coprecipitation method. The synthesized sample was characterized physically by X-ray diffraction, scanning electron microcopy,
energy dispersive spectrum, transmission electron microscope, and Brunauer–Emmett–Teller surface area measurement, respectively.
Electrochemical characterization of Ni–Co oxide electrode was examined by cyclic voltammetry, galvanostatic charge–discharge,
and electrochemical impedance measurements in 6-mol L−1 KOH aqueous solution electrolyte. The results indicated that the addition of cobalt oxide not only changed the morphology
of NiO but also enhance its electrochemical capacitance value. A specific capacitance value of 306 F g−1 of Ni–Co oxide nanocomposite with n
Co = 0.5 (n
Co is the mole fraction of Co with respect to the sum of Co and Ni) was measured at the current density of 0.2 A g−1, nearly 1.5 times greater than that of pure NiO electrode. Lower resistance and better rate capability can also be observed. 相似文献
17.
Dou Junqing Kang Xueya Wumaier Tuerdi Hua Ning Han Ying Xu Guoqing 《Journal of Solid State Electrochemistry》2012,16(5):1925-1931
LiFePO4/C composite is synthesized by oxalic acid-assisted rheological phase method. Fe2O3 and LiH2PO4 are chosen as the starting materials, sucrose as carbon sources, and oxalic acid as the additive. The crystalline structure
and morphology of the products are characterized by X-ray diffraction and field emission scanning electron microscopy. The
charge–discharge kinetics of LiFePO4 electrode is investigated using cyclic voltammetry and electrochemical impedance spectroscopy. It is found that the introduction
of appropriate amount of oxalic acid leads to smaller particle sizes, more homogeneous size distribution, and some Fe2P produced in the final products, resulting in reduced polarization, impedance, and improved Li+ ion diffusion coefficient. The best cell performance is delivered by the sample with R = 1.5 (R of the molar ratio of oxalic acid to LiH2PO4). Its discharge capacity is 154 mAh g−1 at 0.2 C rate and 120 mAh g−1 at 5.0 C rate. At the same time, it exhibits an excellent cycling stability; no obvious decrease even after 1,000 cycles
at 1.0 C rate. 相似文献
18.
The composite film of polypyrrole and functionalized multi-walled carbon nanotubes (PPy/F-MWNTs) was prepared by electropolymerization.
MWNTs were functionalized by sonicating with a concentrated solution of H2SO4/HNO3 (3/1, volume ratio) in a water bath for different times. The carbon nanotubes (CNTs) are cut into smaller portions with more
functional groups introduced on their surface when the sonicating time (nominated as functionalization time hereafter) is
increased. However, the specific capacitance of the composite film reaches a maximum of 240 F g−1 at the scanning rate of 10 mV s−1 when MWNTs are functionalized for 24 h, which is about 205 F g−1, 225 F g−1 and 232 F g−1, respectively, when MWNTs are functionalized for 6 h, 12 h and 48 h. At a current load of 1.0 A g−1, PPy/F-MWNT composite film functionalized for 24 h (PPy/F-MWNTs (24 h)) retains 93.49% of its initial capacitance after 1,000
cycles of galvanostatic charge/discharge, and the discharge efficiency is higher than 98.15% during cycling. High specific
capacitance, good rate performance, fast charge/discharge ability and long cycling life are ascribed to the synergistic effect
of the two components to form a porous composite film as well as the easy accessibility of counter ions into the film. Therefore,
PPy/F-MWNT (24 h) composite film is a kind of promising electrode material for supercapacitors. The mechanism of underfunctionalization
and overfunctionalization of carbon nanotubes is also discussed. 相似文献
19.
An amperometric glucose biosensor was developed based on the immobilization of glucose oxidase in the organically modified
silicate (ormosil)-polyvinyl acetate (PVA) matrix onto a Prussian Blue (PB)-modified glassy carbon electrode. A higher stability
PB-modified electrode was prepared by the electrochemical deposition of FeCl3, K3[Fe(CN)6] and ethylenediamine tetraacetic acid (EDTA) under cyclic voltammetric (CV) conditions. The effects of the potential range
of CV conditions, electrolyte cations, applied potential, pH, temperature and co-existing substances were investigated. The
detection limit of the glucose biosensor was 8.1 μmol·L−1 (S/N = 3) with a linear range from 20 μmol·L−1 to 2 mmol·L−1 (R = 0.9965). The biosensor presented a fast response and good selectivity. Additionally, excellent reproducibility and stability
of the biosensor were observed.
Supported by the National High Technical Development Project (863 project) Foundation (Grant No. 2006AA09Z160) and the National
Natural Science Foundation of China (Grant No. 20775064) 相似文献
20.
A new tripodal rhodamine B derivative 2 was designed and synthesized by tripodal trialdehyde and rhodamine B hydrazide for
the first time. This derivative could be used as a fluorescent chemosensor for the selective and sensitive determination of
copper(II) in Tris-HCl buffer and ethanol aqueous mixed media. Under the optimum conditions described herein, fluorescence
enhancement at 557/577 nm was linearly related to the concentration of copper(II) in the range of 0.10 to 10.00×10−5 mol·L−1, with a correlation coefficient of R
2=0.9964 (n=15) and a detection limit of 1.129×10−7 mol·L−1 (the relative standard deviation for five repeated measurements at 4.00×10−5 mol·L−1 Cu(II) was 2.2%). The absorbance measurements at 557 nm were linearly related to the concentration of Cu(II) in the range
of 0.50 to 25.00×10−5 mol·L−1, with a correlation coefficient of R
2=0.9948 (n=13) and a detection limit of 3.338×10−7mol·L−1.
Supported by the Foundation of the Governor of Guizhou Province, China (Grant No. 200617) and the Talented Person Foundation
of Guizhou University (Grant No. 2007039) 相似文献