共查询到20条相似文献,搜索用时 31 毫秒
1.
Fatih Köleli Derya Röpke Rezzan Aydin Thorsten Röpke 《Journal of Applied Electrochemistry》2011,41(4):405-413
The ac response of polyaniline thin films on platinum electrodes was measured at different dc potentials during the N2-fixation in methanol + LiClO4 electrolyte with 0.03 mol L−1 H2SO4 for the first time. The optimum film thickness was found to be 1.5 μm, N2-pressure 50 bar and an optimum electrolysis potential of −0.12 V (NHE). The diffusion coefficients for N2 into the polymer film was found to be (5 ± 2)×10−9 cm2 s−1. 相似文献
2.
E. Marin A. Lanzutti L. Guzman L. Fedrizzi 《Journal of Coatings Technology and Research》2012,9(3):347-355
In this study, innovative TiO2/Al2O3 mono/multilayers were applied by atomic layer depositions (ALD) on ASTM-AZ-31 magnesium/aluminum alloy to enhance its well-known
scarce corrosion resistance. Four different configurations of ALD layers were tested: single TiO2 layer, single Al2O3 layer, Al2O3/TiO2 bilayer and Al2O3/TiO2/Al2O3/TiO2 multilayer deposited using Al[(CH3)]3 (trimethylaluminum, TMA), and TiCl4 and H2O precursors. All depositions were performed at 120°C to obtain an amorphous-like structure of both oxide layers. The four
coatings were then investigated using different techniques, such as scanning electron microscope (SEM), stylus profilometer,
glow discharge optical emission spectrometry (GDOES) and polarization curves in 0.05-M NaCl solution. The thickness of all
the coatings was around 100 nm. The layers compositions were successfully investigated by the GDOES technique, although obtained
data seem to be affected by substrate roughness and differences in sputtering rates between ceramic oxides and metallic magnesium
alloy. Corrosion resistance showed to be strongly enhanced by the nanometric coatings, giving lower corrosion current densities
in 0.05-M NaCl media with respect to the uncoated substrate (from 10−4 to 10−6 A/cm2 for the single layers and from 10−4 to 10−8 A/cm2 for the bi- and multilayers). All polarization curves on coated samples also showed a passive region, wider for the bi-layer
(from −0.58 to −0.43 V with respect to Ag/AgCl) and multilayer (from −0.53 to −0.38 V with respect to Ag/AgCl) structures. 相似文献
3.
Flavio H. Oliveira Marly E. Osugi Fabiana M. M. Paschoal Demetrius Profeti Paulo Olivi Maria Valnice Boldrin Zanoni 《Journal of Applied Electrochemistry》2007,37(5):583-592
The generation of active chlorine on Ti/Sn(1−x)Ir
x
O2 anodes, with different compositions of Ir (x = 0.01, 0.05, 0.10 and 0.30 ), was investigated by controlled current density electrolysis. Using a low concentration of
chloride ions (0.05 mol L−1) and a low current density (5 mA cm−2) it was possible to produce up to 60 mg L−1 of active chlorine on a Ti/Sn0.99Ir0.01O2 anode. The feasibility of the discoloration of a textile acid azo dye, acid red 29 dye (C.I. 16570), was also investigated
with in situ electrogenerated active chlorine on Ti/Sn(1−x)Ir
x
O2 anodes. The best conditions for 100% discoloration and maximum degradation (70% TOC reduction) were found to be: NaCl pH 4,
25 mA cm−2 and 6 h of electrolysis. It is suggested that active chlorine generation and/or powerful oxidants such as chlorine radicals
and hydroxyl radicals are responsible for promoting faster dye degradation. Rate constants calculated from color decay versus
time reveal a zero order reaction at dye concentrations up to 1.0 × 10−4 mol L−1. Effects of other electrolytes, dye concentration and applied density currents also have been investigated and are discussed. 相似文献
4.
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
5.
A carbon nanotube/Nafion composite film modified electrode is described for the sensitive and convenient determination of
Pb2+. In the presence of 1% Nafion, multi-walled carbon nanotubes (MWNT) were successfully dispersed into ethanol by ultrasonication.
After evaporating the ethanol, a MWNT/Nafion composite film-modified electrode was achieved. The resulting MWNT/Nafion film
modified electrode possesses high cation exchange capacity, large surface area, strong adsorption ability and catalytic activity.
Compared with the unmodified electrode and Nafion film-modified electrode, the MWNT/Nafion film-modified electrode remarkably
increases the stripping peak current of Pb2+. Furthermore, the influences of supporting electrolyte, volume of MWNT/Nafion suspension, accumulation potential and accumulation
time were investigated. The striping peak current of Pb2+ is proportional to its concentration over the range 8.0 × 10−8 to 6.0 × 10−6 mol L−1. The limit of detection (S/N = 3) is as low as 5.0 × 10−9 mol L−1. Finally, this newly developed method was used to determine Pb2+ in water samples. 相似文献
6.
Titanium (IV) Phosphate copper hexacyanoferrate composite (TiPhCuHCF) was prepared using a new methodology for the synthesis.
A preliminary characterization of the precursor and resulting materials was defined using spectroscopic and chemical techniques.
The cyclic voltammogram of the modified electrode containing TiPhCuHCF exhibited two redox couples. The first and second redox
couples present a formal potential (E
θ′) of 0.18 and 0.76 V and were ascribed to the Cu+/Cu2+ (E
θ′)1 and Fe2+(CN)6/Fe3+(CN)6 (E
θ′)2 processes, respectively. In a preliminary study, the peak located at 0.76 V displays a sensitive response to N-acetylcysteine. The modified graphite paste electrode showed a linear range from 1.0 × 10−5 to 7.0 × 10−4 mol L−1 for the determination of N-acetylcysteine with a limit detection of 6.96 × 10−5 mol L−1 and relative standard deviation of ± 5% (n = 3) and amperometric sensitivity of 24.79 × 10−3 A mol L−1. The modified electrode was electrochemically stable and showed good reproducibility. 相似文献
7.
Ahmad Nozad Golikand Mehdi Asgari Mohammad Ghannadi Maragheh Elaheh Lohrasbi 《Journal of Applied Electrochemistry》2009,39(1):65-70
A multi-wall carbon nanotube (MWNT) modified glassy carbon electrode (GCE) is described for the measurement of trace levels
of uranium by anodic stripping voltammetry. In a pH 4.4 NaAc-Hac buffer containing 0.010 mol L−1 Mg(NO3)2, UO2
2+ was adsorbed onto the surface of a MWNT film coated glassy carbon electrode and then reduced at −0.40 V vs. Ag/AgCl. During
the positive potential sweep the reduced uranium was oxidized and a well-defined stripping peak appeared at +0.20 V vs. Ag/AgCl.
Low concentrations of Mg2+ significantly enhanced the stripping peak currents since they induced UO2
2+ to adsorb at the electrode surface. The response was linear up to 1.2 × 10−7 mol L−1 and the relative standard deviation at 2.0 × 10−8 mol L−1 uranium was 5.2%. Potential interferences were examined. The attractive behavior of the new “mercury-free” uranium sensor
holds promise for on-site environmental and industrial monitoring of uranium. 相似文献
8.
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
9.
Feng Wu Huaquan Lu Yuefeng Su Ning Li Liying Bao Shi Chen 《Journal of Applied Electrochemistry》2010,40(4):783-789
The Li-rich layered cathode material, Li[Ni0.2Li0.2Mn0.6]O2, was synthesized via a “mixed oxalate” method, and its structural and electrochemical properties were compared with the same
material synthesized by the sol–gel method. X-ray diffraction (XRD) shows that the synthesized powders have a layered O3–LiCoO2-type structure with the R-3m symmetry. X-ray photoelectron spectroscopy (XPS) indicates that in the above material, Ni and Mn exist in the oxidation states
of +2 and +4, respectively. The layered material exhibits an excellent electrochemical performance. Its discharge capacity
increases gradually from the initial value of 228 mA hg−1 to a stable capacity of over 260 mA hg−1 after the 10th cycle. It delivers a larger capacity of 258 mA hg−1 at the 30th cycle. The dQ/dV curves suggest that the increasing capacity results from the redox-reaction of Mn4+/Mn3+. 相似文献
10.
N. Papastefanakis D. Mantzavinos A. Katsaounis 《Journal of Applied Electrochemistry》2010,40(4):729-737
The electrochemical oxidation of olive mill wastewater (OMW) over a Ti/RuO2 anode was studied by means of cyclic voltammetry and bulk electrolysis and compared with previous results over a Ti/IrO2 anode. Experiments were conducted at 300–1,220 mg L−1 initial chemical oxygen demand (COD) concentrations, 0.05–1.35 V versus SHE and 1.39–1.48 V versus SHE potential windows,
15–50 mA cm−2 current densities, 0–20 mM NaCl, Na2SO4, or FeCl3 concentrations, 80 °C temperature, and acidic conditions. Partial and total oxidation reactions occur with the overall rate
being near first-order kinetics with respect to COD. Oxidation at 28 Ah L−1 and 50 mA cm−2 leads to quite high color and phenols removal (86 and 84%, respectively), elimination of ecotoxicity, and a satisfactory
COD and total organic carbon reduction (52 and 38%, respectively). Similar performance can be achieved at the same charge
(28 Ah L−1) using lower current densities (15 mA cm−2) but in the presence of various salts. For example, COD removal is less than 7% at 28 Ah L−1 in a salt-free sample, while addition of 20 mM NaCl results in 54% COD reduction. Decolorization of OMW using Ti/RuO2 anode seems to be independent of the presence of salts in contrast with Ti/IrO2 where addition of NaCl has a beneficial effect on decolorization. 相似文献
11.
B. Bellal B. Hadjarab N. Benreguia Y. Bessekhouad M. Trari 《Journal of Applied Electrochemistry》2011,41(7):867-872
High quality crednerite CuMnO2 was prepared by solid state reaction at 950 °C under argon flow. The oxide crystallizes in a monoclinically distorted delafossite
structure associated to the static Jahn–Teller (J–T) effect of Mn3+ ion. Thermal analysis showed that it converts reversibly to spinel Cu
x
Mn3−x
O4 at ~420 °C in air and further heating reform the crednerite above 940 °C. CuMnO2 is p-type, narrow semiconductor band gap with a direct optical gap of 1.31 eV. It exhibits a long-term chemical stability in basic
medium (KOH 0.5 M), the semi logarithmic plot gave an exchange current density of 0.2 μA cm−2 and a corrosion potential of ~−0.1 VSCE. The electrochemical oxygen insertion/desinsertion is evidenced from the intensity–potential characteristics. The flat band
potential (V
fb = −0.26 VSCE) and the holes density (N
A
= 5.12 × 1018 cm−3) were determined, respectively, by extrapolating the curve C
−2
versus the potential to the intersection with C
−2
= 0 and from the slope of the Mott–Schottky plot. From photoelectrochemical measurements, the valence band formed from Cu-3d wave function is positioned at 5.24 ± 0.02 eV below vacuum. The Nyquist representation shows straight line in the high frequency
range with an angle of 65° ascribed to Warburg impedance originating from oxygen intercalation and compatible with a system
under mass transfer control. The electrochemical junction is modeled by an equivalent electrical circuit thanks to the Randles
model. 相似文献
12.
F. Lian P. Axmann C. Stinner Q. G. Liu M. Wohlfahrt-Mehrens 《Journal of Applied Electrochemistry》2008,38(5):613-617
Positive electrode material LiNi1/2Mn1/2O2 was synthesized via the carbonate co-precipitation method and the hydroxide precipitation route to study the effects of the
precursor on its structural and electrochemical properties. The results of X-ray diffraction and Rietveld refinement show
that the carbonate precursor of Ni2+ and Mn2+ exhibits one phase at a pH of 8.5, while the hydroxide deposit separates into Ni(OH)2 and Mn(OH)2 phases under the same experimental conditions. LiNi1/2Mn1/2O2 material prepared from the hydroxide precursor shows 8.9% Li/Ni exchange and a large capacity loss of 11.3% in the first
10 cycles. By contrast, more uniform distribution of transition metal ions and stable Mn2+ in the carbonate precursor contribute to only 7.8% Li/Ni disorder in the obtained LiNi1/2Mn1/2O2, which delivers a reversible capacity of about 182 mAh g−1 at a current rate of 14 mA g−1 between 2.5 and 4.8 V. 相似文献
13.
E. I. Papaioannou S. Souentie F. M. Sapountzi A. Hammad D. Labou S. Brosda C. G. Vayenas 《Journal of Applied Electrochemistry》2010,40(10):1859-1865
The electrochemical promotion of Pt/YSZ and Pt/TiO2/YSZ catalyst-electrodes has been investigated for the model reaction of C2H4 oxidation in an atmospheric pressure single chamber reactor, under oxygen excess between 280 and 375 °C. It has been found
that the presence of a dispersed TiO2 thin layer between the catalyst electrode and the solid electrolyte (YSZ), results in a significant increase of the magnitude
of the electrochemical promotion of catalysis (EPOC) effect. The rate enhancement ratio upon current application and the faradaic
efficiency values, were found to be a factor of 2.5 and 4 respectively, higher than those in absence of TiO2. This significantly enhanced EPOC effect via the addition of TiO2 suggests that the presence of the porous TiO2 layer enhances the transport of promoting O2− species onto the Pt catalyst surface. This enhancement may be partly due to morphological factors, such as increased Pt dispersion
and three-phase-boundary length in presence of the TiO2 porous layer, but appears to be mainly caused by the mixed ionic-electronic conductivity of the TiO2 layer which results to enhanced O2− transport to the Pt surface via a self-driven electrochemical promotion O2− transport mechanism. 相似文献
14.
Hirohito Ueno Junichi Nemoto Keita Ohnuki Mizuki Horikawa Mikio Hoshino Masao Kaneko 《Journal of Applied Electrochemistry》2009,39(10):1897-1905
Photoelectrochemical decomposition of bio-related compounds such as ammonia, formic acid, urea, alcohol, and glycine by a
biophotochemical cell (BPCC) comprising a nanoporous TiO2 film photoanode and an O2-reducing cathode generating simultaneously electrical power was investigated. The bio-related compounds studied were all
photodecomposed by the present BPCC when they were either liquid or soluble in water. It was shown that ethanol exhibits similar
characteristics both under 1 atm O2 and air as studied by cyclic voltammograms. Although the present BPCC utilizes only UV light, a solar simulator at AM 1.5G
and 100 mW cm−2 light intensity gave also moderate photocurrent–photovoltage (J–V) characteristics with about 2/5 of the short circuit photocurrent
(J
sc) values (J
sc) of that under a Xe lamp irradiation at the intensity of 503 mW cm−2. It was demonstrated that varieties of bio-related compounds can be used as a direct fuel simultaneously for photodecomposition
and electrical power generation. The charge transport processes in the BPCC operation were analyzed using glycine by an alternating
current impedance spectroscopy, showing that the charge transfer reactions on the photoanode and the cathode surfaces compose
the major resistance for the cell performance. 相似文献
15.
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
16.
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
17.
Liangyu Gong Xiaohong Liu Linghao Su 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(4):866-870
Nickel hydroxide nanosheets were successfully synthesized by facile solvothermal method without any template. The structure
and morphology of the as-prepared sample were characterized by X-ray diffraction, Fourier transform infrared spectroscopy
and transmission electron microscopy. The observations revealed the formation of hexagonal phase β-Ni(OH)2 nanosheets with an average diameter of about 100–120 nm. Electrochemical studies were carried out using cyclic voltammetry
and galvanostatic charge–discharge tests, respectively. A maximum specific capacitance of 2,342 F g−1, which is the highest reported for a β-Ni(OH)2 electrode, could be achieved in 6 mol L−1 KOH electrolyte within the potential range of 0–0.50 V (vs. SCE) for the obtained β-Ni(OH)2 electrode at 0.4 A g−1, suggesting its potential application in the electrode material for electrochemical capacitors. 相似文献
18.
Jea Hyeok Ryu Bo Gun Park Seuk Buom Kim Yong Joon Park 《Journal of Applied Electrochemistry》2009,39(7):1059-1066
The effect of surface area on the electrochemical properties and thermal stability of Li[Ni0.2Li0.2Mn0.6]O2 powders was characterized using a charge/discharge cycler and DSC (Differential Scanning Calorimeter). The surface area of
the samples was successfully controlled from ~4.0 to ~11.7 m2 g−1 by changing the molar ratio of the nitrate/acetate sources and adding an organic solvent such as acetic acid or glucose.
The discharge capacity and rate capability was almost linearly increased with increase in surface area of the sample powder.
A sample with a large surface area of 9.6–11.7 m2 g−1 delivered a high discharge capacity of ~250 mAh g−1 at a 0.2 C rate and maintained 62–63% of its capacity at a 6 C rate versus a 0.2 C rate. According to the DSC analysis, heat
generation by thermal reaction between the charged electrode and electrolyte was not critically dependent on the surface area.
Instead, it was closely related to the type of organic solvent employed in the fabrication process of the powder. 相似文献
19.
A detailed analysis of potential versus time measurements at galvanostatic charge/discharge conditions (external current change
from −1 to +1 mA cm−2) for two La–Ni alloys in Ar-saturated 0.1 M KOH solution is presented. It is shown that passivation of the electrodes does
not affect the potential jump as a result of current switching over. The value of potential jump allows to calculate the exchange
current density for H2O/H2 system on the tested material. Anodic potential of the hydrogenated electrode (at i
a = const) linearly increases with logarithm of time which allows to evaluate precisely time necessary for oxidation of hydrogen
absorbed during cathodic charging. The method described enables to determine effectiveness of hydrogen absorption by materials
applied for negative electrodes of NiMH batteries. 相似文献
20.
The Sb2O3 doping lead-free glass in Bi2O3-B2O3-BaO ternary system were prepared in the composition of several different subsystem, and the glass powder was produced through
the process of water quenching. Glass transition temperatures (T
g
), glass soften temperatures(T
s
), the volume resistivity (ρ) in the temperature range of 80–200°C, and linear thermal coefficients of expansion in the temperatures
range of 25–300°C (α25–300) were measured for subsystems along with the different ratio of Bi2O3, B2O3 and BaO. For these subsystems, T
g
ranged from 458 to 481°C, and T
s
ranged from 490 to 512°C, both decreasing with the increasing of Bi2O3/B2O3 ratio, and increasing with the increasing of BaO/B2O3 ratio. The measured α25–300 ranged from 65.3 to 76.3 × 10−7 K−1, with values increasing with increasing Bi2O3/B2O3 and BaO/B2O3 ratio. The volume resistivity remains at a high standards, which may caused by it’s non-alkali composition, and it fluctuated
from 1013 to 1011 Ω cm with the temperature varied from 80–200°C. The structure of Bi2O3-B2O3-BaO ternary leadfree glass system was mearsured by FT-IR. The IR studies indicate that these glasses are made up of [BiO6], [BO3], and [BO4] basic structural units, and it appears that Ba2+ acts as a glass-modifier in this ternary system, but the Bi3+ has entered the glass network when it is in relative high content so as to change the α25–300, T
s
and T
g
. 相似文献