共查询到20条相似文献,搜索用时 31 毫秒
1.
Graham A. Bowmaker Paul A. Kilmartin Graham A. Wright 《Journal of Solid State Electrochemistry》1999,3(3):163-171
Stable, yellow anodic films of parathiocyanogen (SCN)
x
were formed on a platinum electrode from 2.8 M KSCN in methanol at 45 °C at a constant current of 20–40 mA cm−2 for 15–30 min. Loosely bound orange crystals of a more amorphous character were removed by rinsing to leave an adherent yellow
film with sharp Raman bands under 647.1 nm laser excitation at 627 cm−1 (vCS), 1152 cm−1 and 1236–1261 cm−1 (vNN and vCN). The lack of electroactivity and short-lived photocurrents pointed to an insulating film at potentials up to 1.0 V (SHE).
At more positive potentials, longer-lasting photocurrents were obtained, consistent with breakdown of the insulating film.
XPS scans confirmed N:C:S ratios close to 1:1:1, with a deficiency of S of some 10% due to S lost as sulfate at the film surface.
Oxidation of SeCN− in neutral aqueous solution led to the formation of a less-stable orange paraselenocyanogen film with a Raman band at 1256–1267 cm−1, which decomposed within a day to grey selenium.
Received: 12 December 1997 / Accepted: 23 March 1998 相似文献
2.
Hongxia Luo Nanqiang Li Weijun He Zujin Shi Zhennan Gu Xihuang Zhou 《Journal of Solid State Electrochemistry》1998,2(6):432-436
Electrochemical behavior of (C70)2-p-tert-butylcalix [8] arene film on a glassy carbon electrode has been studied by cyclic voltammetry. Two pairs of reduction/reoxidation
waves were detected in a mixed solvent of acetonitrile and water containing tetra-n-butylammonium perchlorate as the supporting electrolyte.
Received: 12 January 1998 / Accepted: 22 February 1998 相似文献
3.
Electrochemical and surface analytical study of the formation of oxide films on monel-400 and copper in alkaline media 总被引:1,自引:0,他引:1
S. Rangarajan Santanu Bera S. V. Narasimhan 《Journal of Solid State Electrochemistry》1998,2(2):94-98
The nature of the oxide films formed on monel-400 and copper in presence of NaOH and N-methylpyrrolidine (a volatile amine) at pH 9.5 and in 0.1 M KNO3 medium were investigated. The oxide films were grown by applying an anodic potential of +0.4 V (vs saturated calomel electrode)
for 30 min. The compositions of the surface oxide films were analysed by X-ray photoelectron spectroscopy. In the case of
copper in NaOH medium, Cu(0) and a very small amount of copper hydroxide were observed. However, in amine medium, Cu(0) and
Cu-amine complex were found. For monel in NaOH, the anodic film was found to contain hydroxides of both copper and nickel.
After sputtering, this film showed a small amount of metal oxide below the hydroxide layer as confirmed by the oxygen peak.
In amine medium the anodic film was found to contain only nickel hydroxide and metallic copper. The depth profile analysis
of films showed that the film developed was very thin and the nickel hydroxide was sputtered very easily from the film.
Received: 27 May 1997 / Accepted: 8 September 1997 相似文献
4.
Photoelectrochemical measurements have been performed at a polybithienyl (PBT) film (doping level of 1 × 1018/cm3) deposited on a platinum electrode. The cathodic photocurrents and negative slope of the Mott-Schottky plot indicate that
the PBT film has the features of a p-type semiconductor. The cathodic photocurrents are interpreted in terms of the Gaertner-Butler
model on the basis of the theory of the semiconductor|solution interface. The (i
ph
hν)2/n vs. hν plots taken from the photocurrent spectra show two linearities for n=1 in the wavelength range from 460 nm to 490 nm and for n=4 in the wavelength range λ > 490 nm. The band gaps of the PBT film were determined to be 2.05 ± 0.05 eV for n=1 and 1.55 ± 0.05 eV for n=4. The flat-band potential is 0.33 V (vs SCE). From the slope of the Mott-Schottky plot at the modulation frequency of 3 kHz,
the dielectric constant ɛ of the film and the thickness of the depletion layer W
0 of the PBT film were determined to be 7.4 and 0.29 μm, respectively.
Received: 6 January 1999 / Accepted: 6 June 1999 相似文献
5.
Keunjoo Kim Hong Seub Kim Jae Yon Kim Young Hee Lee Hyung Jae Lee Hwack Joo Lee Hyun Ryu 《Journal of Solid State Electrochemistry》1997,1(3):221-226
The interdiffusion in a low-strained Si0.93Ge0.07/Si epilayer was analyzed by double-crystal X-ray diffraction. The interdiffusion was characterized by a low diffusion barrier
of 1.81 eV with a diffusion constant of 4.3 × 10−5 cm2/sec, which indicates correlation with the stacking fault generated by the homoepitaxial growth of the Si layer prior to the
growth of the strained SiGe layer. At the very low-strained layer, the driving force causing the interdiffusion is the concentration
gradient, and the mechanism is self-diffusion of Si. Furthermore, the interdiffusion mechanisms were classified into three
groups, depending on the Ge mole fraction x. For x < 0.2, the diffusion process in the SiGe alloy is similar to a self-diffusion of Si atoms, while, for 0.2 < x < 0.4, Ge atoms prefer to be diffused out from the alloy. Finally, for x > 0.4, Si atoms can be diffused into the alloy.
Received: 22 April 1997 / Accepted: 4 June 1997 相似文献
6.
J. L. Gautier E. Meza E. Silva C. Lamas C. Silva 《Journal of Solid State Electrochemistry》1997,1(2):126-133
The electrochemical insertion of lithium in the spinel-type manganite with the formula ZnNi
y
Mn2–
y
O4 has been studied. The galvanostatic discharge curves show that the best performance is obtained for y = 0.25, where a tetragonal to cubic structural transformation occurs. The thermodynamics and kinetics of the process of insertion
of the lithium into the tetragonal spinel Li
x
ZnNi0.25Mn1.75O4 (x = 0.05–1.3) have been studied. The molar thermodynamic quantities, such as enthalpy, entropy and free energy determined by
EMF-T measurements, varied with the lithium concentration in the oxide structure, and a major variation was observed around
x = 0.8. The chemical diffusion coefficient of lithium in these spinels was also determined. Structural analysis, degree of
oxidation and magnetic susceptibility measurements were carried out for the lithiated oxides in order to obtain the cationic
distribution as a function of x. It has been possible to demonstrate that, upon lithium insertion, Mn4+ ions on B sites are reduced to Mn3+ and then to Mn2+. A cooperative Jahn-Teller effect is present in these spinel manganese-nickel oxides.
Received: 4 February 1997 / Accepted: 11 April 1997 相似文献
7.
Shangyun Ye Yongyao Xia Pingwei Zhang Zhiyu Qiao 《Journal of Solid State Electrochemistry》2007,11(6):805-810
A series of the mixed transition metal compounds, Li[(Ni1/3Co1/3Mn1/3)1–x-y
Al
x
B
y
]O2-z
F
z
(x = 0, 0.02, y = 0, 0.02, z = 0, 0.02), were synthesized via coprecipitation followed by a high-temperature heat-treatment. XRD patterns revealed that
this material has a typical α-NaFeO2 type layered structure with R3-
m space group. Rietveld refinement explained that cation mixing within the Li(Ni1/3Co1/3Mn1/3)O2 could be absolutely diminished by Al-doping. Al, B and F doped compounds showed both improved physical and electrochemical
properties, high tap-density, and delivered a reversible capacity of 190 mAh/g with excellent capacity retention even when
the electrodes were cycled between 3.0 and 4.7 V. 相似文献
8.
Xian-Liang Zhou Zhi-Guo Ye Xiao-Zhen Hua Ai-Hua Zou Ying-Hu Dong 《Journal of Solid State Electrochemistry》2010,14(7):1213-1219
Ti/IrO2(x) + MnO2(1-x) anodes have been fabricated by thermal decomposition of a mixed H2IrCl6 and Mn(NO3)2 hydrosolvent. Cyclic voltammetry (CV) and polarization curve have been utilized to investigate the electrochemical behavior
and electrocatalytic activity of Ti/IrO2(x) + MnO2(1-x) anodes in 0.5 M NaCl solution (pH = 2). Ti/IrO2+MnO2 anode with 70 mol% IrO2 content has the maximum value of q*, indicating that Ti/IrO2(0.7) + MnO2(0.3) anode has the most excellent electrocatalytic activity for the synchronal evolution of Cl2 and O2 in dilute NaCl solution. Tafel lines displayed two distinct linear regions with one of the slope close to 62 mV dec−1 in the low potential region and the other close to 295 mV dec−1 in the high potential region. Electrochemical impedance spectroscopic is employed to investigate the impedance behavior of
Ti/IrO2(x) + MnO2(1-x) anodes in 0.5 M NaCl solution. It is observed that as the R
ct, R
s and R
f values for Ti/IrO2(0.7) + MnO2(0.3) anode become smaller, electrocatalytic activity of Ti/IrO2(0.7) + MnO2(0.3) anode becomes better than that of other Ti/IrO2 + MnO2 anodes with different compositions. Ti/IrO2(0.7) + MnO2(0.3) anode fabricated at 400 °C has been observed to possess the highest service life of 225 h, whereas the accelerated life
test is carried out under the anodic current of 2 A cm−2 at the temperature of 50 °C in 0.5 M NaCl solution (pH = 2). 相似文献
9.
A novel surfactant peptide consisting of an arginine cation with laurate anion has been synthesized, purified and characterized.
The critical micellar concentration (cmc) of peptide in aqueous solutions has been determined using spectroscopic techniques
and is found to increase from 0.06 to 0.11 mM with increasing temperature (15–45 °C). Cmc is also determined in the presence
of salts like NaCl, KCl and sodium acetate and it is found that these electrolytes hinder aggregation with a significant increase
in the case of sodium acetate. The aggregation number of the surfactant peptide has been determined using fluorescence quenching
measurements and is observed to decrease from 14 to 6 with increasing temperature (15–45 °C). The standard free energy change
(ΔG
0
m) and standard enthalpy change (ΔH
0
m) of the peptide aggregate are found to be negative with a small positive value for standard entropy change (ΔS
0
m). The peptide aggregate seems to undergo phase transition above 50 °C as observed from UV–vis and fluorescence spectroscopy.
From pyrene binding studies, it is shown that the interior dielectric constant increases from 5.08 at 34 °C to 8.77 at 50 °C
and further decreases with increase in temperature indicating a phase change at 50 °C. Also, the ratio of excimer intensity
to monomer intensity, which is a measure of microviscosity of the aggregate, decreases with increase in temperature with a
change at 50 °C indicating a phase change.
Received: 14 February 1997 Accepted: 13 August 1997 相似文献
10.
Using the newly developed multi-reference coupled pair approximation program code, the adiabatic potential curves of the
ground states of F
2, As
2 and As
2
+ were calculated. Computed spectroscopic constants of these molecules were found to be in good agreement with experimental
values. The resulting binding energy of As
2 (3.86 eV) was compared with the experimental value of 3.99 eV [15] and the best multi-reference configuration interaction
value (3.58 eV) reported previously by the present authors. The calculated first adiabatic ionization potential of As
2 (9.67 eV) was found to be in good agreement with the experimental result.
Received: 5 July 1997 / Accepted: 27 August 1997 相似文献
11.
J. Pablo Tomba Daniel Portinha Walter F. Schroeder Mitchell A. Winnik Willie Lau 《Colloid and polymer science》2009,287(3):367-378
This paper describes experiments that investigate the use of low glass transition temperature (T
g) latex particles consisting of oligomer to promote polymer diffusion in films formed from high molar mass polymer latex.
The chemical composition of both polymers was similar. Fluorescence resonance energy transfer (FRET) was used to follow the
rate of polymer diffusion for samples in which the high molar mass polymer was labeled with appropriate donor and acceptor
dyes. In these latex blends, the presence of the oligomer (with M
n = 24,000 g/mol, M
w/M
n = 2) was so effective at promoting the interdiffusion of the higher molar mass poly(butyl acrylate-co-methyl methacrylate; PBA/MMA = 1:1 by weight) polymer (with M
n = 43,00 g/mol, M
w/M
n = 3) that a significant amount of interdiffusion occurred during film drying. Additional polymer diffusion occurred during
film aging and annealing, and this effect could be described quantitatively in terms of free-volume theory.
This paper is dedicated to Professor Haruma Kawaguchi to honor his many contributions to the field of latex particles and
their applications. 相似文献
12.
Summary. The mechanisms of photoinduced processes occurring in methanolic solutions of trans-[Fe(4-R-benacen)(CH3OH)I] (4-R-benacen
2− : N,N′-ethylene-bis-(4-R-benzoylacetoneiminato) tetradentate open-chain Schiff bases with R = H, Cl, Br, CH3, OCH3, or NO2) were investigated by electronic absorption spectroscopy and EPR spin trapping. The complexes are redox-stable in the dark
both in the solid state and in methanolic solutions. Ultraviolet and/or visible irradiation in methanol induces photoreduction
of Fe(III) to Fe(II). No formation of I˙ or was observed. ˙CH2OH radicals and/or solvated electrons were identified in irradiated systems using nitrosodurene or 5,5-dimethyl-1-pyrroline-N-oxide
as spin traps. The final product of the photooxidation coupled with the photoreduction of Fe(III) is formaldehyde, the molar
ratio of Fe(II) and CH2O being close to 2:1. The efficiency of the photoredox process is strongly wavelength dependent and influenced by the peripheral
groups R of the tetradentate ligands. It is suggested that the primary photoredox step starts from thermally nonequilibrated ligand-to-metal
charge transfer excited states.
Received May 2, 2001. Accepted May 30, 2001 相似文献
13.
The electropolymerisation of N-benzylaniline (NBA) at transparent ITO glass electrodes was investigated with in situ UV-visible spectroelectrochemistry.
An intermediate was found to be generated during electrolysis as the precursor of poly(N-benzylaniline) (PNBA). The intermediate, which shows an absorbance band at λ = 460 nm, is able to react spontaneously with
NBA, forming a polymeric end product, which is deposited on the electrode surface. UV-Vis spectra were obtained with PNBA-modified
electrodes at various electrode potentials. It was shown that the colouration of the PNBA film after a positive-going potential
step proceeds ca. 5 times slower than its discolouration after the reverse negative-going potential step. Anodic degradation
of PNBA film was shown to proceed when holding the electrode at a sufficiently high positive potential. A linear dependence
between the first-order degradation rate constant (k/s−1) and electrode potential (E/V) was found in the potential range of E
RHE = +0.8 to +1.1 V: log k = a + bE, where a = −8.75 and b = 5.45 are empirical coefficients. In the whole spectral range investigated, the degradation of PNBA was found to proceed
faster as compared to that of polyaniline (for polyaniline, coefficients a = −12.7 and b = 8.96 were obtained in the potential range of E
RHE = +0.85 to +1.1 V). The electrooxidation of hydroquinone, as well as the electroreduction of benzoquinone, were shown to
proceed at PNBA-modified electrodes. In these processes, PNBA was shown to play the role of an electron mediator between the
ITO electrode and solution phase redox species.
Received: 8 January 1999 / Accepted: 27 January 1999 相似文献
14.
Yoshihiro Kawakami Hiromasa Ikuta Masataka Wakihara 《Journal of Solid State Electrochemistry》1998,2(4):206-210
Perovskite-type compounds, Li
x
La(1−
x
)/3NbO3 and (Li0.25La0.25)1−
x
Sr0.5
x
NbO3 as lithium ionic conductors, were synthesized by a solid-state reaction. From powder X-ray diffraction, the solid solution
ranges of the two compounds were determined to be 0≤x≤0.25 and 0≤x≤0.125, respectively. In the Li
x
La(1−
x
)/3NbO3 system, the ionic conductivity of lithium at room temperature, σ25, exhibited a maximum value of 4.7 × 10−5 S · cm−1 at x = 0.10. However, because of the decrease in the lattice parameters with increasing Li concentration x˙, σ25 of the samples decreased with increasing x from 0.10 to 0.25. Also, in the (Li0.25La0.25)1−
x
Sr0.5
x
NbO3 system, the lattice parameter increased with the increase of Sr concentration and the σ25 achieved a maximum (7.3 × 10−5 S · cm−1 at 25 °C) at x = 0.125.
Received: 12 September 1997 / Accepted: 15 November 1997 相似文献
15.
The electrochemical behaviour of new doped Li-M-Mn-O (M = Al, Fe, Ni) spinel oxides in liquid electrolyte lithium cells was
studied. The insertion electrode materials were obtained by heating stoichiometric amounts of thoroughly mixed LiOH and M
x
Mn1−
x
CO3 (M = Fe, Ni; x = 0.08−0.15) or Al
x
Mn1−
x
(CO3) (OH)
y
, in the case of Al, at 380 °C in air for 20 h. The transition metal-doped samples, particularly those containing Ni or obtained
at low temperatures, where the resulting spinel was cation-deficient and highly disordered, exhibited the best cycling performance
in the potential window 3.3−2.3 V. Cell capacity was retained by 80% after 200 cycles. Capacity fading was observed on increasing
the firing temperature, together with improved crystallinity and the disappearance of cation vacancies. This impaired electrochemical
behaviour is ascribed to a Jahn-Teller effect, which induces an X-ray-detectable cubic-tetragonal phase transition upon lithium
insertion. The phase transition was undetectable in the low-temperature samples. The influence of the Jahn-Teller distortion
is thus seemingly lessened by a highly disordered structure.
Received: 25 November 1997 / Accepted: 28 January 1998 相似文献
16.
Mohammad Ali Kamyabi Z. Asgari H. Hosseini Monfared 《Journal of Solid State Electrochemistry》2010,14(9):1547-1553
A carbon past electrode modified with [Mn(H2O)(N3)(NO3)(pyterpy)],
( \textpyterpy = 4¢- ( 4 - \textpyridyl ) - 2,2¢:\text6¢,\text2¢¢- \textterpyridine ) \left( {{\text{pyterpy}} = 4\prime - \left( {4 - {\text{pyridyl}}} \right) - 2,2\prime:{\text{6}}\prime,{\text{2}}\prime\prime - {\text{terpyridine}}} \right) complex have been applied to the electrocatalytic oxidation of nitrite which reduced the overpotential by about 120 mV with
obviously increasing the current response. Relative standard deviations for nitrite determination was less than 2.0%, and
nitrite can be determined in the ranges of 5.00 × 10−6 to 1.55 × 10−2 mol L−1, with a detection limit of 8 × 10−7 mol L−1. The treatment of the voltammetric data showed that it is a pure diffusion-controlled reaction, which involves one electron
in the rate-determining step. The rate constant k′, transfer coefficient α for the catalytic reaction, and diffusion coefficient of nitrite in the solution, D, were found to be 1.4 × 10−2, 0.56× 10−6, and 7.99 × 10−6 cm2 s−1, respectively. The mechanism for the interaction of nitrite with the Mn(II) complex modified carbon past electrode is proposed.
This work provides a simple and easy approach to detection of nitrite ion. The modified electrode indicated reproducible behavior,
anti-fouling properties, and stability during electrochemical experiments, making it particularly suitable for the analytical
purposes. 相似文献
17.
Dominique Larcher Bernard Gérand Jean-Marie Tarascon 《Journal of Solid State Electrochemistry》1998,2(3):137-145
The spinel phases Li1+
y
Mn2−
y
O4 have been synthesized by a novel synthesis method that presents advantages compared to the classical ceramic method, namely,
in terms of preparation time, costs and electrochemical performances of the resulting products. This consists of a two-stage
process. First, two precursor phases (Li-EG and Mn-EG) are synthesized by reacting powdered lithium hydroxide and electrolytic
manganese dioxide (EMD) in ethylene glycol (EG) under reflux, respectively. Secondly, the precursor products are mixed and
heat treated under air, following various heating sequences, to produce electrochemically active Li1+
y
Mn2−
y
O4 powders of well-defined morphology. Once the synthesis parameters involved in these two steps are controlled, the obtained
Li1+
y
Mn2-
y
O4 powders exhibit electrochemical performances that compare favorably with those observed in the case of the high-temperature
(HT) Li1+
y
Mn2−
y
O4 made by the ceramic route, both in terms of reversible/irreversible capacities and cycling behavior at 25 °C and 55 °C.
Received: 12 August 1997 / Accepted: 20 October 1997 相似文献
18.
Hydrophobic layered double hydroxides (LDHs): Selective adsorbents for liquid mixtures 总被引:1,自引:0,他引:1
The external and internal surface area of the calcium aluminum double hydroxide [Ca2Al(OH)6] NO3 ⋅ 2H2O were hydrophobized by the anionic surfactants sodium dodecylsulfate and sodium dodecyl-benzene sulfonate. The adsorption
behavior towards liquid mixtures (benzene/n-heptane and n-propanol/ toluene) was studied by determining the surface excess adsorption isotherms, the heats of immersion in these liquids,
and the basal spacing, i.e. the expansion of the interlayer space.
Both hydrophobic layered double hydroxides (LDHs) adsorbed n-hep-tane, benzene, toluene, and n-pro-panol between the layers with considerable increase of the basal spacing. Interlamellar swelling of the hydrophobizised
LDHs in n-heptane was fundamentally different to the behavior of hydrophobized 2 : 1 clay minerals (smectites, vermiculites). The surface
excess isotherms for benzene/ heptane mixtures were U-shaped and indicate preferential adsorption of benzene. Dodecylbenzene
sulfonate double hydroxide preferentially adsorbed propanol from n-propanol/ toluene mixtures but the dodecyl-sulfate derivative adsorbed both compounds.
Received: 23 January 1997 Accepted: 10 February 1997 相似文献
19.
Kumar S. Ashok Wang Sea-Fue Yeh Chun-Ting Lu His-Chuan Yang Jen-Chang Chang Yu-Tsern 《Journal of Solid State Electrochemistry》2010,14(11):2129-2135
In this study, stable and homogenous thin films of multiwalled carbon nanotubes (MWCNTs) were obtained on conducting surface
using ciprofloxacin (CF, fluoroquinolone antibiotic) as an effective-dispersing agent. Further, MWCNTs/CF film modified electrodes
(glassy carbon and indium tin oxide-coated glass electrode) are used successfully to study the direct electrochemistry of
proteins. Here, cytochrome C (Cyt-C) was used as a model protein for investigation. A MWCNTs/CF film modified electrode was
used as a biocompatible material for immobilization of Cyt-C from a neutral buffer solution (pH 7.2) using cyclic voltammetry
(CV). Interestingly, Cyt-C retained its native state on the MWCNTs/CF film. The Cyt-C adsorbed MWCNTs/CF film was characterized
by scanning electron microscopy (SEM), UV–visible spectrophotometry (UV-vis) and CV. SEM images showed the evidence for the
adsorption of Cyt-C on the MWCNTs/CF film, and UV–vis spectrum confirmed that Cyt-C was in its native state on MWCNTs/CF film.
Using CV, it was found that the electrochemical signal of Cyt-C was highly stable in the neutral buffer solution and its redox
peak potential was pH dependent. The formal potential (−0.27 V) and electron transfer rate constant (13 ± 1 s−1) were calculated for Cyt-C on MWCNTs/CF film modified electrode. A potential application of the Cyt-C/MWCNTs/CF electrode
as a biosensor to monitor H2O2 has been investigated. The steady-state current response increases linearly with H2O2 concentration from 2 × 10−6 to 7.8 × 10−5 M. The detection limit for determination of H2O2 has been found to be 1.0 × 10−6 M (S/N = 3). Thus, Cyt-C/MWCNTs/CF film modified electrode can be used as a biosensing material for sensor applications. 相似文献
20.
Aleksey A. Yaremchenko Vladislav V. Kharton Evgeny N. Naumovich Alim A. Vecher 《Journal of Solid State Electrochemistry》1998,2(3):146-149
The minimum concentration of niobium to stabilize the fluorite-type f.c.c. phase in the Bi2O3–Nb2O5 oxide system at temperatures below 996 K was ascertained to be about 10 mol%. Thermal expansion, electrical conductivity
and crystal lattice parameters of the Bi(Nb)O1.5+δ solid solutions decrease with increasing niobium content. Thermal expansion coefficients were calculated from the dilatometric
data to be (10.314.5)×10−6 K−1 at temperatures in the range 300–700 K and (17.526.0)×10−6 K−1 at 700–1100 K. The conductivity of the Bi1−
x
Nb
x
O1.5+δ ceramics is predominantly ionic. The p-type electronic transference numbers of the Bi(Nb)O1.5+δ solid solutions in air were determined to be less than 0.1. Annealing at temperatures below 900 K results in a sharp decrease
in conductivity of the Bi1−
x
Nb
x
O1.5+δ ceramics.
Received: 18 August 1997 / Accepted: 20 October 1997 相似文献