共查询到20条相似文献,搜索用时 78 毫秒
1.
Shun Koyama Yoshitaka Aoki Shinji Nagata Hiroki Habazaki 《Journal of Solid State Electrochemistry》2011,15(10):2221-2229
Zr–Al alloys containing up to 26 at.% aluminum, prepared by magnetron sputtering, have been anodized in 0.1 mol dm−3 ammonium pentaborate electrolyte, and the structure and dielectric properties of the resultant anodic oxide films have been
examined by grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford backscattering spectroscopy,
and AC impedance spectroscopy. The anodic oxide film formed on zirconium consists of monoclinic and tetragonal ZrO2 with the former being a major phase. Two-layered anodic oxide films, comprising an outer thin amorphous layer and an inner
main layer of crystalline tetragonal ZrO2 phase, are formed on the Zr–Al alloys containing 5 to 16 at.% aluminum. Further increase in the aluminum content to 26 at.%
results in the formation of amorphous oxide layer throughout the thickness. The anodic oxide films become thin with increasing
aluminum content, while the relative permittivity of anodic oxide shows a maximum at the aluminum content of 11 at.%. Due
to major contribution of permittivity enhancement, the maximum capacitance of the anodic oxide films is obtained on the Zr–11 at.%
Al alloy, being 1.7 times than on zirconium at the formation voltage of 100 V. 相似文献
2.
Hidenori Okuzaki Takayoshi Kuwabara Takamitsu Kondo 《Journal of Polymer Science.Polymer Physics》1998,36(14):2635-2642
The sorption-induced bending and recovery motion of PPy films containing different dopant ions have been investigated, and the interaction between water vapor and PPy was studied from sorption isotherms and kinetics. It was found that the PPy/BF4 film exhibited the most rapid motion, and the initial speeds of bending and recovery motion were 7.9 and 5.9 mm s−1, respectively. The linear expansion coefficient of the film increased in order of PPy/DBS, PPy/TsO, PPy/ClO4, and PPy/BF4, which is consistent with the packing density of the PPy chains (ϕPPy). The dual-mode sorption model applied to the isothermal sorption of water vapor to the PPy demonstrated that the Langmuir's capacity constant increased in the same order with the ϕPPy, while the Henry's law constant was nearly constant. The sorption kinetics obeyed Fickian despite the dimensional change of the films, and the PPy/BF4 film had the largest diffusion coefficient of 3.13 × 10−8 cm2 s−1. The experimental results indicated that the kind of dopant ion was crucial to the thermodynamics and kinetics of sorption, and the quick and intensive bending motion of PPy/BF4 films was attributed to the fast diffusion of water vapor, which caused the large dimensional change of the film.© 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2635–2642, 1998 相似文献
3.
In the present investigation, polycrystalline semiconductor Cd–Se–Te films have been electrodeposited at room temperature on conducting glass substrates using cyclic voltammetric technique under controlled periodic scans. The successive anodic and cathodic scans were recorded within the potential range, from 0 to −1.0 V, and over the range of periodic cycles, from 250 to 2,000, in an acidic bath containing respective reducible precursor ions like Cd2+, Se4+, Te4+, and 1 vol.% Triton X-100 as the surface-active reagent. Thin composite films were produced having variable thickness and composition and grain size of the order of 80–100 nm. The film properties were determined by focused ion beam analysis, energy dispersive analysis of x-rays, x-ray diffraction studies, atomic force microscopy, and scanning electron microscopy. Thickness of the semiconductor films was found to increase linearly with the number of voltammetric cycles. Band gap energies of the films as derived from the reflectance spectra were found to lie between 1.4 and 1.7 eV. The composite films of the Cd–Se–Te ternary system when electrochemically characterized in aqueous polysulfide solution exhibited n-type semiconducting properties and photoconversion efficiency more than 0.4%. 相似文献
4.
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
5.
Luis A. Toledo-Matos Maximo Antonio Pech-Canul 《Journal of Solid State Electrochemistry》2011,15(9):1927-1934
The evolution under open-circuit conditions of iron passive films formed at 0.8 VSCE in a borate buffer solution at pH 8.4 was investigated with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry.
The composition of the freshly formed passive film as determined by X-ray photoelectron spectroscopy (XPS) was found to be
in agreement with a bilayer model, where the inner layer is composed mainly of iron oxide and the outer layer consists of
a hydrated material. Results of XPS measurements also showed that the open-circuit breakdown of passive films was consistent
with a reductive dissolution mechanism. When the iron electrode reached an intermediate stage in the open-circuit potential
decay (approximately −0.3 VSCE), the oxide film, containing both Fe(II) and Fe(III), was still protective. The impedance response in this stage exhibited
a mixed control by charge transfer at the metal/film and film/solution interfaces and diffusion of point defects through the
film. At the final stage of the open-circuit potential decay (approximately −0.7 VSCE), the oxide film was very thin, and the ratio of Fe3+/Fe2+ and O2−/OH− had decreased significantly. The impedance response also exhibited a mixed charge-transfer–diffusion control, but the diffusion
process was related to transport of species in the electrolyte solution resulting from dissolution of the oxide film. 相似文献
6.
Core–shell latex particles made of a poly(butyl methacrylate) (PBMA) core and a thin polypyrrole (PPy) shell were synthesized
by two-stage polymerization. In the first stage, PBMA latex particles were synthesized in a semicontinuous process by free-radical
polymerization. PBMA latex particles were labeled either with an energy donor or with an energy acceptor, in two different
syntheses. These particles were used in a second stage as seeds for the synthesis of the core–shell particles. The PPy shell
was polymerized around the PBMA core latex in an oxidative chemical in situ polymerization. Proofs for the success of the
core–shell synthesis were obtained using nonradiative energy transfer (NRET) and atomic force microscopy (AFM). NRET gives
access to the rate of polymer chain migration between adjacent particles in a film annealed at a temperature above the glass-transition
temperature T
g of the particles. Slower chain migration of the PBMA polymer chains was obtained with the PBMA–PPy core–shell particles compared
to rate of the PBMA polymer chain migration found with the pure, uncoated PBMA particles. This result is due to the coating
of PBMA by PPy, which hinders the migration of the PBMA polymer chains between adjacent particles in the film. This observation
has been confirmed by AFM measurements showing that the flattening of the latex film surface is much slower for the core–shell
particles than for the pure PBMA particles. This result can again be explained by the presence of a rigid PPy shell around
the PBMA core. Thus, these two complementary methods have given evidence that real core–shell particles were synthesized and
that the shell seriously hinders film formation of the particles in spite of the fact that it is very thin (thickness close
to 1 nm) compared to the size (750 and 780 nm in diameter) of the PBMA core. Transparency measurements confirm the results
obtained by NRET and AFM. When the films are placed at a temperature higher than the T
g of PBMA, the increase in transparency is faster for films made with the uncoated PBMA particles than for films made with
the coated PBMA particles. This result indicates again that the presence of the rigid PPy layer around the PBMA core reduces
considerably the speed at which the structure of the film is modified when heated above the T
g of PBMA.
Received: 02 September 1999 Accepted: 21 December 1999 相似文献
7.
Jutta Scharf Hans-Henning Strehblow Björn Zeysing Andreas Terfort 《Journal of Solid State Electrochemistry》2001,5(6):396-401
Three thiols with three aromatic rings and different structure – terphenyl-4-methanethiol (TPMT), terphenyl-4-thiol (TPT),
and anthracene-2-thiol (AT) – have been used to form self-assembled monolayers (SAM) on vapour-deposited and flame-annealed
Au films on glass substrates. All three SAMs effectively block the anodic formation of Au oxide, indicating densely packed
layers which prevent the access of water and hydrated ions through the organic layer to the metal surface. The film improves
its inhibiting properties with duration of exposure to the thiol solutions, reaching completion after 1 hour [1]. The charge-transfer
reaction of the Fe(CN)6
3–/Fe(CN)6
4– system is blocked for TPMT films with an insulation of the π-electron system from the Au surface by the methylene group.
TPT and especially AT films show the current density of the redox reactions. It is proposed that the charge transfer occurs
via the aromatic molecules of the SAMs to the Au surface.
Electronic Publication 相似文献
8.
A highly sensitive hydroxylamine (HA) electrochemical sensor is developed based on electrodeposition of gold nanoparticles
with diameter of 8 nm on the pre-synthesized polypyrrole matrix and formed gold nanoparticles/polypyrrole (GNPs/PPy) composite
on glassy carbon electrode. The electrochemical behavior and electrocatalytic activity of the composite-modified electrode
are investigated. The GNPs/PPy composite exhibits a distinctly higher electrocatalytic activity for the oxidation of HA than
GNPs with twofold enhancement of peak current. The enhanced electrocatalytic activity is attributed to the synergic effect
of the highly dispersed gold metal particles and PPy matrix. The overall numbers of electrons involved in HA oxidation, the
electron transfer coefficient, catalytic rate constant, and diffusion coefficient are investigated by chronoamperometry. The
sensor presents two wide linear ranges of 4.5 × 10−7–1.2 × 10−3 M and 1.2 × 10−3–19 × 10−3 M with the detection limit of 4.5 × 10−8 M (s/n = 3). In addition, the proposed electrode shows excellent sensitivity, selectivity, reproducibility, and stability properties. 相似文献
9.
Jing-Jing Yu Shuang Lu Jiang-Wen Li Fa-Qiong Zhao Bai-Zhao Zeng 《Journal of Solid State Electrochemistry》2007,11(9):1211-1219
This study reports the preparation and characterization of gold nanoparticles deposited on amine-functioned hexagonal mesoporous
silica (NH2–HSM) films and the electrocatalytic oxidation of glucose. Gold nanoparticles are fabricated by electrochemically reducing
chloroauric acid on the surface of NH2–HSM film, using potential step technology. The gold nanoparticles deposited have an average diameter of 80 nm and show high
electroactivity. Prussian blue film can form easily on them while cycling the potential between −0.2 and 0.6 V (vs saturated
calomel electrode) in single ferricyanide solution. The gold nanoparticles loading NH2–HSM-film-coated glassy carbon electrode (Au–NH2–HSM/GCE) shows strong catalysis to the oxidation of glucose, and according to the cathodic oxidation peak at about 0.16 V,
the catalytic current is about 2.5 μA mM−1. Under optimized conditions, the peak current of the cathodic oxidation peak is linear to the concentration of glucose in
the range of 0.2 to 70 mM. The detection limit is estimated to be 0.1 mM. In addition, some electrochemical parameters about
glucose oxidation are estimated. 相似文献
10.
Electrically conducting polypyrrole (PPy) film doped with silicomolybdate (SiMo12
or SiMo12) was synthesized by electrochemical polymerization. The synthesized film is capable of fast charge propagation during redox
reactions in strong acid medium 0.2 M H2SO4 solution. Electrochemical quartz crystal microbalance was used to study the mechanism and amount of SiMo12 doped in the PPy matrix. The modified electrode surface was characterized by using atomic force microscope technique, and
it was found that the minimum and maximum globule size were estimated to be in the range of 50–200 nm. The thickness of film
was measured to be approximately 30 ± 10 nm. The modified electrode shows electrocatalytic activity towards reduction of Cr(VI)
and periodate. The rate constant and optimal film thickness were determined for electrocatalytic reduction of Cr(VI) by using
rotating disc electrode experiment. Analytical characterization of the SiMo12 doped PPy film modified electrode was demonstrated by flow injection analysis (FIA) technique and shows good stability for
16 continuous injections for Cr(VI) reduction with RSD of 1.6%. 相似文献
11.
The influence of hydrogen sulfide (10–100 mg/1) on the Armco iron anodic dissolution in an aerated 0.17 M Na2SO4 solution is investigated. During a potentiostatic anodic polarization, the hydrogen sulfide introduction makes the current
increase stepwise. The magnitude of the increase depends on the duration of preliminary anodic polarization, electrode potential,
and hydrogen sulfide concentration. The anodic metal dissolution activation by hydrogen sulfide is explained by chemical conversion
of the oxide-hydroxide passivating film into iron sulfide that is generated at the metal surface in the form of a porous film
and does not hinder the electrode dissolution.
Dedicated to the ninetieth anniversary of Ya.M. Kolotyrkin’s birth. 相似文献
12.
Allan Hallik Ants Alumaa Väino Sammelselg Jüri Tamm 《Journal of Solid State Electrochemistry》2001,5(4):265-273
Polypyrrole/dodecylsulfate (PPy/DDS) films were synthesized in aqueous and ethanolic solutions and investigated in aqueous,
ethanolic, methanolic and acetonitrile solutions by cyclic voltammetry (CV). The amounts of anions and cations in the films
before and after electrochemical treatment were determined by electron probe microanalysis (EPMA); the film morphology was
studied by scanning electron microscopy (SEM). The results prove that the mobility of bulky DDS– ions in PPy increases in the order: water<acetonitrile<ethanol<methanol. It was found that dopant DDS– ions can be easily removed from PPy matrix swollen in alcohols or acetonitrile by electrochemical reduction or by soaking
in electrolyte solutions of these solvents. The influence of electrochemical treatment on the change of doping level in aqueous
solution is essentially less and depends on the cations in the test solution. Although the electroneutrality of PPy/DDS films
during redox cycling is realized mainly by movement of the cations in aqueous solution and by movement of the anions in organic
solvents, nevertheless the participation of anions in aqueous and cations in organic solvents is also established. The redox
properties of PPy/DDS are more dependent on the solvent of the test solutions than of the synthesis solutions.
Electronic Publication 相似文献
13.
Poly(vinylferrocenium) perchlorate–polyaniline (PVF+–PANI) composite film was synthesized electrochemically on Pt electrode in a methylene chloride solution containing a mixture
of poly(vinylferrocene) (PVF) polymer and aniline monomer. PVF+ polymer in the composite film was used as an electron transfer mediator. The composite coating showed significant electrochemical
activity towards hydroquinone (HQ) at pH 4, with high sensitivity and a wide linearity range. The interaction of HQ with PVF+ and PANI homopolymer films was investigated electrochemically and spectroscopically. HQ molecules are accumulated on the
electrode surface due to trapping by both polymers in the composite film and then oxidized catalytically by PANI. The most
significant contribution of PVF+ polymer is that it facilitates electron transfer in the composite film. The linear response range was found to be between
1.60 × 10−4 mM and 115 mM (R
2 = 0.999) at 0.45 V vs saturated calomel electrode. The limit of detection (LOD) was 4.94 × 10−5 mM. 相似文献
14.
Željka Petrović Nushe Lajçi Mirjana Metikoš-Huković Ranko Babić 《Journal of Solid State Electrochemistry》2011,15(6):1201-1207
The study of barrier and semiconducting properties of anodically formed oxide films on chromium in an acid solution was carried
out using the Cr-quartz crystal electrode. The oxide film formation and growth occur through an anion vacancies transport
via a low-field-assisted mechanism (H = 106 V cm−1). The anion diffusion coefficient, which quantitatively describes the transport of point defects within the growing film,
was calculated from capacitance data using the Nernst-Planck equation for low-field limit approximation and Mott-Schottky
analysis. The depletion region in the passive film, close to the film|electrolyte interface, dominates the semiconducting
properties. The passive film on Cr in an acid solution behaves as an n-type semiconductor. An energy-band structure model
of the passive film is given. 相似文献
15.
Conducting polymer poly(pyrrole) (PPy) doped with Nafion was successfully used as ion-to-electron transducer in the construction
of a solid-contact Pb2+-selective polymeric membrane electrode. The Nafion dopant can effectively increase the capacitance of the conducting polymer
and improve the mechanical robustness of the coating. The transducer layer, PPy-Nafion, characterized by cyclic voltammetry
and electrochemical impedance spectroscopy, exhibits a sufficiently high bulk (redox) capacitance and fast ion and electron
transport process. The new Pb2+-selective polymeric membrane electrode, based on PPy-Nafion film as solid contact, shows stable Nernstian characteristics
in Pb(NO3)2 solution within the concentration range of 1.0 × 10−7–1.0 × 10−3 M, and the detection limit is 4.3 × 10−8 M. The potential stability of the electrode and the influence of the interfacial water layer were also evaluated by chronopotentiometry
and potentiometric water layer test, respectively. The results show that the solid-contact Pb2+-selective electrode, based on PPy-Nafion film as ion-to-electron transducer, can effectively overcome the potential drift
and reduce the water layer between the PPy-Nafion transducer layer and the ion-selective membrane. 相似文献
16.
The electrochemical behaviour of some Ni γ-monosubstituted dibenzotetraaza [14] annulene complexes has been investigated. The oxidation in CH2Cl2 of the complex containing a 4-carboxybenzyl group leads to the corresponding γ-γ dimer whose electrochemical properties have been studied. The electrode surface can be coated by thin films of this dimer using CH3CN instead of CH2Cl2; however, the resulting modified electrode is poorly stable. The oxidation of the complex containing 1-(4-carboxybenzyl)pyrrole as γ substituent involves γ-γ dimer formation before the formation of a regular polypyrrole film. The film displays reversible electrochemical reduction of the metal centre (Ni(II)/Ni(I)) and two successive oxidations of the macrocycle (Mc/Mc•+ and Mc•+/Mc2+). The complex containing a bromo(4-carboxybenzyl) group offers an unusual feature in that polymeric films can be obtained following an original procedure based on alternated dimerizations. This is a consequence of the formation of two different dimers obtained by anodic and cathodic processes. 相似文献
17.
I. John Berlin J. S. Lakshmi S. Sujatha Lekshmy Georgi P. Daniel P. V. Thomas K. Joy 《Journal of Sol-Gel Science and Technology》2011,58(3):669-676
Transparent nanocrystalline zirconia thin films were prepared by sol–gel dip coating technique using Zirconium oxychloride
octahydrate as source material on quartz substrates, keeping the sol at room temperature (SET I) and 60 °C (SET II). X-ray
diffraction (XRD) pattern shows the formation of mixed phase [tetragonal (T) + monoclinic (M)] in SET I and a pure tetragonal
phase in SET II ZrO2 thin films annealed at 400 °C. Phase transformation from tetragonal to monoclinic was achieved in SET II film annealed at
500 °C. Atomic force microscopy analysis reveals lower rms roughness and skewness in SET II film annealed at 500 °C indicating
better optical quality. The transmittance spectra gives a higher average transmittance >85% (UV–VIS region) in SET II films.
Optical spectra indicate that the ZrO2 films contain direct—band transitions. The sub- band in the monoclinic ZrO2 films introduced interstitial O−defect states above the top of the valance band. The energy bandgap increased (5.57–5.74 eV) in SET I films and decreased
(5.74–5.62 eV) in SET II films, with annealing temperature. This is associated with the variations in grain sizes. Photoluminescence
(PL) spectra give intense band at 384 and 396 nm in SET I and SET II films, respectively. A twofold increase in the PL intensity
is observed in SET II film. The “Red” shift of SET I films and “Blue” shift of SET II films with annealing temperature, originates
from the change of stress of the film due to lattice distortions. 相似文献
18.
Michael Hyde Andrew J. Saterlay Shelley J. Wilkins John S. Foord Richard G. Compton Frank Marken 《Journal of Solid State Electrochemistry》2002,6(3):183-187
Nanofilm deposits of a porous Sn(IV) oxide are formed by anodic electrodeposition on a polished boron-doped diamond electrode
immersed in an aqueous Sn2+ solution. Mechanically and electrochemically stable deposits of 10–15 nm thickness are formed irrespective of the Sn2+ concentration and mass-transport enhancement by power ultrasound. Atomic force microscopy images indicate the presence of
a smooth and noncrystalline film, which is stable under ambient conditions. n-type semiconducting characteristics are observed
for the aqueous solution redox couples Fe(CN)6
3–/4– and Ru(NH3)6
3+/2+. However, preliminary results from voltammetric experiments indicate that the small and neutral organic molecule N,N,N′,N′-tetramethylphenylenediamine is able to diffuse through the porous film to undergo oxidation directly at the surface of the
boron-doped diamond electrode.
Electronic Publication 相似文献
19.
S. Komiyama E. Tsuji Y. Aoki H. Habazaki M. Santamaria F. Di Quarto P. Skeldon G. E. Thompson 《Journal of Solid State Electrochemistry》2012,16(4):1595-1604
The growth behavior of amorphous anodic films on Ta–Nb solid solution alloys has been investigated over a wide composition
range at a constant current density of 50 A m−2 in 0.1 mol dm−3 ammonium pentaborate electrolyte. The anodic films consist of two layers, comprising a thin outer Nb2O5 layer and an inner layer consisting of units of Ta2O5 and Nb2O5. The outer Nb2O5 layer is formed as a consequence of the faster outward migration of Nb5+ ions, compared with Ta5+ ions, during film growth under the high electric field. Their relative migration rates are independent of the alloy composition.
The formation ratio, density, and capacitance of the films show a linear relation to the alloy composition. The susceptibility
of the anodic films to field crystallization during anodizing at constant voltage increases with increasing niobium content
of the alloy. 相似文献
20.
Franco Varsano Francesca Decker Enrico Masetti 《Monatshefte für Chemie / Chemical Monthly》2001,15(2):83-95
Ce-V mixed oxide films have been deposited by RF sputtering with the aim of increasing the Li charge capacity of counter electrodes in smart windows. Such mixed oxides have shown high transmittance and optical passivity in the visible region. After electrode pre-conditioning by cyclic voltammetry, a good electrochemical reversibility in LiClO4– propylene carbonate electrolyte was observed, and large Li-charge capacity under galvanostatic charging (up to 50 mCċcm−2) has been measured. The electrode charge capacity decreased after prolonged insertion-deinsertion cycles, whereas the photoptic transmittance remained about constant. After 800 cycles the Li-charge capacity decreased to 40 mCċcm−2. The Li diffusion coefficient inside the films measured by electrochemical impedance and by galvanostatic titration ranged from 10−11 cm2ċs−1 to 10−13cm2ċs−1. We observed that the Li charge capacity of the film electrodes is a function of the film deposition conditions, because it increased with the vanadium oxide concentration in the target and with the oxygen content in the sputtering atmosphere. 相似文献