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1.
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
2.
E. P. Surovoi N. V. Borisova 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(13):2302-2307
The gravimetric and optical spectroscopic methods reveals that light irradiation with λ = 300–750 nm and intensity I = 6.9 × 1014–1.1 × 1016 quanta cm−2 s−1 for τ = 1–160 min in atmospheric conditions significantly changes the absorption and reflection spectra and mass of aluminum
films (d = 2–200 nm). The kinetic curves of the degree of conversion versus aluminum film thickness are satisfactorily described in
the inverse logarithmic and parabolic terms. The contact potential difference is measured for Al and Al2O3 films along with the photo-EMF of Al-Al2O3 systems. The suggested model includes the stages of generation and redistribution of nonequilibrium charge carriers in the
contact field of Al-Al2O3 systems, oxygen adsorption, Al3+ diffusion, and Al2O3 formation. 相似文献
3.
Mechanism of aluminium and oxygen ions transport in the barrier layer of porous anodic alumina films
Aluminium was anodised in oxalic acid electrolyte at concentrations 0.125–0.5?M, current densities 25–100?A?m?2 and low temperatures 0 and 5?°C. The efficiencies of Al consumption and oxide production in the metal|oxide interface and the transport numbers of Al3+ and O2? in the barrier layer of porous anodic alumina films were determined. The Al consumption efficiency essentially coincides with that by Faraday’s law while that of oxygen evolution, visually detected at these temperatures, is negligible. The oxide production efficiency and O2? transport number decrease with temperature, increase with current density and are almost independent of electrolyte concentration. The transport numbers combined with literature ones for oxalate and sulphuric acid electrolytes were treated by high field kinetic equations describing independent Al3+ and O2? transport to penetrate its mechanism. The half jump activation distances were found comparable to ions radii. This mechanism embraces two steps, equilibrium established between ordinary oxide lattice hardly allowing transport and locally emerging transformed structure dispersed in barrier layer consisting of pairs of Al3+ and O2? clusters enabling transport and the rate-controlling step of actual ion transport within clusters. The transformed structure then returns to ordinary while it emerges at other sites. The real activation energy of Al3+ transport is higher than that of O2?, e.g. by ≈?19?kJ?mol?1 at low current densities, but the fraction of really mobile Al3+ is ≈?103–104 times larger than that of O2? justifying the not excessively different values of O2? and Al3+ transport numbers. 相似文献
4.
The Er3+-doped Al2O3 nanopowders have been prepared by the sol-gel method, using the aluminium isopropoxide [Al(OC3H7)3]-derived γ-AlOOH sols with addition of the erbium nitrate [Er(NO3)3·5H2O]. The five phases of γ-(Al,Er)2O3, θ-(Al,Er)2O3, α-(Al,Er)2O3, ErAlO3, and Al10Er6O24 were detected with the 0–20 mol% Er3+-doped Al2O3 nanopowders at the different sintering temperature of 600–1200°C. The average grain size was increased from about 5 to 62 nm
for phase transformation of undoped γ-Al2O3→α-Al2O3 at the sintering temperature from 600 to 1200°C. At the same sintering temperature, average grain size was decreased with
increase of the Er3+ doping concentration. Infrared absorption spectra of γ-Al2O3 and θ-Al2O3 nanopowders showed the two broad bands of 830–870 and 550–600 cm−1, the three broad bands of 830–870, 750–760, and 550–600 cm−1, respectively. The infrared absorption spectra for the α-Al2O3 nanopowder showed three characteristic bands, 640, 602, and 453 cm−1. The two characteristic bands of 669 and 418 cm−1 for Er2O3 clusters were observed for the Er3+-doped Al2O3 nanopowders when Er3+ doping concentration was increased up to 2 mol%. The 796, 788, 725, 692, 688, 669, 586, 509, 459, and 418 cm−1 are the characteristic bands of Al10Er6O24 phase. 相似文献
5.
Georgios Patermarakis Konstantinos Moussoutzanis Nikolaos Nikolopoulos 《Journal of Solid State Electrochemistry》1999,3(4):193-204
A new method has been developed capable of describing the incorporation of electrolyte anions along the pore wall surface
and across both the barrier layer and the pore wall oxide after the establishment of the steady state of growth of porous
anodic Al2O3 where other methods cannot be applied to obtain reliable results. The knowledge of the nature/composition of anodic oxides
as regards the incorporation of species like electrolyte anions is of specific importance for both the understanding of the
electrochemical mechanism of oxide production and growth and the scientific and technological applications of porous anodic
Al2O3 films. The method consists of the selection and use of a suitable catalytic probe reaction on porous anodic oxides at thicknesses
varying from a value near zero up to the maximum limiting thickness and the treatment of the experimental reaction rate results
by a properly developed mathematical formalism. This method was employed in anodic Al2O3 films prepared in H2SO4 anodizing electrolyte at a constant bath temperature and different current densities using as a probe reaction the decomposition
of HCOOH on these oxides, which is almost exclusively a dehydration reaction, at relatively high reaction temperatures, 350 °C
and 390 °C, where the effect of other species except SO4
2− incorporated in the oxide on the reaction rate is eliminated. It has been shown that the fraction of the intercrystallite
surfaces occupied by SO4
2− follows a parabola-like distribution. It has a significant value at the pore base surface, depending on the current density,
then it passes through a maximum along the pore wall surface and across both the barrier layer and the pore walls near the
pore bases at positions depending on the current density and then becomes almost zero at the mouths of the pores of the oxide
with the maximum limiting thickness and at both the Al2O3/Al interface and cell boundaries. The maximum value of the surface coverage is almost independent of the current density
and is always near 1, showing an almost complete saturation of intercrystalline surfaces at these positions. The above distribution
of surface coverage predicts a qualitatively similar distribution of the SO4
2− bulk concentration across both the barrier layer and pore wall oxide around the pore bases. The method may be improved and
developed further either for a more detailed investigation of the above films or to investigate films prepared in other pore-forming
electrolytes.
Received: 30 July 1998 / Accepted: 30 September 1998 相似文献
6.
G. N. Mazo N. V. Lyskov A. V. Lezhepekov L. S. Leonova 《Russian Journal of Electrochemistry》2010,46(3):297-305
The conditions of formation of electrode/electrolyte interfaces LaSrCuO4 − δ|Ce0.9Gd0.1O2 − δ are optimized. It is shown that electrode layers formed by the screen printing method have better developed surfaces and
are more uniform and strong as compared with thick film layers applied by a brush. Symmetric LaSrCuO4 − δ|Ce0.9Gd0.1O2 − δ|LaSrCuO4 − δ cells with porous electrodes are studied by impedance spectroscopy and cyclic voltammetry in the temperature range of 773–1173
K at the oxygen partial pressure of (28–2.1) × 104 Pa. The oxygen process is shown to be limited by the charge transfer across the electrode/electrolyte interface. The exchange
currents are calculated in the temperature range of 773–1173 K to amount from 1 × 10−3 to 3.5 × 10−2 A/cm2, which points to the high reversibility of the electrode/electrolyte interface with respect to oxygen. 相似文献
7.
G. Patermarakis J. Chandrinos K. Masavetas 《Journal of Solid State Electrochemistry》2007,11(9):1191-1204
A holistic model for the kinetics of steady state growth of porous anodic alumina films in oxalic acid, H2C2O4, solution was developed not necessarily requiring the adoption of any ‘a priori’ mechanism of porous film growth. By this
model the effect of anodising conditions on the transport numbers of Al3+ cations and O2− anions across the barrier layer was revealed. The cation (anion) transport number decreased (increased) with current density,
increased (decreased) with temperature and was unaffected by the concentration of electrolyte or pH. A complementary atomistic-ionic
kinetic model was developed that fully justified these results and showed that the activation distances of Al3+ and O2− transport are comparable, but the activation energy of Al3+ transport is lower mainly due to the much smaller size of Al3+. The validity of the model was tested on the basis of SEM observations, while structural features and the rate of pore wall
dissolution were determined. 相似文献
8.
Electrical characterization of poly(3-methylthiophene) electrosynthesized onto a tin-oxide substrate
R. Valaski A. F. Bozza L. Micaroni I. A. Hümmelgen 《Journal of Solid State Electrochemistry》2000,4(7):390-393
We have investigated poly(3-methylthiophene) (PMeT) thin films electrochemically synthesized directly onto a tin-oxide (TO)
electrode. We find that the PMeT film thickness depends linearly on the charge density used during the electropolymerization.
We have demonstrated that the current transport in PMeT films (solid phase) is space-charge limited or controlled by thermionic
emission, depending on the electrode material. Using TO/PMeT/Ni devices we estimate the positive charge carrier mobility in
PMeT to be around 4 × 10−4 cm2 V−1 s−1, and the potential barrier height for positive charge carrier injection at the Al/PMeT interface to be 0.17 eV.
Received: 6 December 1999 / Accepted: 24 February 2000 相似文献
9.
V. Yu. Tregubenko I. E. Udras V. A. Drozdov A. S. Belyi 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2009,83(12):2039-2044
The formation of highly imperfect γ-Al2O3 oxide prepared by calcining pseuodoboehmite and plasticized by organic acids was studied. The nature of the organic acid-aluminum
hydroxide plasticizer was found to substantially influence the degree of γ-Al2O3 structure imperfection estimated qualitatively as the difference between the X-ray structural density and effective density
with respect to helium and aluminum oxide. A high degree of imperfection caused an increase in the intensity of the absorption
band at 3775 cm−1 corresponding to OH groups localized on five-coordinate Al3+ and the concentration of Lewis acid centers. The adsorption and catalytic properties of systems based on these carriers were
studied. 相似文献
10.
A. A. Solov’ev N. S. Sochugov A. V. Shipilova K. B. Efimova A. E. Tumashevskaya 《Russian Journal of Electrochemistry》2011,47(4):494-502
Data on the mid-temperature solid-oxide fuel cells (SOFC) with thin-film ZrO2-Y2O3 (YSZ) electrolyte are shown. Such a fuel cell comprises a carrying Ni-YSZ anode, a YSZ electrolyte 3–5 μm thick formed by
vacuum ion-plasma methods, and a LaSrMnO3 cathode. It is shown that the use of a combined method of YSZ electrolyte deposition, which involves the magnetron deposition
of a 0.5–1.5-μm thick sublayer and its pulse electron-beam processing allows a dense nanostructured electrolyte film to be
formed and the SOFC working temperature to be lowered down as the result of a decrease in both the solid electrolyte Ohmic
resistance and the Faradaic resistance to charge transfer. SOFC are studied by the methods of voltammentry and impedance spectroscopy.
The maximum power density of the SOFC under study is 250 and 600 mW/cm−2 at temperatures of 650 and 800°C, respectively. 相似文献
11.
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
12.
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
13.
Rika M. Y. A. Rahman M. M. Salleh A. A. Umar A. Ahmad 《Journal of Solid State Electrochemistry》2010,14(11):2089-2093
A nanoparticle TiO2 solid-state photoelectrochemical cell has been fabricated. The effect of ionic conductivity of a solid electrolyte of polyacrylonitrile
(PAN)–propylene carbonate (PC)–lithium perchlorate (LiClO4) on the performance of a photoelectrochemical cell of indium tin oxide (ITO)/TiO2/PAN–PC–LiClO4/graphite has been investigated. A nanoparticle TiO2 film was deposited onto ITO-covered glass substrate by controlled hydrolysis technique. A solid electrolyte of PAN–LiClO4 with PC plasticizer prepared by solution casting technique was used as a redox couple medium. The room temperature conductivity
of the electrolyte was determined by AC impedance spectroscopy technique. A graphite electrode was prepared onto a glass slide
by electron beam evaporation technique. The device shows a photovoltaic effect under illumination. The short-circuit current
density, J
sc, and open-circuit voltage, V
oc, vary with the conductivity of the electrolyte. The highest J
sc of 2.82 μA cm−2 and V
oc of 0.56 V were obtained at the conductivity of 4.2 × 10−4 Scm−1 and at the intensity of 100 mW cm−2. 相似文献
14.
Franco Varsano Francesca Decker Enrico Masetti 《Monatshefte für Chemie / Chemical Monthly》2001,132(1):83-95
Summary. 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.
Received June 23, 2000. Accepted (revised) August 7, 2000 相似文献
15.
Kiyoharu Tadanaga Akira Miyata Daisuke Ando Naoko Yamaguchi Masahiro Tatsumisago 《Journal of Sol-Gel Science and Technology》2012,62(1):111-116
Using hot water treatment of sol–gel derived precursor gel films, Co–Al and Ni–Al layered double hydroxide (LDH) thin films
were prepared. The precursor gel films of Al2O3–CoO or Al2O3–NiO were prepared from cobalt or nickel nitrates and aluminum tri-sec-butoxide using the sol–gel method. Then, the precursor gel films were immersed in a NaOH aqueous solution of 100 °C. Nanocrystallites
of Co–Al and Ni–Al LDH were precipitated with the hot water treatment with NaOH solution. The largest amounts of nanocrystals
were obtained with a solution of pH = 10 for Co–Al LDH, and with that of pH = 9 for Ni–Al LDH. X-ray diffraction measurements
confirmed that this process formed CO3
2− intercalated LDHs. Both Co–Al and Ni–Al LDH thin films were confirmed to work as electrodes for electrochemical devices by
cyclic voltammogram measurements. 相似文献
16.
Tian Yongmei Huang Jichun Gao Yuan Cao Dianxue Wang Guiling 《Journal of Solid State Electrochemistry》2012,16(5):1901-1906
Fe–N–C catalysts were prepared through metal-assisted polymerization method. Effects of carbon treatment, Fe loading, nitrogen
source, and calcination temperature on the catalytic performance of the Fe–N–C for H2O2 electroreduction were measured by voltammetry and chronoamperometry. The Fe–N–C catalyst shows optimal performance when prepared
with pretreated active carbon, 0.2 wt.% Fe, paranitroaniline (4-NA) and one-time calcination. The Fe–N–C catalyst displayed
good performance and stability for electroreduction of H2O2 in alkaline solution. An Al–H2O2 semi-fuel cell was set up with Fe–N–C catalyst as cathode and Al as anode. The cell exhibits an open-circuit voltage of 1.3 V
and its power density reached 51.4 mW cm−2 at 65 mA cm−2. 相似文献
17.
Liquid-phase reduction NO
3
−
using monometallic and bimetallic catalysts (5% Rh/Al2O3, 5% Rh-0.5% Cu/Al2O3, 5% Rh-1.5% Cu/Al2O3, 5% Rh-5% Cu/Al2O3 and a physical mixture of 5% Rh/Al2O3 and 1.5% Cu/Al2O3) was studied in a slurry reactor operating at atmospheric pressure. Kinetic measurements were performed for a low concentration
of nitrate (0.4 × 10−3−3.2 × 10−3 mol dm−3) and the temperature range 293–313 K. From the experimental data, it was found that the reduction of nitrate is first order
with respect to nitrate. On the basis of the rate constants, the apparent activation energy was established using a graphic
method.
Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 6, pp. 881–886.
This article was submitted by the authors in English. 相似文献
18.
G. A. Vorob'eva E. V. Gal'tseva A. V. Kozintsev A. I. Prokofev A. A. Dubinskii 《Russian Chemical Bulletin》1998,47(11):2155-2159
The kinetics of sequential generation of mono-, bi-, and triradical centers in heterogeneous reactions of toluene solutions
of orthoquinones, catechols, and their mixtures with γ-Al2O3 was studied. The localization of mono- and biradical centers on the solid oxide surface and the transfer of triradical Al3+ (Q−)3 complexes (Q− is the corresponding 3,6-di-tert-butylsemiquinone radical) to a solution (extraction of Al from the solid phase) were proved. The number of the triradical
complexes extracted is considerably higher than that of active surface centers accessible for coordination with radical ligands.
The conditions favoring the formation of the radical complexes on the Al ions were established. Possible mechanisms of these
processes were proposed.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2223–2227, November, 1998. 相似文献
19.
G. Patermarakis K. Moussoutzanis J. Chandrinos 《Journal of Solid State Electrochemistry》2001,6(1):39-54
The kinetics of growth of porous anodic alumina films in pure H2SO4, in mixtures of H2SO4 and Al2(SO4)3 and in Al(HSO4)3, NaHSO4 and KHSO4 electrolytes were studied. The latent physicochemical processes at the pore base surface/electrolyte interface, across the
barrier layer, inside the metal/oxide interface and at the pore wall surface/electrolyte interface and their mechanisms were
revealed. High field strength equations were formulated describing the ionic migrations from the pore base surface. These
showed that, at constant current density and temperature, the inverse of the pore base square diameter depends linearly on
the inverse of the H+ activity in the anodizing solution and that this diameter increases with H+ activity, in agreement with the experimental results. The mechanism of electrolyte anion incorporation inside the barrier
layer and the real distribution of the anion concentration across both the barrier layer and pore walls were deduced. The
effects of the different kinds and concentrations of the electrolyte anions and cations on both the above processes and their
mechanisms were also examined.
Electronic Publication 相似文献
20.
Poly(amidoamine) dendrimer (Generation-4) encapsulated platinum nanoparticles (PtNP-PAMAM) were prepared and used to fabricate
nanocomposites with Keggin-type phosphotungstic acid (PW12O403−) using a layer by layer electrostatic assembly technique. Indium tin oxide (ITO) electrodes, which were first modified with
a monolayer of 3-aminopropyl triethoxysilane (3-APTES), were used as substrates for assembly of the PW12O403− monolayer. Nanocomposites were then fabricated by depositing PtNP-PAMAM on the monolayer of PW12O403−. The amount of PtNP-PAMAM deposited was controlled by using different concentrations of PtNP-PAMAM diluted in 0.1 M H2SO4 solution. The hydrogen evolution reaction (HER) was used to test electrocatalytic activities of these nanocomposite modified
electrodes. Modification of ITO|3-APTES with PW12O403− |PtNP-PAMAM showed significantly higher electrocatalytic activities toward the HER than electrodes modified with either PW12O403− or PtNP-PAMAM alone. The electrocatalytic activities were found to depend on the composition of PtNP-PAMAM and PW12O403− on electrode surfaces, which was attributed to an interaction between these species. Heat treatment of ITO|3-APTES|PW12O403− |PtNP-PAMAM electrodes at 200 °C produced significantly higher electrocatalytic activities, which supported the suggestion
of an interaction.
Presented at the 4th Baltic conference on Electrochemistry, Griefswald, March 13.−16., 2005. 相似文献