共查询到20条相似文献,搜索用时 31 毫秒
1.
Oktawian Makowski Dorota Szymanska Krzysztof Miecznikowski Marcin A. Malik 《Electrochimica acta》2007,53(3):1235-1243
The ability of 4-(pyrrole-1-yl) benzoic acid (PyBA) to form monolayer-type carboxylate-derivatized ultra-thin organic films on solid electrode surfaces was explored here to attract coordinatively and immobilize Ni2+ ions at the electrode/electrolyte interface. In the next step, the system was exposed to Fe(CN)63− or Fe(CN)64− solution to form a robust nickel hexacyanoferrate (NiHCF) layer. By repeated and alternate treatments in solutions of PyBA, Ni2+ cations, and Fe(CN)63− or Fe(CN)64− anions, the amount of the material could be increased systematically in a controlled fashion to form three-dimensional multilayered NiHCF-based assemblies. The layer-by-layer method was also extended to the growth of hybrid conducting polymer stabilized NiHCF films in which the initial PyBA-anchored NiHCF layer (formed on glassy carbon) was subsequently exposed (a desired number of times) through alternate immersions to the monomer (3,4-ethylenedioxythiophene), Fe(CN)63− and Ni2+ solutions. During voltammetric potential cycling (electropolymerization) in the external supporting electrolyte solution, poly(3,4-ethylenedioxythiophene) or PEDOT linked NiHCF-based multilayered films were produced. They were characterized by good stability and high dynamics of charge transport. 相似文献
2.
In this work, the ion exchange characteristics of poly(butyl viologen) (PBV) thin films on a platinum electrode has been investigated by cyclic voltammetric (CV) scans. Since ferrocyanide anions (Fe(CN)64−) were added during the polymerization of the PBV thin-film for its stability, Fe(CN)64− could form charge transfer complex with monomer and co-deposited with polymer. Scanning electrochemical microscopy (SECM) was used to probe the released Fe(CN)64− ions from PBV film with Os(bpy)3Cl2 as a mediator for the approaching process in 0.5 M KCl medium. Mass changes during the redox process of the film were also monitored in-situ by electrochemical quartz crystal microbalance (EQCM). The ion exchange and transport behavior was observed during CV cycling of the film of the SECM and EQCM. The insertion and extraction of anions were found to be potential-dependence. Moreover, the decrease in tip current of released Fe(CN)64− with increasing cycle number accounted for the ion exchange between Fe(CN)64− and Cl− in the KCl electrolyte. However, the Fe(CN)64−/Fe(CN)63− redox couple was found to be highly stable between 0.0 and 0.5 V (vs. Ag/AgCl/saturated KCl) in the phosphate buffer solution. Therefore, the electrochemical property of Fe(CN)64−/Fe(CN)63− redox couple was studied at different scan rates using CV technique. The peak currents were directly proportional to the scan rate as predicted for a surface confined diffusionless system. The surface coverage (Γ) and the concentration of Fe(CN)64− were determined to be 1.88 × 10−8 mol/cm2 and 0.641 mol/dm3, respectively. By neglecting cations incorporation during redox reaction of the PBV film and also based on the results obtained from energy-dispersive X-ray spectroscopy for the films of as-deposited, reduced and oxidized states, an ion exchange mechanism was proposed. 相似文献
3.
《Electrochimica acta》1986,31(5):549-553
The Fe(CN)3−/4−6 charge-transfer reaction was studied with anion-exchange polymer-coated electrodes SO2−4 and ClO−4 were mainly used as the anions of the background electrolyte. The electrochemical results are correlated with the equilibrium distribution of the ions between the electrolyte and the coating. Since the considered anions are ir-active their concentration in the film could be determined by ir-reflection-absorption spectroscopy, after the coated electrodes had been withdrawn from the electrolyte. The strong influence of the films' ion-exchange selectivity on the electrode behaviour is demonstrated. 相似文献
4.
Samaneh Mozaffari Mohammad Reza Nateghi Abbas Behjat Mahmood Borhani-Zarandi 《Iranian Polymer Journal》2012,21(11):799-808
Schottky-barrier diode devices were fabricated in a sandwich configuration with poly(pyrrole-co-indole) copolymer semiconducting films prepared by electropolymerization. Effect of different dopants of ClO4 ?, BF4 ?, C7H7SO3 ? and [Fe(CN)6]3? on the electronic properties of the fabricated devices was followed using Ag, In, Al and Cu metal junctions. Current?Cvoltage and capacitance?Cvoltage characteristics were recorded for making a comparative evaluation of the electronic and junction properties of the devices. The electrical characteristics of the junctions were analyzed based on the standard thermionic emission theory. Polymer doped by ClO4 ? showed lower reverse saturation currents and ideality factor but higher potential barriers and rectification ratios. Effect of dopant ions and copolymerization on the optical band gaps (E g) of the films were investigated and the optical transmissions of the doped copolymer films were measured in the wavelength range of 250?C900?nm. It was shown that the energy gap of copolymers laid between those of corresponding homopolymers and polyindole (PIN) doped by [Fe(CN6)]?3 had E g less than that of polymer doped by other anions whereas E g of polypyrrole was independent of dopant ions. Also, the morphology of the polymeric films revealed the surface of the PIN doped with ClO4 ? was very smooth which created a good contact with indium metal. 相似文献
5.
The influence of chloride, sulfate and perchlorate anions on the behaviour of native oxide layers on aluminium is investigated using electrochemical techniques. Due to its influence on the open circuit potential and the cathodic side of the polarization curve the oxygen concentration has been carefully controlled. Two kinds of attack on a commercially pure aluminium (99.5 wt %) have been observed. In all the investigated 0.5 M Cl–, 0.5 M ClO–
4 and 0.5 M SO2–
4 aqueous solutions the metal is corroded around the iron and silicon containing precipitates, but only in Cl– and ClO–
4 solutions is crystallographic pitting observed. Comparison with high purity aluminium (99.99 wt %) shows that pitting corrosion is not influenced by the presence of impurities in the aluminium alloys, but by the presence of anions in solution. The pH and/or oxygen concentration determine whether or not the pitting potential coincides with the corrosion potential. 相似文献
6.
X. Ling M.D. Pritzker C.M. Burns J.J. Byerley 《Journal of Applied Electrochemistry》1999,29(8):1005-1013
A cyclic potential sweep (CPS) technique has been used to form coatings of poly(2-vinylpyridine) on mild steel substrates by electropolymerization of the monomer. This method can produce thick and uniform coatings of much higher quality than can be formed by other electrochemical methods such as galvanostatic electrolysis, constant cell-potential electrolysis and chronoamperometry. The range and rate of the potential sweep during the CPS are important for successful coating formation. Potential sweeps between –1.0 and –2.2 V vs SCE at rates from 10 to 50 mV s–1 have been found to be most suitable for the formation of poly(2-vinylpyridine) coatings. The essential reason for the successful application of the CPS technique to the electropolymerization process is the compatibility of the nature of the CPS process and the mechanism of 2-vinylpyridine electropolymerization. 相似文献
7.
The hydration of layered double hydroxides (LDHs) was investigated by changing the interlayer anion species, the Mg/Al ratio of the LDH hosts and the relative humidity (RH). The anions were CO32−, Cl−, Br−, NO3−, I−, SO42−, and ClO4− (listed in the order of ion size, small to large) and LDHs with Mg/Al = 1.90 (LDH2) and 2.91 (LDH3) were used. Their XRD profiles were measured by an XRD diffractometer while controlling the RH in the range 0–95% at 25 °C. Only I−, SO42−, and ClO4− LDH2s and SO42− LDH3 showed a large step-wise basal-spacing expansion, 0.24–0.28 nm, under high RH conditions (> ca. 60%) probably due to the insertion of one water layer into the interlayer space. Such hydration occurred more favorably for the LDHs with larger anions and those with a higher layer charge (LDH2). Among them, I− and ClO4− LDH2s exhibited the second staging – alternate stacking of hydrated (H) and non-hydrated (NH) interlayers – in the intermediate RH region. 相似文献
8.
Atefeh Moradi Abbas Emamgolizadeh Abdollah Omrani Abbas Ali. Rostami 《应用聚合物科学杂志》2012,125(3):2407-2416
Poly(3,4-ethylenedioxythiophene) (PEDOTh) films were deposited on glassy carbon (GC) electrodes from organic electrolytes containing the monomer in a solution of acetonitrile (AN). The effect of the supporting electrolyte used during electropolymerization, on the redox behavior, surface morphology, and degree of crystallinity of the films has been investigated by FTIR, cyclic voltammetry, and scanning electron microscopy (SEM) techniques. The use of LiPF6 leads to a higher electropolymerization efficiency and an increase of electroactivity and crystallinity of the polymer. On the basis of voltammetric studies of the Nernst and Butler–Volmer equations, we concluded that BF4−, ClO4−, and PF6− anions are the mobile species during the redox process of the PEDOTh films. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
9.
Tereza Afrati Catherine Dendrinou-Samara Curtis M. Zaleski Jeff W. Kampf Vincent L. Pecoraro Dimitris P. Kessissoglou 《Inorganic chemistry communications》2005,8(12):1173-1176
The reaction of copper(II) perchlorate with di-2-pyridyl ketone oxime yields the first 18-MC-6 complex with M–N–O connectivity, [Cu6(pko)6ClO4(CH3CN)6] [Cu6(pko)6(ClO4)3(CH3CN)4] · 8ClO4 · 14CH3CN · H2O 1. In the solid state the cationic complex encapsulates a perchlorate anion within the central cavity. Magnetic susceptibility measurements reveal that the complex is diamagnetic. EPR measurements indicate that the complex dissociates in DMF. 相似文献
10.
H. H. Rehan 《Journal of Applied Electrochemistry》2000,30(8):945-951
Anodic polymerization of the azo dye methoxy red (4-methoxybenzene azo-1,3-diaminobenzene) on platinum electrodes in 1 M HCl in 50% v/v ethanol/water was found to yield thin and stable polymeric films. The films were electroactive in acidic solutions and the activity diminished as the acidity decreased. The pair of symmetrical redox peaks at a formal redox potential, (E
)pH=0 = 0.61 V vs SCE, with a Nernstian slope dE/dpH = 0.06 V, is attributed to a 1:1 proton + electron elimination (on oxidation)/addition (on reduction) at the amino/imino linkages which connect the aromatic nuclei. Chronocoulometric plots indicated that the transport of the solvated protons, and probably Cl– ions, through the film is the rate-determining step of the above redox processes. The rate of electron transfer reactions of the redox couple [Fe(CN)6]3–/4– on poly-methoxy red-covered platinum electrodes decreased by a factor of more than two orders of magnitude, compared to the bare electrodes. 相似文献
11.
A.G. Christy A. Lowe V. Otieno-Alego M. Stoll R.D. Webster 《Journal of Applied Electrochemistry》2004,34(2):225-233
Artificial copper pits were prepared by electrochemically oxidising 60–80 m diameter copper wires embedded in an epoxy resin over periods of 12–14 h. The electrolyte matrix consisted of various combinations of approximately 40 ppm unbuffered solutions (pH = 6–8) of sodium salts of Cl–, HCO3
– and SO4
2– that are similar in concentration to what are found in potable water supplies in many metropolitan areas throughout the world. It was found that in the concentrations used for the study, HCO3
– and to a lesser degree Cl– had a positive affect on preventing pit growth under potentiostatic control, with both anions causing passivation of the copper metal. On the other hand, SO4
2– was found to be very aggressive to copper dissolution and led to the formation of relatively deep pits (about 0.5 mm). Raman microspectroscopic analyses were performed on the freshly prepared undried caps that formed at the top of the pits and allowed the identification of several corrosion products by a comparison with standard copper mineral samples. The most complicated cap structure was observed in the presence of all three anions with distinct regions of the pit corresponding to cuprite (Cu2O), eriochalcite (CuCl2 · 2H2O), atacamite and/or botallackite [Cu2Cl(OH)3] and brochantite [Cu4(SO4)(OH)6]. 相似文献
12.
A. Yasuda H. Mori Y. Takehana A. Ohkoshi N. Kamiya 《Journal of Applied Electrochemistry》1984,14(3):323-327
Electrochromic properties of the mixed solution of n-heptyl viologen dibromide (HV), Fe(CN)
6
4–
and NaH2PO2 or KBr were investigated by cyclic voltammetry and the transparency-time relation. When Fe(CN)
6
4–
is added to a HV solution the mixture colours violet without inputting any voltage. However, the colour fades gradually by further addition of NaH2PO2, and the transparency of the mixture increases with addition of larger amounts of NaH2PO2. The same effect was observed by addition of KBr to the HV-Fe(CN)
6
4–
solution. The input voltage required for the electrochromism of HV is lowered considerably by addition of Fe(CN)
6
4–
, when NaH2PO2 or KBr plays a role in controlling the colouringerasing phenomena. The HV-Fe(CN)
6
4–
-KBr system showed some HV residue in the cyclic voltammogram on an indium-tin oxide (ITO) electrode, while no such HV residue was observed in the HV-Fe(CN)
6
4–
-NaH2PO2 system. The HV-Fe(CN)
6
4–
-NaH2PO2 system is superior in colouring-erasing reproducibility and in response time to the HV solution or the HV-Fe(CN)
6
4–
system. 相似文献
13.
Mohammed A. Amin 《Electrochimica acta》2009,54(6):1857-426
The metastable and stable pitting events of Al were studied in 0.075 M deaerated acidic NaClO3 and NaClO4 solutions (pH 3) using potentiodynamic anodic polarization and potentiostatic measurements, complemented with SEM and XPS examinations of the electrode surface. Metastable pits (appeared here as oscillations in current in the nA range) form at potentials close to the pitting potential (Epit). SEM examinations of the electrode surface showed that the current oscillations resulted in observable pits on sample surface. The repassivated metastable pitting sites are prone to become preferential sites for following metastable pits to nucleate, resulting in accumulated corrosion damages on the surface. Results showed that Cl− ions produced in solution via the reduction of ClO3− and ClO4− anions at sufficiently negative cathodic potentials as well as their decomposition at high anodic potentials. Chloride production induced via the reduction of perchlorates is much slower than induced by chlorates. XPS examinations of the electrode surface showed that the amount of ClO4− and Cl− anions detected on the electrode surface increases with both cathodic and anodic polarizations (even above Epit). Experimental results revealed that addition of Cl− ions to the ClO4− solution accelerates pitting corrosion, indicating that these anions cooperate together in passivity breakdown and initiation of pitting. The role of ClO3− and ClO4− ions, despite their large size, in pitting process is also discussed here. A point defect model (PDM) is employed to explain passivity breakdown induced by pitting corrosion as a result of the aggressive attack of Cl− ions. 相似文献
14.
Functionalized polypyrrole film were prepared by incorporation of (Fe(CN)6)4− as doping anion, during the electropolymerization of pyrrole onto a carbon paste electrode (CPE) in aqueous solution by using potentiostatic method. The electrochemical behavior of the (Fe(CN)6)3−/(Fe(CN)6)4− redox couple in polypyrrole was studied by cyclic voltammetry and double step potential chronoamperometry methods. In this study, an obvious surface redox reaction was observed and dependence of this reaction on the solution pH was illustrated. The electrocatalytic ability of polypyrrole/ferrocyanide films modified carbon paste electrode (Ppy/FCNMCPEs) was demonstrated by oxidation of ascorbic acid. It has been found that under optimum condition (pH 7.00), the oxidation of ascorbic acid at the surface of such electrode occurs at a potential about 540 mV less positive than unmodified carbon paste electrode. The kinetic parameters such as electron transfer coefficient, α and catalytic reaction rate constant, kh′, were also determined by using various electrochemical approaches.The catalytic oxidation peak current showed a linear dependent on the ascorbic acid concentration and a linear calibration curve was obtained in the range of 4.5×10−4 to 9.62×10−3 M of ascorbic acid with a correlation coefficient of 0.9999. The detection limit (2σ) was determined as 5.82×10−5 M. 相似文献
15.
Kasem K. Kasem Franklin A. Schultz 《Journal of Inorganic and Organometallic Polymers》1994,4(4):377-390
Multiply charged electroactive anions [IrCl
6
2–
, Fe(CN)
6
3–
, and W(CN)
8
4–
] are electrostatically incorporated in polymeric films of tris(4-vinyl-4-methyl-2,2-bipyridine) ruthenium(II) [poly-Ru(vbpy)
3
2+
] from aqueous trifluoroacetate solution. Values of apparent diffusion coefficients (D
ct) and heterogenous electron transfer rates (k
et) are measured for these anions as a function of their relative concentration (
M/
Ru) in the film.D
ct andk
et decrease systematically as
M/
Ru increases in a manner that is independent of charge and chemical identity of the ion. This result suggests that a nonchemical process, presumably electrostatic cross-linking, limits diffusional motion and is responsible for the decrease inD
ct andk
et with increasing anion content. Protonated polyvinyl-pyridine films exhibit similar ranges and variations inD
ct andk
et, which suggest similar structures and mechanisms of charge transport for these films and poly-Ru(vbpy)
3
2+
. 相似文献
16.
Electrochemical redox reactions of poly(1,8-diaminocarbazole) (PDACz) films in aqueous (0.1 M HClO4) and nonaqueous (0.1 M LiClO4 in acetonitrile) solutions were studied by cyclic voltammetry, in situ vis/NIR and Raman spectroscopy. It has been demonstrated that spectroelectrochemical behavior of the polymer is strongly dependent on the nature of the solution used for doping-undoping but not on the medium used for electropolymerization. A redox couples Fe2+/Fe3+, Fe(CN)64−/3− and tertrathiafulvalene were used as the probes for the studies of electroactivity of the oxidized polymer films. The results were discussed in terms of different mechanism of deprotonation process of the polymer in aqueous solution of 0.1 M HClO4 and in 0.1 M LiClO4 solution in aprotic acetonitrile and the reaction schemes in the two media are proposed. 相似文献
17.
Wadysaw Walkowiak 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1980,30(1):611-619
An experimental investigation into the batch ion flotation of cobalt complex anions with the cationic surfactant, cetylpyridinium chloride is described. The concentration ratio of cetyl-pyridinium: cobalt in the foam was determined and found to be 2.0–2.7 for CoCl2 plus KCN solution and 3.0–3.3 for K3[Co(CN)6] solution. Spectroscopic measurements of the former anion show that mainly [Co(CN)5H2O]2- anions were floated. The [Co(CN)6]3- flotation was established in the presence of Cl?, Br?, I?, CN?, NO3? and SO42- anions. The accelerating influence of the ion flotation produced by the presence of Cl?, Br?, I?, CN?, NO3? and SO42- increased as their partial molal volume increased. The solvent sublation of [Co(CN)6]3- anions was established in the presence of these anions. 相似文献
18.
The electrochemical behavior of B-doped diamond films on Ti substrates subjected to different pretreatment procedures (annealing, sand-blasting, and etching in HCl) is evaluated as a function of surface microroughness. Generally, the differential capacitance follows the true surface area of the electrodes. The width of the potential window also increases, but slightly, with the roughness. The electrode reversibility in the [Fe(CN)6]3−/[Fe(CN)6]4− redox system increases with increasing surface roughness. The apparent increase in the reversibility of the reaction may be also explained by the decrease in the true current density. Although the variations in the electrochemical parameters are not strongly pronounced, the tendencies observed can be used to optimise the electrode properties. 相似文献
19.
Sridhar Komarneni Bharat L. Newalkar Dongsheng Li Tarun Gheyi Christina L. Lopano Peter J. Heaney Jeffrey E. Post 《Journal of Porous Materials》2003,10(4):243-248
Several nitrate containing anionic clays were synthesized at different temperatures and the kinetics of NO3
– release were determined to test their suitability as slow-release N fertilizers. A sample (Mg:Al = 2:1) synthesized at 60°C with smaller particle size released 75, 86 and 100% of its NO3
– in 1, 3 and 7 days, respectively when equilibrated with a simulated soil solution. On the other hand, the 175°C/2 hrs sample with larger particle size released 65, 77 and 84% of its nitrate in 1, 3 and 7 days, respectively. Another anionic clay (synthesized at 175°C/24 hrs) of higher charge density (Mg:Al = 2:1) containing NO3
– was equilibrated with a 0.012 N NaCl or Na2CO3 to test the role of different anions in releasing the NO3
– anion from the interlayers. The results showed that Cl– released more NO3
– than did CO3
2– from this anionic clay after all the treatment times probably as a result of the CO3
2– anion blocking the release of NO3
– from the interior of the crystals. When a lower charge density (Mg:Al = 3:1) sample (synthesized at 175°C/48 hrs) was equilibrated with 0.02N solution of anions the release of nitrate was as follows: Cl– < F– < SO4
= CO3
2–. These results suggest that the divalent SO4
= and CO3
2– anions are more effective in the release of NO3
– from this lower charge density anionic clay. Time-resolved structural analysis of NO3
– exchange with CO3
2– in the above anionic clay using synchrotron x-ray diffraction showed that ion exchange is rapid because of small crystal size and lower charge density. Thus the release of NO3
– from anionic clays is an interplay among the type of anions present in soil solution, their concentration, pH of soil solution, the charge density and crystal size of anionic clay etc. 相似文献
20.
Titanium dioxide (TiO2) films on glassy carbon (GC) electrode surface were prepared by the liquid phase deposition (LPD) process for different deposition
times. The morphological structure, interfacial property and electrocatalytic activity of as-prepared LPD TiO2 films on GC surface were studied by field-emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS). The FE-SEM observation showed that the deposition time controlled the morphology of film on
GC surface. With increasing deposition time, TiO2 formed nanoparticles at the initial 5-h stage and compact thick films after 20 h. Due to the semiconducting properties of
TiO2, the LPD films inhibited the electron transfer process of [Fe(CN)6]3−/[Fe(CN)6]4− on GC by increasing the redox reaction peak potential separation of CV curve and electron transfer resistance of EIS. The
inhibition was increased with TiO2 film thickness. Nevertheless, the onset reduction potential of maleic acid decreased with increasing LPD TiO2 film thickness while the cathodic and anodic currents increased, demonstrating the useful electrocatalytic activity of LPD
TiO2 films. 相似文献