共查询到20条相似文献,搜索用时 15 毫秒
1.
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
2.
Jesús López-Palacios Aránzazu Heras Álvaro Colina Virginia Ruiz 《Electrochimica acta》2004,49(7):1027-1033
Electrogeneration of soluble Prussian Blue (PB) during the oxidation-reduction of the Fe(CN)63−/Fe(CN)64− system has been detected using bidimensional spectroelectrochemistry (BSEC). This new technique allows us to obtain simultaneously two different spectroscopic signals together with an electrochemical signal, each one containing different information. Starting from pure Fe(CN)64− solutions, some experimental conditions under which soluble PB appears, have been analysed. Fe(CN)64−/supporting electrolyte concentration ratio and potential scan rate have been found as the most influential factors. All experiments show clearly the generation of soluble PB but in no case the insoluble form has been detected. From the results, PB generation can be explained as a surface chemical process coupled with the electron transfer reaction. 相似文献
3.
Seongpil Hwang Bang Sook Lee Young Shik Chi Insung S. Choi 《Electrochimica acta》2008,53(5):2630-2636
In this work, we studied interfacial proton transfer of the self-assembled monolayer (SAM) of 1-(12-mercaptododecyl)imidazole on a gold electrode by faradaic impedance titration method with Fe(CN)63− as an anionic redox probe molecule. The surface pK1/2 was found to be 7.3, which was nearly the same as that of 1-alkylimidazole in solution. We also investigated the electrochemical properties of the SAM-modified electrode by cyclic voltammetry. Cyclic voltammetry was performed (1) in the solution containing Fe(CN)63− with repeated alternation of pH values to investigate the electrostatic interaction of the protonated or deprotonated imidazole with Fe(CN)63− and (2) in the acidic or basic electrolyte containing Ru(NH3)63+ as a cationic redox probe to verify the effect of the polarity of a redox probe. We observed the reversible adsorption/desorption of Fe(CN)63− and concluded that the adsorbed Fe(CN)63− catalyzed the electron transfer of both Fe(CN)63− itself and cationic Ru(NH3)63+. 相似文献
4.
We propose a novel composite (hybrid) organic/inorganic system that can be prepared as a coating (on 1 μm level) on glassy carbon and metal electrode substrates. Poly(3,4-ethylenedioxythiophene) or PEDOT based composite coatings were electrodeposited using cyclic voltammetry on glassy carbon and stainless steel substrates in the presence of 4-(pyrrole-1-yl) benzoic acid (PyBA) and phosphododecamolybdic acid (PMo12). The coating growth was facilitated by the addition of polyoxyethylene-10-laurylether (BRIJ10) neutral surfactant at the level of 0.04 mol dm−1 to improve solubility of the 3,4-ethylenedioxythiophene monomer and to form an aqueous micellear solution in the reaction medium. The fact that carboxylate-containing PyBA units link positively charged PEDOT structures tends to improve overall stability and adherence of composite coatings to stainless steel. The PEDOT/PyBA composite serves as a stable host matrix for large negatively charged polymolybdate inorganic species. Consequently, due to the formation of denser polymeric structures and to the existence of electrostatic repulsion effects, the polyanion-containing composite coatings are capable of largely blocking the access of pitting-causing anions (chlorides) to the surface of stainless steel. Interaction of phosphomolybdate with metal ions, namely with chromium(III) or even iron(III) or iron(II) that exist at the stainless steel–composite coating interface, may lead to the formation of insoluble deposits and exhibit overall passivating effect. 相似文献
5.
The effects of pH and of the nature and concentration of the electrolyte on the electrochemical behaviour of the Fe(CN)3–/4–
6 charge-transfer reaction at a poly(2-vinylpyridine)-coated electrode formed by electropolymerization have been studied. Cyclic voltammetry during the Fe(CN)3–
6 incorporation process was combined with measurement of the saturated concentration of the Fe(CN)3–
6 confined in the films to investigate the electrochemical behaviour and the fundamental nature of the ion-exchange polymers. The poly(2-vinylpyridine) films formed by electropolymerization were found to have better properties (i.e., larger amount of Fe(CN)3–
6 can be incorporated at various pH values and films are more chemically stable under acidic conditions) as polymer-modified electrodes than those formed by solvent evaporation. Of the various anions studied, ClO–
4 was found to be distinct from the others (Cl–, NO–
3, Br– and SO2–
4). On the one hand, the polymer films exposed to ClO–
4 are more dense and rigid than those exposed to other anions and show relatively little electroactivity. On the other hand, when the films are exposed to increasing concentrations of Cl–, the films become more swollen, thereby reducing the resistance within the film and enhancing the rate of charge-transfer from the outer film surface to the electrode surface. 相似文献
6.
Pawel J. Kulesza Magdalena Skunik Krzysztof Miecznikowski Katarzyna Karnicka François Béguin Marie-Helene Delville Andrzej Ernst 《Electrochimica acta》2006,51(11):2373-2379
The ability of a Keggin-type polyoxometallate, phosphododecamolybdate (PMo12O403−), to form stable anionic monolayers on carbon nanoparticles and multi-wall nanotubes is explored here to produce stable colloidal solutions of polyoxometallate covered carbon nanostructures and to disperse them within conducting polymer, poly(3,4-ethylenedioxythiophene), i.e. PEDOT, or polyaniline multilayer films. By repeated alternate treatments in the colloidal suspension of PMo12O403−-protected carbon nanoparticles or nanotubes, and in the acid solution of a monomer (3,4-ethylenedioxythiophene or aniline), the amount of the material can be increased systematically (layer-by-layer) to form stable three-dimensional organized arrangements (networks) of interconnected organic and inorganic layers on electrode (e.g. glassy carbon) surfaces. In hybrid films, the negatively charged polyoxometallate-covered carbon nanostructures interact electrostatically with positively charged conducting polymer ultra-thin layers. Consequently, the attractive electrochemical charging properties of conducting polymers, reversible redox behavior of polyoxometallate, as well as the mechanical and electrical properties of carbon nanoparticles or nanotubes can be combined. The films are characterized by fast dynamics of charge transport, and they are of potential importance to electrocatalysis and charge storage in redox capacitors. 相似文献
7.
Isaac Adebayo Akinbulu 《Electrochimica acta》2010,55(23):7085-7093
Self-assembled monolayer (SAM) films of iron (SAM-1), cobalt (SAM-2) and manganese (SAM-3) phthalocyanine complexes, tetra-substituted with diethylaminoethanethio at the non-peripheral positions, were formed on gold electrode in dimethylformamide (DMF). Electrochemical, impedimentary and surface properties of the SAM films were investigated. Cyclic voltammetry was used to investigate the electrochemical properties of the films. Ability of the films to inhibit common faradaic processes on bare gold surface (gold oxidation, solution redox chemistry of [Fe(H2O)6]3+/[Fe(H2O)6]2+ and underpotential deposition (UDP) of copper) was investigated. Electrochemical impedance spectroscopy (EIS), using [Fe(CN)6]3−/4− redox process as a probe, offered insights into the electrical properties of the films/electrode interfaces. Surface properties of the films were probed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The films were employed for the electrocatalytic oxidation of the pesticide, carbofuran. Electrocatalysis was evidenced from enhanced current signal and less positive oxidation potential of the pesticide on each film, relative to that observed on the bare gold electrode. Mechanism of electrocatalytic oxidation of the pesticide was studied using rotating disc electrode voltammetry. 相似文献
8.
K4Fe(CN)6 was used to improve the microstructure and properties of copper deposits obtained from hypophosphite baths. In electroless
copper plating solutions using hypophosphite as the reducing agent, nickel ions (0.0038 M with Ni2+/Cu2+ mole ratio 0.12) was used to catalyze hypophosphite oxidation. However, the color of the copper deposits was dark or brown
and its resistivity was much higher than that obtained in formaldehyde baths. The effects of K4Fe(CN)6 on the deposit composition, resistivity, structure, morphology and the electrochemical reactions of hypophosphite (oxidation)
and cupric ion (reduction) have been investigated. The deposition rate and the resistivity of the copper deposits decreased
significantly with the addition of K4Fe(CN)6 to the plating solution and the color of the deposits changed from dark-brown to copper-bright with improved uniformity.
The nickel and phosphorus content in the deposits also decreased slightly with the use of K4Fe(CN)6. Smaller crystallite size and higher (111) plane orientation were obtained by addition of K4Fe(CN)6. The electrochemical current–voltage results show that K4Fe(CN)6 inhibited the catalytic oxidation of hypophosphite at active nickel sites and reduced the reduction reaction of cupric ions
on the deposit surface by adsorption on the electrode. This results in lower deposition rate and a decrease in the mole ratio
of NaH2PO2/CuSO4 consumed during plating. 相似文献
9.
The organic–inorganic material consisted of poly(3,4-ethylenedioxythiophene) (pEDOT) and copper hexacyanoferrate (Cuhcf) was synthesized. The pEDOT film with Fe(CN)63−/4− as counter-ions potentiodynamically polarized in aqueous CuCl2 electrolyte brings about stable hybrid material (pEDOT/Cuhcf) performing single redox activity of FeII/III at a formal potential Ef = 0.61 V (vs. Ag/AgCl/0.1 M KCl) and less clearly shaped two redox coming from copper ions entrapped inside the film. XPS ex situ measurements show three different binding energies for copper (Cu 2p3/2: 932.2, 934.8 and 936.3 eV) and two for iron (Fe 2p3/2: 708.2 and 709.0 eV). Spectroelectrochemical measurements allowed to establish an order in the energy band gap (Eg) for the investigated hybrids pEDOT/Mehcf (Me = Fe, Co, Ni, Cu) as follows: Eg(pEDOT/Fehcf) = 1.40 eV < Eg(pEDOT/Cohcf) = 1.48 eV < Eg(pEDOT/Nihcf) = 1.52 eV < Eg(pEDOT/Cuhcf) = 1.6 eV. The hybrid materials were examined as electrodes for electrocatalytic reduction of H2O2. Copper centres in pEDOT/Cuhcf as well as high spin iron centres in pEDOT/Fehcf were found to be electrocatalytically active towards hydrogen peroxide reduction. 相似文献
10.
The surface of two natural smectite-type clay samples was chemically modified by covalent grafting of amine groups, by reaction with γ-aminopropyltriethoxysilane, which were easily protonated in HCl medium. Multisweep cyclic voltammograms of clay-film modified glassy carbon electrodes made of either the raw clays or the propylammonium-functionalized samples exposed to Ru(NH3)63+ or Fe(CN)63− electroactive probes were obtained. The results indicated a permselective behavior of these clay and organoclay-films based on either favorable or unfavorable electrostatic interactions. The cation-exchanging raw clay film modified electrodes exhibited accumulation properties for Ru(NH3)63+ species while rejecting Fe(CN)63−, whereas the anion-exchanging organoclay coatings acted as a barrier against Ru(NH3)63+ while increasing dramatically the concentration of Fe(CN)63− species at the electrode surface. Strong binding of the probe to the organoclays resulted in a potential shift of ca. 0.1 V of the voltammetric signals characteristic of the Fe(CN)63−/4− couple in the anodic direction. Their good preconcentration efficiency at low analyte concentration highlighted their interest for electroanalytical applications. 相似文献
11.
Sulfonated thiophenes, sodium 2-(3-thienyloxy)ethanesulfonate (C6H7S2O4Na) and sodium 6-(3-thienyloxy)hexanesulfonate (C10H15S2O4Na), were synthesized and used in the fabrication of ion-selective electrodes (ISEs) sensitive and selective to Ag+. The Ag+-ISEs were prepared by galvanostatic electropolymerization of 3,4-ethylenedioxythiophene (EDOT) on glassy carbon (GC) electrodes, with either C6H7S2O4− or C10H15S2O4− as the charge compensator (doping ion) for p-doped poly(3,4-ethylenedioxythiophene) (PEDOT). Potentiometric measurements were carried out with these sensors, GC/PEDOT(C6H7S2O4−) and GC/PEDOT(C10H15S2O4−), to study and compare their sensitivity and selectivity to silver ions. PEDOT(C6H7S2O4−) and PEDOT(C10H15S2O4−) films were also studied by using other techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), electrochemical quartz crystal microbalance (EQCM) and Fourier transform infrared spectroscopy (FTIR).Results from the potentiometric measurements showed that the difference in length of the alkyl chain of the doping ions C6H7S2O4− and C10H15S2O4− has no significant effect on the sensitivity or selectivity of GC/PEDOT(C6H7S2O4−) and GC/PEDOT(C10H15S2O4−) sensors to Ag+. More differences can be seen in the cyclic voltammograms and EIS spectra of the sensors. FTIR spectra confirmed that both C6H7S2O4− and C10H15S2O4− act as doping ions in the electrosynthesis of PEDOT-based films and they are not irreversibly immobilized in the polymer backbone. 相似文献
12.
This paper describes the electrochemical properties, such as electrode reactivity, and interfacial capacitance of an anthracene/self-assembled monolayer (An/SAM) Au electrode prepared through controllable immersion of the dodecanethiol (C12SH) SAM-Au electrode in a THF solution of anthracene (An). The C12SH SAM almost totally blocks heterogeneous electron transfer between the bare Au electrode and Fe(CN)63−/4− in solution, but adsorption of the An molecules onto the SAM-Au electrode restores electron transfer. The prepared An/SAM-Au electrode possesses good reactivity without a remarkable barrier to heterogeneous electron transfer. On the other hand, the electroactive form of the An/SAM-Au electrode can be converted back to the non-electroactive form by immersing the electrode into pure THF. 相似文献
13.
C. Deslouis J. de SanoitS. Saada C. MerA. Pailleret H. Cachet P. Bergonzo 《Diamond and Related Materials》2011,20(1):1-10
Electrochemical activity, morphology and surface electrical conductivity of Boron-Doped Polycrystalline Diamond films prepared by MPCVD have been investigated. Heterogeneous apparent rate constants of three different redox systems, [Fe(CN)6]3−/4−, [IrCl6]2−/3− and [Ru(NH3)6]3+/2+ have been measured by both Cyclic Voltammetry and Electrochemical Impedance Spectroscopy on < 100 > textured films with a predominance of (111) faces: first measurements have been done with [Fe(CN)6]3−/4− only on as grown samples, and secondly after a mild electrochemical pretreatment the three redox systems have been investigated. “As-grown” samples showed a moderate average activity which was related to the presence of a minority of electronically conducting areas among insulating zones. Electrochemical treatment in neutral conditions substantially increased the activity and heterogeneous apparent rate constants kapp for the three couples were measured in the range of 10− 2 cm s− 1 with a good stability in time. Current-sensing AFM images performed ex situ showed that the electrochemically pre-treated material presented a high superficial conductivity whereas the grown sample showed major area of low conductivity. 相似文献
14.
Poly(o-aminophenol) (POAP) was formed by successive cyclic voltammetry in monomer solution in the presence of sodium dodecyl sulfate (SDS) on the surface of a carbon paste electrode. The electrochemical behavior of the SDS-POAP carbon paste electrode has been investigated by cyclic voltammetry in 0.5 M HClO4 and 5 mM K4[Fe(CN)6]/0.1 M KCl solutions as the supporting electrolyte and model system, respectively. Ni(II) ions were incorporated into the electrode by immersion of the polymeric modified electrode having amine groups in 0.1 M Ni(II) ion solution. Cyclic voltammetric and chronoamperometric experiments were used for the electrochemical study of this modified electrode. A good redox behavior of the Ni(III)/Ni(II) couple at the surface of electrode can be observed. The electrocatalytic oxidations of methanol and ethylene glycol (EG) at the surface of the Ni/SDS-POAP electrode were studied in a 0.1 M NaOH solution. Compared to bare carbon paste and POAP-modified carbon paste electrodes, the SDS-POAP electrode significantly enhanced the catalytic efficiency of Ni ions for methanol oxidation. Finally, using a chronoamperometric method, the catalytic rate constants (k) for methanol and ethylene glycol were found to be 2.04 × 105 and 1.05 × 107 cm3 mol−1 s−1, respectively. 相似文献
15.
Yoriko Tanaka Masahiro Furuta Koichi Kuriyama Ryosuke Kuwabara Yukiko Katsuki Takeshi Kondo Akira Fujishima Kensuke Honda 《Electrochimica acta》2011,(3):1172
Nitrogen-doped hydrogenated amorphous carbon thin films (a-C:N:H, N-doped DLC) were synthesized with microwave-assisted plasma-enhanced chemical vapor deposition widely used for DLC coating such as the inner surface of PET bottles. The electrochemical properties of N-doped DLC surfaces that can be useful in the application as an electrochemical sensor were investigated. N-doped DLC was easily fabricated using the vapor of nitrogen contained hydrocarbon as carbon and nitrogen source. A N/C ratio of resulting N-doped DLC films was 0.08 and atomic ratio of sp3/sp2-bonded carbons was 25/75. The electrical resistivity and optical gap were 0.695 Ω cm and 0.38 eV, respectively. N-doped DLC thin film was found to be an ideal polarizable electrode material with physical stability and chemical inertness. The film has a wide working potential range over 3 V, low double-layer capacitance, and high resistance to electrochemically induced corrosion in strong acid media, which were the same level as those for boron-doped diamond (BDD). The charge transfer rates for the inorganic redox species, Fe2+/3+ and Fe(CN)64−/3− at N-doped DLC were sufficiently high. The redox reaction of Ce2+/3+ with standard potential higher than H2O/O2 were observed due to the wider potential window. At N-doped DLC, the change of the kinetics of Fe(CN)63−/4− by surface oxidation is different from that at BDD. The rate of Fe(CN)63−/4− was not varied before and after oxidative treatment on N-doped DLC includes sp2 carbons, which indicates high durability of the electrochemical activity against surface oxidation. 相似文献
16.
Wanda M. Aylward 《Electrochimica acta》2008,53(11):3897-3902
The effects of organosulphonate groups on the ion-exchange and ion-transport properties of silica hydrogels have been investigated by using Ru(NH3)63+, Ru(bpy)32+ and Fe(CN)63− redox probes. Silica and sulphonated ormosil hydrogels were prepared by using tetramethyl orthosilicate as a silica precursor and 2(4-chlorosulphonylphenyl)ethyl-trichlorosilane to provide sulphonate functionality for ion-exchange and ion conductivity. Both gels act as cation-exchangers and exclude Fe(CN)63−. Partition coefficients are higher for the ormosil and for the more highly charged Ru(NH3)63+ versus Ru(bpy)32+. Diffusion coefficients are higher for the unmodified silica, which is consistent with weaker interactions between the cationic probes and less anionic gel network. 相似文献
17.
Diana M. Fernandes Mariana E. Ghica Ana M.V. Cavaleiro Christopher M.A. Brett 《Electrochimica acta》2011,(23):7940
Electrochemical impedance spectroscopy (EIS) has been used to study multilayer films containing anionic iron-substituted silicotungstate [SiW11FeIII(H2O)O39]5− (SiW11Fe) and positively charged poly(ethylenimine) self-assembled by the layer-by-layer method on glassy carbon and indium tin oxide electrodes. The effect of the charge of the outermost layer of the multilayer assembly on the electron transfer of soluble species was studied using the redox probes [Fe(CN)6]3− and [Ru(NH3)6]3+; cyclic voltammetry indicating that the surface charge has a significant effect on the process. EIS demonstrated that the electrostatic attraction or repulsion between the surface and the redox probes plays a significant role. Analysis of the impedance spectra showed that the charge transfer resistance increases with an increasing number of bilayers for both redox probes and that the porosity of the multilayer film, which varies with the electrode substrate, also has a significant effect on the electrochemical response. 相似文献
18.
Marcin Ocypa 《Electrochimica acta》2006,51(11):2298-2305
Electrochemical properties of poly(3,4-ethylenedioxythiophene) doped with hexacyanoferrate(II,III) ions (PEDOT(HCF)) were studied in the presence of Cu2+ ions. Voltammetric and EDAX studies revealed retention of hexacyanoferrate anions in the polymer film and accumulation of Cu(II) cations, as well as formation of solid copper hexacyanoferrate near the polymer surface.Accumulation of Cu2+ ions was found to be advantageous from the point of view of PEDOT(HCF) applications as a solid contact (ion-to-electron transducer) in all-solid-state Cu2+-selective electrodes with solvent polymeric polyvinyl chloride (PVC) based membrane, containing Cu2+-selective ionophore. Binding of Cu2+ ions in the conducting polymer layer results in analyte ions flux into the transducer phase. Thus, pronounced enhancement of selectivity of the all-solid-state Cu2+-selective electrode or lower detection limit of the potentiometric response range was achieved, reaching under optimised conditions 10−7 M CuSO4. 相似文献
19.
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
20.
Kenneth I. Ozoemena Tebello Nyokong Duduzile Nkosi Michael J. Cook 《Electrochimica acta》2007,52(12):4132-4143
This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower (∼10 times) electron-transfer resistance (Ret) and much higher (∼10 times) apparent electron-transfer rate constant (kapp) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface. 相似文献