共查询到20条相似文献,搜索用时 31 毫秒
1.
Xiaohu Qu Ayman Nafady Adam Mechler Jie Zhang Alexander R. Harris Anthony P. O’Mullane Lisandra L. Martin Alan M. Bond 《Journal of Solid State Electrochemistry》2008,12(6):739-746
In situ atomic force microscopy (AFM) allows images from the upper face and sides of TCNQ crystals to be monitored during
the course of the electrochemical solid–solid state conversion of 50 × 50 μm2 three-dimensional drop cast crystals of TCNQ to CuTCNQ or M[TCNQ]2(H2O)2 (M = Co, Ni). Ex situ images obtained by scanning electron microscopy (SEM) also allow the bottom face of the TCNQ crystals,
in contact with the indium tin oxide or gold electrode surface and aqueous metal electrolyte solution, to be examined. Results
show that by carefully controlling the reaction conditions, nearly mono-dispersed, rod-like phase I CuTCNQ or M[TCNQ]2(H2O)2 can be achieved on all faces. However, CuTCNQ has two different phases, and the transformation of rod-like phase 1 to rhombic-like
phase 2 achieved under conditions of cyclic voltammetry was monitored in situ by AFM. The similarity of in situ AFM results
with ex situ SEM studies accomplished previously implies that the morphology of the samples remains unchanged when the solvent
environment is removed. In the process of crystal transformation, the triple phase solid∣electrode∣electrolyte junction is
confirmed to be the initial nucleation site. Raman spectra and AFM images suggest that 100% interconversion is not always
achieved, even after extended electrolysis of large 50 × 50 μm2 TCNQ crystals. 相似文献
2.
A novel type of glassy carbon electrode modified with magnetic carbon-coated nickel nanoparticles (C-Ni/GCE) was fabricated
and the electrochemical properties of brucine were studied using it. The carbon-coated nickel nanoparticles showed excellent
electrocatalytic activity for the redox of brucine and an enhanced electron transfer rate. The electrochemical behavior of
brucine on the C-Ni/GCE was explored by cyclic voltammetry (CV), and a redox mechanism for brucine was proposed. A series
of electrochemical parameters were calculated for brucine by CV and controlled-potential electrolysis. The C-Ni/GCE showed
good sensitivity, selectivity and stability, and was applied to determine the concentration of brucine. The differential pulse
voltammetry (DPV) response of the C-Ni/GCE showed that the catalytic current was linear with the concentration of brucine
in the range of 4.7 × 10−8 to 2.4 × 10−4 mol l−1, with a correlation coefficient of 0.998. The detection limit was 1.4 × 10−8 mol l−1. 相似文献
3.
G. Horányi 《Journal of Solid State Electrochemistry》2000,4(3):153-158
The specific adsorption of anions (HSO4
−, Cl−) present in low concentration (c < 10−3 mol dm−3) was studied by radiotracer techniques in the course of the reduction of dichromate (chromate) species in 1 mol dm−3 HClO4 supporting electrolyte. In accordance with the results of preliminary studies reported earlier, enhancement of the anion
adsorption was found, induced by some adsorbed intermediates of the reduction process. Potential dependence of the induced
adsorption and its correlation with the reduction rate was investigated. The role of adsorption competition between various
anions is discussed. It is concluded that study of the induced anion adsorption could be a tool for the investigation of the
sorption of intermediates formed in the course of the reduction.
Received: 3 May 1999 / Accepted: 10 June 1999 相似文献
4.
Carboxyl group-functionalized single-walled carbon nanotubes (SWNTs) and 2,6-pyridinedicarboxylic acid (PDC) were electropolymerized
by cyclic voltammetry on a glassy-carbon electrode (GCE) surface to form composite films (SWNTs/PDC). Zirconia was then electrodeposited
on the SWNTs/PDC/GCE from an aqueous electrolyte containing ZrOCl2 and KCl by cycling the potential between −1.1 V and +0.7 V at a scan rate of 20 mV s−1. DNA probes with a phosphate group at the 5′ end were easily immobilized on the zirconia thin films, because of the strong
affinity between zirconia and phosphate groups. The sensors were characterized by cyclic voltammetry (CV) and electrochemical
impedance spectroscopy (EIS). EIS was used for label-free detection of the target DNA by measuring the increase of the electron
transfer resistance (R
et) of the electrode surface after the hybridization of the probe DNA with the target DNA. The PAT gene fragment and polymerase
chain reaction (PCR) amplification of the NOS gene from transgenically modified beans were satisfactorily detected by use
of this DNA electrochemical sensor. The dynamic range of detection of the sensor for the PAT gene fragment was from 1.0 × 10−11 to 1.0 × 10−6 mol L−1 and the detection limit was 1.38 × 10−12 mol L−1. 相似文献
5.
Functionalized polypyrrole films were prepared by incorporation of Fe(CN)6
3− as doping anion during the electropolymerization of pyrrole at a glassy carbon electrode from aqueous solution. The electrochemical
behavior of the Fe(CN)6
3−/Fe(CN)6
4− redox couple in polypyrrole was studied by cyclic voltammetry. An obvious surface redox reaction was observed and dependence
of this reaction on the solution pH was illustrated. The electrocatalytic ability of polypyrrole film with ferrocyanide incorporated
was demonstrated by oxidation of ascorbic acid at the optimized pH of 4 in a glycine buffer. The catalytic effect for mediated
oxidation of ascorbic acid was 300 mV and the bimolecular rate constant determined for surface coverage of 4.5 × 10−8 M cm−2 using rotating disk electrode voltammetry was 86 M−1 s−1. Furthermore, the catalytic oxidation current was linearly dependent on ascorbic acid concentration in the range 5 × 10−4–1.6 × 10−2 M with a correlation coefficient of 0.996. The plot of i
p versus v
1/2 confirms the diffusion nature of the peak current i
p.
Received: 12 April 1999 / Accepted: 25 May 1999 相似文献
6.
A voltammetric sensor for the determination of parathion has been developed based on the use of a poly(carmine) film electrode.
The reduction of parathion at the poly(carmine) modified glassy carbon electrode (GCE) is studied by cyclic voltammetry (CV)
and linear scan voltammetry (LSV). Parathion yields a well-defined reduction peak at a potential of −0.595 V on the poly(carmine)
modified GCE in pH 6.0 phosphate buffer solution (PBS). Compared with that on a bare GCE, the reduction peak current of parathion
is significantly enhanced. All the experimental parameters are optimized for the determination of parathion. The reduction
peak current is linear with the parathion concentration in the range of 5.0 × 10−8 to 1.0 × 10−5 mol L−1, and the detection limit is 1.0 × 10−8 mol L−1. 相似文献
7.
Essadik Abdeljalil Bineta Keita Louis Nadjo Roland Contant 《Journal of Solid State Electrochemistry》2001,5(2):94-106
Two groups of techniques have been devised for the electrodeposition of new electroactive oxide films from [P2Mo18O62]6−. In the first group, two adsorption procedures were used: simple immersion of the electrode in a solution containing 10−4 M [P2Mo18O62]6− in a pH 3.50 medium or cycling of the electrode in this solution in the potential domain of the first three two-electron
waves of the heteropolyanion results in surfaces which retain the oxometalate by mere adsorption. Strikingly, during the cycling,
it was found that a fourth wave appears in the potential domain of the first three two-electron waves of [P2Mo18O62]6−, indicating an evolution of the heteropolyanion in the solution. Such an evolution was also observed with aged solutions.
Then, the potential program for the actual modification step was run by cycling either of these electrodes from −0.2 V to
−0.87 V vs. SCE in pure supporting electrolyte. Analysis of the STM images of the surfaces show essentially monomers 1.2–1.5 nm
in diameter just after adsorption and a sizeable increase of the dimensions of the patterns after modification. The predominant
sizes of these aggregates after modification remain in the range 10–12 nm. The second group of techniques consists in a modification
of the electrode surface directly in the solution containing the heteropolyanion. A fixed potential as well as cycling prove
efficient. Thick films are obtained readily, which are better imaged by tapping mode AFM. An increase of the pH to 4.50, in
appropriate conditions, seems to be favourable to the deposition kinetics. The aggregates in the topmost layers are up to
40 nm in diameter and are assembled in interconnected islands. As a whole, these two groups of techniques appear to exert
an important influence on the aggregate sizes. The paper demonstrates that these sizes might be relatively well controlled
by the choice of experimental conditions.
Received: 4 January 2000 / Accepted: 15 February 2000 相似文献
8.
Genovaitė Valiulienė Albina Žielienė Birutė Šimkūnaitė Leonas Naruškevičius Loreta Tamašauskaitė Tamašiūnaitė Vidas Pakštas Algis Selskis 《Journal of Solid State Electrochemistry》2010,14(2):203-212
The electrochemical behavior of Bi2S3 coatings in Watts nickel plating electrolyte was investigated using the cyclic voltammetry, electrochemical quartz crystal
microbalance, X-ray diffraction, and energy dispersive X-ray analysis methods. During the bismuth sulfide coating reduction
in Watts background electrolyte in the potential region from −0.4 to −0.6 V, the Bi2S3 and Bi(III) oxygen compounds are reduced to metallic Bi, and the decrease in coating mass is related to the transfer of S2− ions from the electrode surface. When the bismuth sulfide coating is reduced in Watts nickel plating electrolyte, the observed
increase in coating mass in the potential region −0.1 to −0.4 V is conditioned by Ni2+ ions reduction before the bulk deposition of Ni, initiated by Bi2S3. In this potential region, the reduction of Bi(III) oxygen compounds can occur. After the treatment of as-deposited bismuth
sulfide coating in nickel plating electrolyte at E = −0.3 V, the sheet resistance of the layer decreases from 1013 to 500–700 Ω cm. A metal-rich mixed sulfide Ni3Bi2S2–parkerite is obtained when as-deposited bismuth sulfide coating is treated in Watts nickel plating electrolyte at a potential
close to the equilibrium potential of the Ni/Ni2+ system and then annealed at temperatures higher than 120 °C. 相似文献
9.
Fosamprenavir is a pro-drug of the antiretroviral protease inhibitor amprenavir and is oxidizable at solid electrodes. The
anodic oxidation behavior of fosamprenavir was investigated using cyclic and linear sweep voltammetry at boron-doped diamond
and glassy carbon electrodes. In cyclic voltammetry, depending on pH values, fosamprenavir showed one sharp irreversible oxidation
peak or wave depending on the working electrode. The mechanism of the oxidation process was discussed. The voltammetric study
of some model compounds allowed elucidation of the possible oxidation mechanism of fosamprenavir. The aim of this study was
to determine fosamprenavir levels in pharmaceutical formulations and biological samples by means of electrochemical methods.
Using the sharp oxidation response, two voltammetric methods were described for the determination of fosamprenavir by differential
pulse and square-wave voltammetry at the boron-doped diamond and glassy carbon electrodes. These two voltammetric techniques
are 0.1 M H2SO4 and phosphate buffer at pH 2.0 which allow quantitation over a 4 × 10−6 to 8 × 10−5 M range using boron-doped diamond and a 1 × 10−5 to 1 × 10−4 M range using glassy carbon electrodes, respectively, in supporting electrolyte. All necessary validation parameters were
investigated and calculated. These methods were successfully applied for the analysis of fosamprenavir pharmaceutical dosage
forms, human serum and urine samples. The standard addition method was used in biological media using boron-doped diamond
electrode. No electroactive interferences from the tablet excipients or endogenous substances from biological material were
found. The results were statistically compared with those obtained through an established HPLC-UV technique; no significant
differences were found between the voltammetric and HPLC methods. 相似文献
10.
Single-wall carbon nano-tubes were used to modify the surface of a glassy carbon electrode (GC) and applied in the determination
of folic acid with voltammetry. The experiments demonstrated that the presence of a carbon nano-tube film on the electrode
greatly increased the reduction peak current of folic acid. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were
used in a comparative investigation of the electrochemical reduction of folic acid with the film electrode. Effects of pH
on the peak current and the peak potential were studied in the pH range of 4.0–8.0 with Britton-Robinson buffer solution.
The reduction peak current was found to be linearly related to folic acid concentration over the range of 1 × 10−8 to 1 × 10−4 mol L−1 with a detection limit of 1 × 10−9 mol L−1 after 5 min accumulation. The film electrode provides an efficient way for eliminating interferences from some inorganic
and organic species in the solution. The high sensitivity, selectivity and stability of the film electrode demonstrate its
practical application from a simple and rapid determination of folic acid in tablets. 相似文献
11.
Sayed Medhi Ghoreishi Mohsen Behpour Mohammad Hassan Motaghedi Fard 《Journal of Solid State Electrochemistry》2012,16(1):179-189
In this work, we investigate the electrochemical activity of dopamine (DA) and uric acid (UA) using both a bare and a modified
carbon paste electrode as the working electrode, with a platinum wire as the counter electrode and a silver/silver chloride
(Ag/AgCl) as the reference electrode. The modified carbon paste electrode consists of multi-walled carbon nanotubes (>95%)
treated with α-cyclodextrine, resulting in an electrode that exhibits a significant catalytic effect toward the electro-chemical
oxidation of DA in a 0.2-M Britton–Robinson buffer solution (pH 5.0). The peak current increases linearly with the DA concentration
within the molar concentration ranges of 2.0 × 10−6 to 5.0 × 10−5 M and 5.0 × 10−5 to 1.9 × 10−4 M. The detection limit (signal to noise >3) for DA was found to be 1.34 × 10−7 M, respectively. In this work, voltammetric methods such as cyclic voltammetry, chronoamperometry, chronocuolometry, differential
pulse and square wave voltammetry, and linear sweep and hydrodynamic voltammetry were used. Cyclic voltammetry was used to
investigate the redox properties of the modified electrode at various scan rates. The diffusion coefficient (D, cm2 s−1 = 3.05 × 10−5) and the kinetic parameters such as the electron transfer coefficient (α = 0.51) and the rate constant (k, cm3 mol−1 s−1 = 1.8 × 103) for DA were determined using electrochemical approaches. By using differential pulse voltammetry for simultaneous measurements,
we obtained two peaks for DA and UA in the same solution, with the peak separation approximately 136 mV. The average recovery
was measured at 102.45% for DA injection. 相似文献
12.
V. N. Kiryushov L. I. Skvortsova T. P. Aleksandrova 《Journal of Analytical Chemistry》2011,66(5):510-514
Cyclic and direct voltammetry with linear potential sweep has been used for the investigation of the dependence of the reversibility
and reduction current in the system Fe(CN)63−/Fe(CN)64− on the concentrations of LiCl, NaCl, KCl, and CsCl solutions. The electrode was made of a graphite-epoxy composite and activated
by mechanically cutting a surface layer directly in the solution and deactivated by the long-term storage in the air. The
selected type of the graphite electrode and the method used to activate its surface provides the reversibility and diffusion
control of the electrode process in the system Fe(CN)63−/Fe(CN)64− regardless of the composition of the supporting solution. In the case of the deactivated electrode, the degree of irreversibility
of this process depends on the form and concentration of metal chloride in the supporting electrolyte and the diffusion transfer
is complicated by the adsorption of compounds formed between the ferricyanide and the cation of the supporting solution. 相似文献
13.
Krzysztof Miecznikowski James A. Cox Adam Lewera Pawel J. Kulesza 《Journal of Solid State Electrochemistry》2000,4(4):199-204
We describe a sol-gel approach by which iron hexacyanoferrate is immobilized in silica in a manner suited to investigation
by electrochemistry in the absence of a contacting liquid phase. Such physicochemical parameters as concentration of redox
sites (C
o) and apparent (effective) diffusion coefficient (D
app) are estimated by performing cyclic voltammetric and potential step experiments in two time regimes, which are characterized
by linear and spherical diffusional patterns, respectively. Values of D
app and C
o thereby obtained are 2.0 × 10−6 cm2 s−1 and 1.4 × 10−2 mol dm−3. The D
app value is larger than expected for a typical solid redox-conducting material. Analogous measurements done in iron(III) hexacyanoferrate(III)
solutions of comparable concentrations, 1.0 × 10−2 and 5.0 × 10−3 mol dm−3, yield D
app on the level of 5–6 × 10−6 cm2 s−1. Thus, the dynamics of charge propagation in this sol-gel material is almost as high as in the liquid phase. The residual
water in the silica, along with the pore structure, are important to the overall mechanism of charge transport, which apparently
is limited by physical diffusion rather than electron self-exchange. Under conditions of a solid state voltammetric experiment
which utilizes an ultramicroelectrode, encapsulated iron hexacyanoferrate redox centers seem to be in the dispersed colloidal
state rather than in a form of the rigid polymeric film.
Received: 8 April 1999 / Accepted: 13 August 1999 相似文献
14.
A self-assembled electrode with a meso-2,3-dimercaptosuccinic acid (DMSA) monolayer has been characterized by electrochemical
quartz crystal microbalance and complex impedance analysis, surface enhanced Raman spectroscopy and cyclic voltammetry. The
self-assembled electrode was used for the simultaneous electrochemical detection of epinephrine (EP) and uric acid (UA) in
phosphate buffer of pH 7.7. The simultaneous oxidation of EP and UA was performed by cyclic voltammetry (CV) and differential
pulse voltammetry (DPV), and the signals for each method were well separated with a potential difference of over 330 mV and
without interference by each other. The detection limit of EP is 5.4 × 10−8 mol L−1 by CV and 5.3 × 10−8 mol L−1 by DPV and that of UA is 8.4 × 10−8 mol L−1 by CV and 4.2 × 10−8 mol L−1 by DPV. The DMSA self-assembled electrode can be applied to the simultaneous determination of EP and UA. 相似文献
15.
A new modified electrode was prepared by electrodeposition of caffeic acid (CFA) at the surface of an activated glassy carbon
electrode. Cyclic voltammetry was used to investigate the redox properties of this electrode at various solution pH values
and at various scan rates. The pH dependence of the electrode response was found to be 58.5 mV/pH, which is very close to
the expected Nernstian value. The electrode was also employed to study electrocatalytic oxidation of reduced nicotinamide
adenine dinucleotide (NADH), using cyclic voltammetry, chronoamperometry and rotating disk voltammetry as diagnostic techniques.
It was found that the modified electrode exhibits potent and persistent electrocatalytic properties toward NADH oxidation
in phosphate buffer solution (pH 7.0) with a diminution of the overpotential of about 450 mV compared to the process at an
unmodified electrode. The electrocatalytic current increases linearly with NADH concentration in the range tested from 0.05
to 1.0 mM. The apparent charge transfer rate constant and transfer coefficient for electron transfer between the electrode
surface and immobilized CFA were calculated as 11.2 s−1 and 0.43, respectively. The heterogeneous rate constant for oxidation of NADH at the CFA-modified electrode surface was also
determined and found to be about 3 × 103 M−1 s−1. Finally, the diffusion coefficient of NADH was calculated as 3.24 × 10−6 cm2 s−1 for the experimental conditions, using chronoamperometric results.
Received: 6 January 1999 / Accepted: 11 May 1999 相似文献
16.
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
17.
Marcin Opallo 《Journal of Solid State Electrochemistry》1998,2(5):347-354
The electrochemical redox reactions: Fe(CN)6
4−−e−↔ Fe(CN)6
3−, Ru(NH3)6
3++e−↔ Ru (NH3)6
2+ and Fc(CH2OH)2−e−↔ Fc(CH2OH)2
+ (Fc–ferrocene) were investigated in tetrabutylammonium halide hydrates at temperatures below and above the electrolyte melting
point. They were studied by cyclic voltammetry, potential step chronoamperometry and impedance spectroscopy. Freezing of
the electrolyte affects both the shape and position of the cyclic voltammogram on the potential scale. Also the shapes of
the current-time relationship and the impedance spectra change at temperatures below the melting point. It has been proposed
that this behaviour is caused by slow transport of the reactant and the heterogeneous nature of the electrolyte. The activation
energies of reactant transport are about four times larger in frozen electrolytes than those in liquid. It has been concluded
that reactant transport is restricted to the intergrain space of the electrolyte.
Received: 16 December 1997 / Accepted: 10 February 1998 相似文献
18.
Pandey G. P. Agrawal R. C. Hashmi S. A. 《Journal of Solid State Electrochemistry》2011,15(10):2253-2264
Effect of fumed silica dispersion on poly(vinylidene fluoride-co-hexafluoropropylene)-based magnesium ion-conducting gel polymer
electrolyte has been studied using various physical and electrochemical techniques. The composite gel electrolytes are free-standing
and flexible films with enough mechanical strength. The optimized composition with 3 wt.% filler offers a maximum ionic conductivity
of ∼1.1 × 10−2 S cm−1 at ∼25 °C with good thermal and electrochemical stabilities. The Mg2+ ion conduction in the gel nanocomposite film is confirmed from the cyclic voltammetry, impedance spectroscopy, and transport
number measurements. The space-charge layers formed between filler particles and gel electrolyte are responsible for the enhancement
in ionic conductivity. The applicability of the gel nanocomposite to a rechargeable battery is examined by fabricating a prototype
cell consisting of Mg [or Mg-multiwalled carbon nanotube (MWCNT) composite] and MoO3 as negative and positive electrodes, respectively. The discharge capacity and the rechargeability of the cell have been improved
when Mg metal is substituted by Mg-MWCNT composite. The discharge capacity of the optimized cell has found to be ∼175 mAh g−1 of MoO3 for an initial ten charge–discharge cycles. 相似文献
19.
The fabrication and electrochemical characteristics of a penicillamine (PCA) self-assembled monolayer modified gold electrode
were investigated. The electrode can enhance the electrochemical response of uric acid (UA), and the electrochemical reaction
of UA on the PCA electrode has been studied by cyclic voltammetry and differential pulse voltammetry. Some electrochemical
parameters, such as diffusion coefficient, standard rate constant, electron transfer coefficient and proton transfer number
have been determined for the electrochemical behavior on the PCA self-assembled monolayer electrode. The electrode reaction
of UA is an irreversible process, which is controlled by the diffusion of UA with two electrons and two protons transfer at
the PCA/Au electrode. In phosphate buffer (pH 5.0), the peak current is proportional to the concentration of UA in the range
of 6.0 × 10−5–7.0 × 10−4 mol L−1 and 2.0 × 10−5–7.0 × 10−4 mol L−1 for the cyclic voltammetry and differential pulse voltammetry methods with the detection limits of 5.0 × 10−6 and 3.0 × 10−6 mol L−1, respectively. The method can be applied to determine UA concentration in real samples. 相似文献
20.
A novel electrochemical sensor for methyl parathion based on silicate– cetyltrimethylammonium bromide nanocomposite film has
been fabricated by electro-assisted deposition onto glassy carbon electrode in one-step via an electrochemical modulation
of pH at the electrode/solution interface to promote controlled gelification of tetraethylorthosilicate sol, and was characterized
with scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The electrochemical sensing
of methyl parathion on the film-modified electrode was investigated applying cyclic voltammetry and square wave voltammetry.
Compared to the unmodified electrode, the shapes of the redox peaks were improved and the peak currents significantly increased.
Experimental parameters such as deposition time, pH value, and accumulation conditions have been optimized. A linear relationship
between the peak current and methyl parathion concentration was obtained in the range from 1.0 × 10−7 to 1.0 × 10−4 mol L−1 with a detection limit of 1.04 × 10 −8 mol L−1 (S/N = 3) after accumulation at 0 V for 120 s. The film electrode shows great promise for determination of methyl parathion in
real samples.
相似文献