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1.
Nitrogenated nanocrystalline diamond films with controlled electrical conductivity are grown in electrical arc plasma in CH4/H2/Ar/N2 gas mixtures and characterized by scanning electron microscopy and spectroscopic measurements. Their electrochemical properties
are studied by electrochemical impedance spectroscopy. Transfer coefficients of reactions in the [Fe(CN)6]3−/4− redox system are determined. The electrochemical behavior of the material is controlled by its nitrogenation (3–20% N2 in the reaction gas mixture). The nitrogenated nanocrystalline diamond has higher differential capacitance in indifferent
electrolyte (1 M KCl) solution than not nitrogenated one; the nitrogenation also increases the reversibility of reactions
in the [Fe(CN)6]3−/4− redox system. By and large, with nitrogenation of diamond, its electrochemical behavior changes from the one characteristic
of a “poor conductor” to that characteristic of metallike conductor. In this respect the nanocrystalline diamond electrodes
grown in the electrical arc plasma are similar to those grown in microwave plasma. 相似文献
2.
Abolanle S. Adekunle Kenneth I. Ozoemena 《Journal of Solid State Electrochemistry》2008,12(10):1325-1336
Electrochemistry of edge-plane pyrolytic graphite electrodes (EPPGEs) modified with Aldrich single-walled carbon nanotubes
(SWCNTs) electro-decorated with metal (Ni, Fe and Co) and their oxides have been studied. The morphology and identity of the
metallic dispersions were examined by scanning electron microscopy and energy-dispersive spectroscopy. We show that SWCNTs
serve as efficient conducting carbon material for electronic communication between metal films and the underlying carbon electrode.
By using cyclic voltammetry and electrochemical impedance spectroscopy (EIS) techniques, it is proved that both EPPGE-SWCNT-Ni
and EPPGE-SWCNT-Fe exhibit comparable electrochemical response in buffered aqueous solution (pH 7.0) and towards electro-oxidation
of hydrazine in Na2SO4 solution. The impedance spectra of these SWCNT-metal hybrids were complicated and follow electrical equivalent circuit model
typical of adsorption-controlled charge transfer kinetics. Hydrazine impedance spectra exhibited inductive loop, characteristic
of Faradaic current being governed by the occupation of an intermediate state. On the other hand, the EIS data obtained in
a simple redox probe, [Fe(CN)6]3−/[Fe(CN)6]4−, showed that EPPGE-SWCNT and EPPGE-SWCNT-Ni followed electrical equivalent circuit models typical of partial charge transfer
or adsorption-controlled kinetics with some resemblance to the behaviour of electrolyte–insulator–semiconductor sensors. 相似文献
3.
Electrochemical behavior of unitary or binary self-assembled monolayers with thiol-derivatized cobaltous porphyrin 总被引:1,自引:0,他引:1
A new thiol-derivatized metalloporphyrin, 5-{3-methoxyl-4-(4-mercaptobutoxy)}phenyl-10,15,20-triphenylporphyrincobalt (MBPPCo),
has been synthesized. The electrochemical behavior of unitary or binary self-assembled monolayers (SAMs) of MBPPCo and thiols
with carboxylic terminal groups was investigated using Fe(CN)6
3−/4− and ascorbic acid (AA) as probe species. The binary modified electrode showed a small increase in peak current but a large
decrease in overpotential. However, in anionic electroactive species [Fe(CN)6
3−/4− or AA], either positively charged MBPPCo or negatively charged thiol SAMs solely, slow electron transfer kinetics was obtained
and the possible reasons for the discrepancy are discussed. 相似文献
4.
Gold nanoparticles (nano Au)/titanium dioxide (TiO2) hollow microsphere membranes were prepared on the carbon paste electrode (CPE) for enhancing the sensitivity of DNA hybridization
detection. The immobilization of nano Au and TiO2 microsphere was investigated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The hybridization
events were monitored with EIS using [Fe(CN)6]3−/4− as indicator. The sequence-specific DNA of the 35S promoter from cauliflower mosaic virus (CaMV35S) gene was detected with
this DNA electrochemical sensor. The dynamic detection range was from 1.0×10−12 to 1.0×10−8 mol/L DNA and a detection limit of 2.3×10−13 mol/L could be obtained. The polymerase chain reaction (PCR) amplification of the terminator of nopaline synthase (NOS) gene
from the real sample of a kind of transgenic soybean was also satisfactorily detected.
Supported by the National Natural Science Foundation of China (Grant Nos. 20635020 and 20375020), Doctoral Foundation of the
Ministry of Education of China (Grant No. 20060426001) and Natural Science Foundation of Qingdao City (Grant No. 04-2-JZP-8) 相似文献
5.
Sheng Liu Miao Chen JinDu Li HaoBo Zhang JinQing Wang ShengRong Yang 《中国科学B辑(英文版)》2009,52(7):1009-1013
Hybridization of peptide nucleic acids probe containing azobenzene (NH2-TNT4, N-PNAs) with DNA was performed by covalently immobilizing of NH2-TNT4 in sequence on the 3-mercaptopropionic acid self-assembled monolayer modified gold electrode with the helps of N-(3-dimethylaminopropy1)-N′-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), and the hybrid was coded as N-PNAs/DNA. Using [Fe(CN)6]4−/3− (1:1) as the electrochemical indicator, the electrochemical properties of the N-PNAs self-assembled monolayer (N-PNAs-SAMs) and N-PNAs/DNA hybridization system under the conditions of before and after UV light irradiation were characterized with cyclic
voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectra (EIS). Results showed that the
redox currents decreased with the increase of irradiation time, suggesting that the ability of the charge transfer on the
electrode surface was weakened and the conformation of hybrid system had been changed, and the control of PNAs/DNA hybridization
could be realized by UV light irradiation.
Supported by the National Natural Science Foundation of China (Grant No. 50572107) and “Top Hundred Talents Program” of Chinese
Academy of Science 相似文献
6.
The sorption of anions H2PO4
−, HPO4
2−, PO4
3−, [Fe(CN)6]3−, and [Fe(CN)6]4− from aqueous solutions on the surface of FeIII and ZrIV oxyhydroxide hydrogels freshly precipitated at pH 4–13 was studied. The region of sorbate concentrations was from 0.00025
to 0.06 mol L−1. The plots of the anion uptakes vs. their equilibrium concentrations are represented by isotherms of the first type, which are well described by the Langmuir
equation if the quantity of the amount adsorbed is expressed as mol-site g−1. The maximum uptakes and constants of the Langmuir equation were calculated. The phosphate anions occupy the same number
of sorption sites on the sorbents precipitated at different pH. The average specific content of sorption sites for the ferro-
and zirconogels in the metastability period is independent of the pH of their precipitation, being 3.1·10−3 and 3.2·10−3 mol-site g−1, respectively. The [Fe(CN)6]3− and [Fe(CN)6]4− anions are sorbed only on the positively charged sites of the hydrogels and occupy not more than 2·10 mol-site g−1 in the studied interval of pH of precipitation.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1736—1741, August, 2005. 相似文献
7.
Yeong-Tarng Shieh Tzu-Yu Yu Tzong-Liu Wang Chien-Hsin Yang Wei-Tung Liao 《Colloid and polymer science》2012,290(1):1-9
In this study, we modified carbon nanotubes (CNTs) by grafting with poly(ethylene glycol) (PEG) using the “grafting to” method.
The PEG-grafted CNT (CNT-g-PEG) was cast on indium tin oxide (ITO) electrode to investigate the electrocatalytic activity
of CNT to the redox reactions of the Fe(CN)63−/4−as a probe using cyclic voltammetry and electrochemical impedance spectroscopy. The electrocatalytic activity of CNT was correlated
with CNT dispersion in the cast film on ITO as a function of pH of aqueous solution from which the film was cast. The CNT
dispersions in aqueous solutions of different pH and in the cast films were examined by visual observation and zeta potential,
scanning electron microscopy and transmission electron microscopy, respectively. At a pH in the range of 3–11 at which ITO
electrode was modified, two functionalized CNT (fCNT and CNT-g-PEG) were both found to electrocatalyze the redox reactions
of the Fe(CN)63−/4−probe and the PEG grafts in CNT-g-PEG could help CNT adhere to the electrode to obtain durable modified electrode. The more
uniform CNT dispersions in aqueous solutions and in the cast films appeared to have greater electrocatalytic acitivity. 相似文献
8.
We have developed a molecularly imprinted polymer (MIP) electrochemical sensor for entacapone (ETC) based on an electropolymerised polyphenylenediamine (Po-PD) on a glassy carbon electrode (GCE) surface. The direct electropolymerisation of the o-phenylenediamine monomer (o-PD) was carried out with ETC as a template. The steps of electropolymerization process, template removal and binding of the analyte were tested by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using [Fe(CN)6]3−/[Fe(CN)6]4 − as a redox probe. The operation of the sensor has been investigated by differential pulse voltammetry (DPV). Under optimal experimental conditions, the response of the DPV was linearly proportional to the ETC concentration between 1.0×10−7 and 5.0×10−6 M ETC with a limit of detection (LOD) of 5.0×10−8 M. The developed sensor had excellent selectivity without detectable cross-reactivity for levodopa and carbidopa. The MIP sensor was successfully used to detect ETC in spiked human serum samples. 相似文献
9.
Carboxylic group-functionalized carbon nanotubes (c-CNT) were modified on the surface of carbon paste electrode to obtain
a conducting precursor film. Positively charged poly-l-lysine (pLys) and negatively charged double-stranded DNA (dsDNA) were alternately adsorbed on the c-CNT-modified electrode,
forming (pLys/dsDNA)
n
layer-by-layer (LBL) films. Cyclic voltammetry and electrochemical impedance spectroscopy of the electroactive probe [Fe(CN)6]3−/4− could give the valuable dynamic information of multilayer films growth. The oxidative DNA damage induced by cadmium ion (Cd2+) in the LBL multilayer films was studied by differential pulse voltammetry (DPV) with methylene violet (MV) as the intercalation
redox probe. The electrochemical signals of MV on the multilayer films were effectively amplified via LBL technology. The
specific intercalation of MV into dsDNA base pairs and the amplified electrochemical response of MV, combined with the unique
feature of loading reversibility of MV in the DNA layer-by-layer films, made the difference in DPV response between the intact,
and damaged dsDNA films become pronounced. This biosensor exhibited that the (pLys/dsDNA)
n
films could be utilized for investigations of DNA damage. 相似文献
10.
Nongnoot Wongkaew Stefanie E. K. Kirschbaum Werasak Surareungchai Richard A. Durst Antje J. Baeumner 《Electroanalysis》2012,24(10):1903-1908
A new strategy of three‐electrode system fabrication in polymer‐based microfluidic systems is described here. Standard lithography, hot embossing and UV‐assisted thermal bonding were employed for fabrication and assembly of the microfluidic chip. For the electrode design the gold working (WE) and counter electrodes (CE) are placed inside a main channel through which the sample solution passes. A silver reference electrode (RE) is embedded in a small side channel containing KCl solution that is continuously pushed into the main channel. In the present work, the overall electrochemical set up and its microfabrication is described. Conditions including silver ion concentration, cyclic voltammetry (CV) settings, and the flow rate of KCl solution in the RE channel were optimized. The electrochemical performance of the three‐electrode system was evaluated by CV and also by amperometric oxidation of ferro hexacyanide ([Fe(CN)6]4?) and ruthenium bipyridyl ([Ru(bipy)3]2+) at 400 mV and 1200 mV, respectively. CV analysis using ferri/ferro hexacyanide showed a stable, quasi‐reversible redox reaction at the electrodes with 96 mV peak separation and an anodic/cathodic peak ratio of 1. Amperometric analysis of the electrochemical species resulted in linear correlation between analyte concentration and current response in the range of 0.5–15 µM for [Fe(CN)6]4?, and 0–1000 µM for [Ru(bipy)3]2+. Upon the given experimental conditions, the limit of detection was found to be 3.15 µM and 24.83 µM for [Fe(CN)6]4? and [Ru(bipy)3]2+, respectively. As a fully integrated three‐electrode system that is fabricated on polymer substrates, it has great applications in microfluidic‐based systems requiring stable electrochemical detection. 相似文献
11.
Stephanie A. Moore Subhash C. Bhattacharya Rama M. Palepu 《Journal of solution chemistry》2006,35(4):471-483
The photophyscial behavior of the dye Safranine T in the ground and excited states in aqueous mixtures of glycol oligomers was investigated by absorption and fluorescence spectroscopic techniques. The formation of a 1:1 complex in the excited state was inferred from fluorescence studies. The calculated equilibrium constants of the complex are directly proportional to the molar mass of the glycol. Microviscosity values of the aqueous glycol mixtures were determined by employing Auromine O as a fluorescence probe. Stokes shift values were correlated with the bulk dielectric constant and the microviscosity of the media. Also employing Stokes shifts, solvent parameters such as the Kowoser Z values and the intramolecular charge transfer energy, E
T
(30), were evaluated. The fluorescence quenching of Safranine T by the inorganic ions [Fe(CN)6]3−, [Fe(CN)6]4−, and [I]− in aqueous oligomer mixtures at a fixed concentration was investigated. The ions influenced the quenching process to different extents, and the efficiency of quenching of the dye in the glycol media for [Fe(CN)6]4− and [I]− ions follows the order EG > DEG > TEG > TTEG. In the case of ferricyanide ion the reverse order was observed. The microviscosity and bulk dielectric constant of the media played a major role in the collisional quenching process. 相似文献
12.
Yu. V. Pleskov M. D. Krotova V. P. Varnin I. G. Teremetskaya 《Russian Journal of Electrochemistry》2010,46(3):325-330
The effect of nondiamond (sp
2-) carbon admixture on the surface of polycrystalline boron-doped CVD-diamond electrodes on their electrochemical behavior
was studied by comparing the films grown under similar conditions, yet of different thickness. It is shown that with the decreasing
of the film thickness (hence, with the increasing of the nondiamond carbon content therein) its surface acquired electrochemical
activity: the transfer coefficients of reactions in the [Fe(CN)6]3−/4− redox system increased, the oxygen anodic evolution overvoltage decreased, the differential capacitance increased; on the
whole, the diamond electrode demonstrated increasingly better pronounced metal-like behavior. 相似文献
13.
Roshan Khadka Nihan Aydemir Colm Carraher Cyril Hamiaux Paul Baek Jamal Cheema Andrew Kralicek Jadranka Travas‐Sejdic 《Electroanalysis》2019,31(4):726-738
This article aims to demonstrate an electrochemically stable and reliable gold electrode‐electrolyte system to develop an insect odorant receptor (Drosophila melanogaster Or35a) based bioelectronic nose. Cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS) of bare gold electrodes, after modification with the self‐assembled monolayer (SAM) of 6‐mercaptohexanoic acid (MHA) and after immobilization with Or35a integrated into the lipid bilayers of liposomes were conducted in the presence of four different redox probes. Potassium ferri/ferrocyanide [Fe(CN)6]3?/[Fe (CN)6]4? and hydroquinone (H2Q) redox probes revealed variable and irreversible signals at the time scale of our measurements, with atomic force microscopy (AFM) images and x‐ray photoelectron spectroscopy (XPS) results suggesting gold surface etching due to the presence of CN? ions in case of [Fe(CN)6]3?/[Fe (CN)6]4?. Although the hexaammineruthenium complex showed stable electrochemical behaviour at all stages of biosensor development, changes in CV and EIS readings after each surface modifications were insignificant. PBS buffer as a non‐Faradaic medium, was found to provide reliable systems for electrochemical probing of modified gold electrodes with Or35a/liposomes in aqueous media. Using this system, we have shown that this novel biosensor can detect its known odorant E2‐hexenal selectively compared to methyl salicylate down to femtomolar concentration. 相似文献
14.
The quenching of fluorescence of the free-base tetraphenylporphyrin, H2TPP, and its metal derivatives, MgTPP and ZnTPP by diverse iron(III) complexes, [Fe(CN)6]3−, Fe(acac)3, [Fe(mnt)2]−, Fe(Salen)Cl, [Fe4S4(SPh)4]2−·, FeTPPCl and [Fe(Cp)2]+ has been studied both in homogeneous medium (CH3CN) and micellar media, SDS., CTAB and Triton X-100. The quenching efficiencies are analysed in terms of diffusional encounters
and it has been possible to separate static quenching components. The quenching constants are dependent on the nature of the
ligating atoms around iron(III) and also on the extent of π-conjugation of the ligands. The quenching mechanism has been investigated
using steady-state irradiation experiments. Evidence for oxidative quenching by iron(III) complexes was obtained, though the
spin multiplicities of the excited electronic states of iron(III) complexes permit both energy and electron transfer mechanisms
for quenching of the singlet excited state of the porphyrins. 相似文献
15.
Four pyridinecarboxamide iron dicyanide building blocks and one Mn(III) compound have been employed to assemble cyanide-bridged
heterometallic complexes, resulting in a series of trinuclear cyanide-bridged FeIII–MnII complexes: {[Mn(DMF)2 (MeOH)2][Fe(bpb)(CN)2]2}·2DMF (1), {[Mn(MeOH)4][Fe(bpmb)(CN)2]2}·2MeOH·2H2O (2), {[Mn(MeOH)4][Fe(bpdmb)(CN)2]2}·2MeOH·2H2O (3) and {[Mn(MeOH)4][Fe(bpClb)(CN)2]2}·4MeOH (4) (bpb2− = 1,2-bis(pyridine-2-carboxamido)benzenate, bpmb2− = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpdmb2− = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, bpClb2− = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate). Single-crystal X-ray diffraction analysis shows their similar sandwich-like
structures, in which the two cyanide-containing building blocks act as monodentate ligands through one of their two cyanide
groups to coordinate the Mn(II) center. Investigation of the magnetic properties of these complexes reveals antiferromagnetic
coupling between the neighboring Fe(III) and Mn(II) centers through the bridging cyanide group. A best fit to the magnetic
susceptibilities of complexes 1 and 3 gave the magnetic coupling constants J = −1.59(2) and −1.32(4) cm−1, respectively. 相似文献
16.
I. A. Koval' K. B. Yatsimirskii S. Trofimenko V. V. Pavlishchuk 《Theoretical and Experimental Chemistry》1998,34(6):323-326
The new trinuclear complex K{(CoTpt-Bu)[Fe(CN)6](CoTpt-Bu)}, in which the initial structural fragments are linked by CN− bridges, was synthesized by the directed stitching of mononuclear complexes, one of which was [Fe(CN)6]3− while the other was cobalt(II) tris(3-tert-butyl-l-pyrazolyl)borate ([(CoTpt-Bu)]+). The magnetic moment of K{(CoTpt-Bu)[Fe(CN)6](CoTpt-Bu)} at 292 K was 8.07 μβ (S=7/2), indicating the absence of antiferromagnetic exchange interactions in the trinuclear complex.
Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 6, pp. 351–354, November–December, 1998. 相似文献
17.
[MoVIO2(S2C2(CN)2)2]2− (┘1) and [MoIVO(S2C2(CN)2)2]2− (2) mimick oxidoreductase enzymatic activities of sulphite oxidase with biological electron donor, SO
3
2−
, andin vitro electron acceptor, [Fe(CN)6]3−, demonstrating proton coupled electron transfer reaction in water and inhibition of the oxidation of (2) in the presence of KCN. The sulphite exidizing system is characterized by substrate saturation kinetics indicating the biological
significance of the reactions 相似文献
18.
An amperometric glucose biosensor was developed based on the immobilization of glucose oxidase in the organically modified
silicate (ormosil)-polyvinyl acetate (PVA) matrix onto a Prussian Blue (PB)-modified glassy carbon electrode. A higher stability
PB-modified electrode was prepared by the electrochemical deposition of FeCl3, K3[Fe(CN)6] and ethylenediamine tetraacetic acid (EDTA) under cyclic voltammetric (CV) conditions. The effects of the potential range
of CV conditions, electrolyte cations, applied potential, pH, temperature and co-existing substances were investigated. The
detection limit of the glucose biosensor was 8.1 μmol·L−1 (S/N = 3) with a linear range from 20 μmol·L−1 to 2 mmol·L−1 (R = 0.9965). The biosensor presented a fast response and good selectivity. Additionally, excellent reproducibility and stability
of the biosensor were observed.
Supported by the National High Technical Development Project (863 project) Foundation (Grant No. 2006AA09Z160) and the National
Natural Science Foundation of China (Grant No. 20775064) 相似文献
19.
Self-assembly of the precursor [Cu(L)]2+ (L = 3,10-dipropyl-1,3,5,8,10,12-hexaazacyclotetradecane) with hexacyanometalate [Fe(CN)6]3− produces a 3-D cyano-bridged Cu(II)–Fe(III) bimetallic assembly, [CuL]2[Fe(CN)6]ClO4 · H2O (1), characterized by single-crystal X-ray diffraction studies, and magnetic measurements. The crystallographic determination
reveals that each hexacyanoferromate(III) ion connects four copper(II) ions using four co-planar CN− groups which axially coordinate to the copper ion in a trans fashion forming trans-CuL(N≡C)2 moieties in (1). Magnetic studies reveal that (1) displays a ferromagnetic interaction between Cu(II) and Fe(III) through the CN linkage. 相似文献
20.
A new approach for a simple electrochemical detection of PAT gene fragment is described. Poly(2,6-pyridinedicarboxylic acid) (PDC) modified glassy carbon electrode (GCE) was prepared by potential scan electropolymerization in an aqueous solution. Mg2 ions were incorporated by immer-sion of the modified electrode in 0.5 mol/L aqueous solution of MgCl2 to complete the preparation of a generic "activated" electrode ready for binding the probe DNA. The ssDNA was linked to the conduct-ing polymer by forming a bidentate complex between the carboxyl groups on the polymer and the phosphate groups of DNA via Mg2 . DNA immobilization and hybridization were characterized with dif-ferential pulse voltammetry (DPV) by using methylene blue (MB) as indicator and electrochemical im-pedance spectroscopy (EIS). The EIS was of higher sensitivity for DNA detection as compared with voltammetric methods in our strategy. The electron transfer resistance (Ret) of the electrode surface in EIS in [Fe(CN)6]3-/4- solution increased after the immobilization of the DNA probe on the Mg/PDC/GCE electrode. The hybridization of the DNA probe with complementary DNA (cDNA) made Ret increase further. The difference between the Ret at ssDNA/Mg/PDC/GCE and that at hybridization DNA modified electrode (dsDNA/Mg/PDC/GCE) was applied to determine the specific sequence related to the target PAT gene with the dynamic range comprised between 1.0 × 10-9 and 1.0 × 10_5 mol/L. A detection limit of 3.4 × 10-10 mol/L of oligonucleotides can be estimated. 相似文献