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1.
Zhao Yang Gao-Shao Cao Jian Xie Xin-Bing Zhao 《Journal of Solid State Electrochemistry》2012,16(3):1271-1277
LiMnPO4, with a particle size of 50–150 nm, was prepared by oleic acid-assisted solid-state reaction. The materials were characterized
by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. The electrochemical
properties of the materials were investigated by galvanostatic cycling. It was found that the introduction of oleic acid in
the precursor led to smaller particle size and more homogeneous size distribution in the final products, resulting in improved
electrochemical performance. The electrochemical performance of the sample could be further enhanced by Co doping. The mechanism
for the improvement of the electrochemical performance was investigated by Li-ion chemical diffusion coefficient
( [(D)\tilde]\textLi ) \left( {{{\tilde{D}}_{\text{Li}}}} \right) and electrochemical impedance spectroscopy measurements. The results revealed that the
[(D)\tilde]\textLi {\tilde{D}_{\text{Li}}} values of LiMnPO4 measured by cyclic voltammetry method increase from 9.2 × 10−18 to 3.0 × 10−17 cm2 s−1 after Co doping, while the charge transfer resistance (R
ct) can be decreased by Co doping. 相似文献
2.
Obuchowska A 《Analytical and bioanalytical chemistry》2008,390(5):1361-1371
A new electrochemical method for the quantitation of bacteria that is rapid, inexpensive, and amenable to miniaturization
is reported. Cyclic voltammetry was used to quantitate M. luteus, C. sporogenes, and E. coli JM105 in exponential and stationary phases, following exposure of screen-printed carbon working electrodes (SPCEs) to lysed
culture samples. Ferricyanide was used as a probe. The detection limits (3s) were calculated and the dynamic ranges for E. coli (exponential and stationary phases), M. luteus (exponential and stationary phases), and C. sporogenes (exponential phase) lysed by lysozyme were 3 × 104 to 5 × 106 colony-forming units (CFU) mL−1, 5 × 106 to 2 × 108 CFU mL−1 and 3 × 103 to 3 × 105 CFU mL−1, respectively. Good overlap was obtained between the calibration curves when the electrochemical signal was plotted against
the dry bacterial weight, or between the protein concentration in the bacterial lysate. In contrast, unlysed bacteria did
not change the electrochemical signal of ferricyanide. The results indicate that the reduction of the electrochemical signal
in the presence of the lysate is mainly due to the fouling of the electrode by proteins. Similar results were obtained with
carbon-paste electrodes although detection limits were better with SPCEs. The method described herein was applied to quantitation
of bacteria in a cooling tower water sample.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
3.
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
4.
We have compared the resistivity, ρ, of sulfonated polyaniline (SPAN) prepared via three different synthetic routes: electrochemical synthesis with a supporting
electrolyte (camphorsulfonic acid), ρ
=340 Ω·m; electrochemical synthesis without a supporting electrolyte, ρ
=530 Ω·m, and; chemical synthesis, ρ
=166 Ω·m. Independent of the metal contact (Al, Au, Cu), SPAN forms ohmic contacts with the metal and the contact resistance r
c
~5 Ω does not correlate with the metal's work function.
Electronic Publication 相似文献
5.
Huaibing Sun Yungui Chen Chenghao Xu Ding Zhu Lihong Huang 《Journal of Solid State Electrochemistry》2012,16(3):1247-1254
Spinel powders of LiMn2−x
RE
x
O4 (RE = La, Ce, Nd, Sm; 0 ≤ x ≤ 0.1) have been synthesized by solid-phase reaction. The structure and electrochemical properties of these electrode materials
were characterized by X-ray diffraction (XRD), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge–discharge
experiment. The part substitution of rare-earth element RE for Mn in LiMn2O4 decreases the lattice parameter, resulting in the improvement of structural stability, and decreases the charge transfer
resistance during the electrochemical process of LiMn2O4. As a result, the cycle ability, 55 °C high-temperature and high-rate performances of LiMn2−x
RE
x
O4 electrode materials are significantly improved with increasing RE addition, compared to the pristine LiMn2O4. 相似文献
6.
Jing Zhao Wei Zhu Tao Liu Jinghua Yang Genxi Li 《Analytical and bioanalytical chemistry》2010,397(2):695-701
Homocysteine thiolactone modification is a unique process of posttranslational protein modification as well as a significant
clinical indicator of cardiovascular and neurovascular diseases, so we report a new method in this paper to sensitively monitor
such a modification using horse heart cytochrome c as a model protein. After the modification has been confirmed by UV–vis spectroscopy and ESI-MS, N-linked cytochrome c is then covalently assembled onto the surface of a gold electrode via the resulted homocysteine thiol group, thus electrochemical
techniques, especially differential pulse voltammetry, have been employed and proven to provide an efficient way to probe
into the modification of the protein. While the immobilized protein can exhibit well-defined voltammetric response, the signal
of the modified cytochrome c is positively correlated to the concentration of homocysteine-thiolactone. The detectable electrochemical signal can be attained
with the minimum concentration of 5 × 10−5 M homocysteine-thiolactone. Furthermore, screening of N-homocysteinylation inhibitors can be also feasible since the electrochemical waves linearly decrease with the concentration
of an inhibitor pyridoxal 5-phosphate. The limit of detection for the inhibitors can be about 1 × 10−5 M. 相似文献
7.
In pH 3.5 Britton—Robinson buffer solution double-stranded (ds) DNA can react with malachite green (MG) to form an interaction
complex, which resulted in the decrease of the electrochemical response of MG, MG had a well-defined second-order derivative
linear sweep voltammetric peak at −0.73 V (vs. SCE). After the addition of dsDNA into MG solution, the reductive peak current decreased with the positive shift of peak
potential, which was the typical characteristic of intercalation. Based on the interaction, an indirect electrochemical determination
method for dsDNA was established. The optimum conditions for the reaction were investigated and there were little or no interferences
from the commonly coexisting substances. The decrease of peak current was linear with the concentration of dsDNA over the
range of 0.8–12.0 μg cm−3 with the linear regression equation as ΔI
p″/nA = 91.70 C/(μg cm−3) + 74.55 (n = 10, γ = 0.990). The detection limit was calculated as 0.46 μg cm−3 (3σ). The method had high sensitivity and was further applied to the dsDNA synthetic samples with satisfactory result. The interaction
mechanism was discussed with the intercalation of DNA-MG to form a supramolecular complex and the stoichiometry of the supramolecular
complex was calculated by electrochemical method with the binding number 3 and the binding constant 2.35 × 1015 (mol dm−3)−3. 相似文献
8.
Inhibition effect of imidazole derivative 1,7′-dimethyl-2′-propyl-1H,3′H-2,5′-bibenzo[d]imidazole (DPBI) against mild steel corrosion in 1 M HCl solutions was evaluated using the conventional mass loss method,
potentiodynamic polarization, linear polarization, and electrochemical impedance spectroscopy. The mass loss results showed
that DPBI is an excellent corrosion inhibitor; electrochemical polarizations data revealed the mixed mode of inhibition; and
the results of electrochemical impedance spectroscopy showed that the change in the impedance parameters, charge transfer
resistance, and double layer capacitance with the change in the concentration of the inhibitor is due to the adsorption of
the molecule leading to the formation of a protective layer on the surface of mild steel. The inhibition action of this compound
was assumed to occur via adsorption on the steel surface through the active centers of the molecule. 相似文献
9.
Samaneh Kharian Nader Teymoori Mohammad A. Khalilzadeh 《Journal of Solid State Electrochemistry》2012,16(2):563-568
In this work, we describe an electrochemical method using p-chloranil as a mediator and multi-wall carbon nanotube and TiO2 as sensors for sensitive determination of epinephrine (EP) in aqueous solution at pH = 10.0. It has been found that under
optimum condition (pH 10.0) in cyclic voltammetry, the oxidation of EP occurred at a potential about 171 mV less positive
than that unmodified carbon nanotube paste electrode. The diffusion coefficient (D) and the kinetic parameters, such as electron transfer coefficient, (α) and heterogeneous rate constant (k
h) for EP were also determined using electrochemical approaches. The electrocatalytic currents increase linearly with the EP
concentration over the range 0.6–135 μM. The detection limits for EP will be equal to 0.25 μM. The relative standard deviation
percentage values for 10.0 and 15.0 μM EP were 1.7% and 1.9%, respectively. Finally, this modified electrode was also examined
as a selective, simple, and precise new electrochemical sensor for the determination of EP in real sample such as urine and
epinephrine injection solution. 相似文献
10.
The electrochemical behavior of ciprofloxacin (CFX) and its interaction with the natural calf thymus DNA (ctDNA) is studied
by using pulse difference voltammetry on a carbon electrode. CFX shows a well-defined oxidative peak at + 0.88 V. As a result
of reaction with ctDNA,the oxidative peak of CFX decreased markedly. According to the electrochemical equation deduced in
this paper, the binding constant of 1.36 × 105 (mol/L)−1 and the binding size of 1.94 (base pairs) of CFX with ctDNA were obtained by nonlinear fit analysis of the electrochemical
data. The mechanism of the interaction was explored.
__________
Translated from Journal of Zhejiang University (Science Edition), 2007, 34(3): 330–334 [译自: 浙江大学学报(自然科学版)] 相似文献
11.
Jianping Li Xiongzhi Wu Yong Yu Shangwang Le 《Journal of Solid State Electrochemistry》2009,13(12):1811-1818
Gold electrode with self-assembled D,L-cysteine grafted β-cyclodextrin sulfonic acid (Cys-β-CD∼SO3) layer was fabricated and used to investigate the electrochemical behavior of dopamine. The experimental results indicated
that the self-assembled Cys-β-CD∼SO3 layer modified gold electrode has selective electrochemical response to dopamine with high sensitivity and excellent tolerance
of ascorbic acid, which is the most common accompanying component in biological samples. Dopamine could be accurately determined
in the concentration range of 1–200 μM in the presence of ascorbic acid of 5 mM. The relative standard deviation of 1.9% (n = 5) was achieved at a dopamine concentration of 5 × 10−5 M. The proposed sensor was successfully applied to the determination of dopamine in human blood serum samples. 相似文献
12.
A novel and reliable direct electrochemical method was established for the detection of adenine, based on the differential
pulse anodic stripping response at a poly(amidosulfonic acid) (poly-ASA)-modified glassy carbon electrode (GCE) fabricated
by electropolymerization. The characterization of electrochemically synthesized poly-ASA film was investigated by atomic force
microscopy, electrochemical impedance spectroscopy, and voltammetric methods. This poly-ASA-modified GCE could greatly enhance
the detection sensitivity of adenine. At optimum conditions, the anodic peak exhibits a good linear concentration dependence
in the range from 3.0 × 10−8 to 1.0 × 10−6 M (r = 0.9994). The detection limit is 8.0 × 10−9 M (S/N = 3). The proposed method could be used to determinate the adenine in tablets of vitamin B4 with satisfactory results. 相似文献
13.
The electrocatalytic oxidation of quinine sulfate (QS) was investigated at a glassy carbon electrode, modified by a gel containing
multiwall carbon nanotubes (MWCNTs) and room-temperature ionic liquid of 1-Butyl-3-methylimidazolium hexafluorophate (BMIMPF6) in 0.10 M of phosphate buffer solution (PBS, pH 6.8). It was found that an irreversible anodic oxidation peak of QS with
E
pa as 0.99 V appeared at MWCNTs-RTIL/glassy carbon electrode (GCE). The electrode reaction process was a diffusion-controlled
one and the electrochemical oxidation involved two electrons transferring and two protons participation. Furthermore, the
charge-transfer coefficient (α), diffusion coefficient (D), and electrode reaction rate constant (k
f) of QS were found to be 0.87, 7.89 × 10−3 cm2⋅s−1 and 3.43 × 10−2 s−1, respectively. Under optimized conditions, linear calibration curves were obtained over the QS concentration range 3.0 × 10−6 to 1.0 × 10−4 M by square wave voltammetry, and the detection limit was found to be 0.44 μM based on the signal-to-noise ratio of 3. In
addition, the novel MWCNTs-RTIL/GCE was characterized by the electrochemical impedance spectroscopy and the proposed method
has been successfully applied in the electrochemical quantitative determination of quinine content in commercial injection
samples and the determination results could meet the requirement. 相似文献
14.
Chunhai Yang Shenghui Zhang Yingxuan Liu Wensheng Huang 《Frontiers of Chemistry in China》2008,3(3):353-358
A multi-wall carbon nanotubes (MWNTs)-Nafion film-coated glassy carbon electrode (GCE) was fabricated and the electrochemical
behavior of ofloxacin on the MWNTs-Nafion film-coated GCE were investigated by cyclic voltammetry (CV), linear sweep voltammetry
(LSV) and electrochemical impedance spectroscopy (EIS). The oxidation peak current of ofloxacin increased significantly on
the MWNTs-Nafion film modified GCE compared with that using a bare GCE. This nano-structured film electrode exhibited excellent
enhancement effects on the electrochemical oxidation of ofloxacin. A well-defined oxidation peak attributed to ofloxacin was
observed at 0.97 V and was applied to the determination of ofloxacin. The oxidation peak current was proportional to ofloxacin concentration
in the ranges 1.0 × 10−8 to 1.0 × 10−6 mol/L and 1.0 × 10−6 to 2.0 × 10−5 mol/L. A detection limit of 8.0 × 10−9 mol/L was obtained for 400 s accumulation at open circuit (S/N = 3). This method for the detection of ofloxacin in human
urine was satisfactory.
__________
Translated from Chinese Journal of Applied Chemistry, 2007, 24(5): 540–545 [译自: 应用化学] 相似文献
15.
A novel hydrogen peroxide (H2O2) biosensor was developed by immobilizing hemoglobin on the gold colloid modified electrochemical pretreated glassy carbon
electrode (PGCE) via the bridging of an ethylenediamine monolayer. This biosensor was characterized by UV-vis reflection spectroscopy
(UV-vis), electrochemical impendence spectroscopy (EIS) and cyclic voltammetry (CV). The immobilized Hb exhibited excellent
electrocatalytic activity for hydrogen peroxide. The Michaelis–Menten constant (K
m) was 3.6 mM. The currents were proportional to the H2O2 concentration from 2.6 × 10−7 to 7.0 × 10−3 M, and the detection limit was as low as 1.0 × 10−7 M (S/N = 3). 相似文献
16.
Self-assembled monolayer gold electrode for surfactant analysis 总被引:2,自引:0,他引:2
Marc Gerlache Zühre Senturk Guy Quarin Jean-Michel Kauffmann 《Journal of Solid State Electrochemistry》1997,1(2):155-160
A gold electrode coated with a self-assembled monolayer of octane-thiol (SAM/Au) has been used as an amperometric detector
for the determination of surfactants. This detector operated in the presence of a high percentage of organic solvent and was
adapted to an HPLC System. At the SAM/Au, the electrochemical response of an electroactive tracer (potassium ferricyanide)
was completely inhibited, but, in the presence of a cationic surfactant, the electrochemical reduction was progressively restored.
In flow injection analysis, using the SAM/Au in an amperometric flow-through detector polarised at 0.0 V vs Ag/AgCl, a linear
response (i=f{[surfactant]}) was observed for cationic surfactants e.g. cetylpyridinium chloride in the concentration range 2 × 10−6–1 × 10−3 M. The electrochemical data along with the determination of the ion pair stoichiometry between the redox tracer and the surfactant
suggest an electrochemical response related to ion pair formation and governed by electron transfer by tunneling effect.
Received: 28 January 1997 / Accepted: 7 March 1997 相似文献
17.
Determination of Aldehydes and Ketones in Fuel Ethanol by High-Performance Liquid Chromatography with Electrochemical Detection 总被引:1,自引:0,他引:1
A. A. Saczk L. L. Okumura M. F. de Oliveira M. V. B. Zanoni N. R. Stradiotto 《Chromatographia》2006,63(1-2):45-51
A new methodology was developed for analysis of aldehydes and ketones in fuel ethanol by high-performance liquid chromatography
(HPLC) coupled to electrochemical detection. The electrochemical oxidation of 5-hydroxymethylfurfural, 2-furfuraldehyde, butyraldehyde,
acetone and methyl ethyl ketone derivatized with 2,4-dinitrophenylhydrazine (DNPH) at glassy carbon electrode present a well
defined wave at +0.94 V; +0.99 V; +1.29 V; +1.15 V and +1.18 V, respectively which are the basis for its determination on
electrochemical detector. The carbonyl compounds derivatized were separated by a reverse-phase column under isocratic conditions
with a mobile phase containing a binary mixture of methanol / LiClO4(aq) at a concentration of 1.0 × 10−3 mol L−1 (80:20 v/v) and a flow-rate of 1.1mL min−1 . The optimum potential for the electrochemical detection of aldehydes-DNPH and ketones-DNPH was +1.0 V vs. Ag/AgCl. The
analytical curve of aldehydes-DNPH and ketones-DNPH presented linearity over the range 5.0 to 400.0 ng mL−1, with detection limits of 1.7 to 2.0 ng mL−1 and quantification limits from 5.0 to 6.2 ng mL−1, using injection volume of 20 μL. The proposed methodology was simple, low time-consuming (15 min/analysis) and presented
analytical recovery higher than 95%. 相似文献
18.
Yu. N. Ogibin A. O. Terent'ev A. I. Ilovaisky G. I. Nikishin 《Russian Chemical Bulletin》1999,48(11):2091-2099
Electrolysis of 2-oxa- and 2,5-dioxabicyclo[n.4.0]alk-1(6)0enes (n=4, 10) under conditions of direct undivided anodic oxidation in methanol results in their electrochemical mono-and dimethoxylation;
electrolysis of the corresponding 2-oxa-and 2,5-dioxabicycloalkanes involves electrochemical cleavage of the bridging carbon—carbon
bonds followed by electrooxidative transformation into methyl ω-(2-methoxytetrahydrofuryl)-, ω-(dimethoxy-methyl)-, and ω-(1,3-dioxolan-2-yl)alkanoates.
For preliminary communication, see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2115–2122, November, 1999. 相似文献
19.
Jian-Fang Lu Ling Wang Qiong-Yu Lai Hong-Yan Chu Yan Zhao 《Journal of Solid State Electrochemistry》2009,13(12):1803-1810
The copolymers were synthesized with different molar ratios of m-phenylenediamine to aniline (R for short) by a chemical oxidation method. The products were first used as electrochemical activity materials of the supercapacitor.
Capacitive behaviors of the prepared copolymers in 1 mol·L−1 H2SO4 electrolyte were examined by electrochemical impedance spectroscopy, cyclic voltammeter, and galvanostatic charge/discharge.
The relationship of molar ratios with capacitive property of the prepared products was investigated too. The results showed
that the product with R of 2:98 displayed better electrochemical properties than that of the other products. Compared with the synthesized polymer
in the absence of m-phenylenediamine, the polymerized copolymer with R of 2:98 exhibited the initial specific capacitance value of 475 F·g−1, which increased by nearly 10.1% than that of the former at a current density of 200 mA·g−1 in 1 mol·L−1 H2SO4 electrolyte in the potential range of −0.3 to 0.7 V. The discharge specific capacitance value of the copolymer remained 300 F·g−1 after 1,000 cycles, exhibiting a good cycling performance and the structure stability. 相似文献
20.
Frank Marken Alastair N. Blythe Jay D. Wadhawan Richard G. Compton Steven D. Bull Robin T. Aplin Stephen G. Davies 《Journal of Solid State Electrochemistry》2001,5(1):17-22
The effect of the structure of the organic precursor molecule on the electroinsertion of anions and on the formation of materials
in the ionic liquid state is compared for three compounds, para-N, N, N′, N′-tetrahexylphenylenediamine (p-THPD), meta-N, N, N′, N′-tetrahexylphenylene diamine (m-THPD), and para-N, N, N′, N′-tetrakis(6-methoxyhexyl)phenylenediamine (p-TMHPD), by characterising their condensed phase voltammetric properties in aqueous media. The electrochemically driven anion
insertion in p-THPD and p-TMHPD in the presence of ClO4
−, F−, Cl−, Br−, I−, and SO4
2− is shown to be extremely sensitive to structure. The introduction of the methoxy end groups in p-TMHPD causes (1) a considerable shift to more negative electroinsertion potentials, (2) a less stable response which upon
continuous cycling decreases, and (3) considerably lower anion selectivity. For the insertion of sulfate, only p-TMHPD yields an electrochemical response which is shown to be consistent with insertion of the dianion SO4
2−. The electrochemical oxidation of a deposit of m-THPD is accompanied by anion insertion and a chemical reaction step in an EC-type electrochemical process. The product of
the chemical step is electrochemically active and results in a new reversible electroinsertion process. Starting materials
and products of the microdroplet reactions are characterised by Maldi-TOF mass spectrometry and a reaction mechanism based
on condensed phase polymerisation is proposed.
Received: 15 November 1999 / Accepted: 2 December 1999 相似文献