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1.
Carbon nanotube electrodes were fabricated using powder microelectrode method, and the carbon nanotube powder microelectrodes (CNTPMEs) were characterized by the electro-oxidation and electro-reduction of nitrite. It was found that the kinetics of oxidation and reduction were greatly improved at CNTs compared with that at conventional graphite, indicating that CNTs could catalyze the electrochemical process of nitrite. The kinetic parameters of these process at CNTs were calculated, i.e. k was 0.593 cm s−1, and (1-α)nα was 0.501±0.018 for the nitrite oxidation. This CNTPME was also used as a nitrite carbon nanotube sensor, and the results showed that the detection limit was 8 μM. 相似文献
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Multi-walled carbon nanotube (MWNT)/polyaniline (PANI) composite films with good uniformity and dispersion were prepared by electrochemical polymerization of aniline containing well-dispersed MWNTs. The results of transmission electron microscopy (TEM) show that aniline can be used to solve MWNTs via formation of donor–acceptor complexes. Scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) revealed that the well arrangement of PANI-coated MWNTs in these films facilitated improved electron and ion transfer relative to pure PANI films and this may be due to the strong interaction between MWNTs and PANI. 相似文献
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Jahan Bakhsh Raoof Reza Ojani Maryam Ramine 《Journal of Solid State Electrochemistry》2009,13(9):1311-1319
A p-duroquinone (tetramethyl-p-benzoquinone) modified carbon paste electrode (DMCPE) was employed to study the electrocatalytic reduction of nitrite in
aqueous solutions using cyclic voltammetry (CV), double potential-step chronoamperometry, and differential pulse voltammetry
(DPV). It has found that under an optimum condition (pH 1.00), the reduction of nitrite at the surface of DMCPE occurs at
a potential of about 660 mV less negative than that of an unmodified carbon paste electrode (CPE). The catalytic rate constant,
k′h, based on Andrieux and Saveant theoretical model was calculated as for scan rate 10 mV s-1. Also, the apparent diffusion coefficient, D
app, was found as 2.5 × 10–10 and 3.61 × 10–5 cm2 s-1
for p-duroquinone in carbon paste matrix and nitrite in aqueous buffered solution, respectively. The values for αnα were estimated to be −0.65 and −0.19 for the reduction of nitrite at the surface of DMCPE and CPE, respectively. The electrocatalytic
reduction peak currents showed a linear dependence on the nitrite concentration, and a linear analytical curve was obtained
in the ranges of 5.0 × 10–5 M to 8.0 × 10–3 M and 6.0 × 10–6 M to 8.0 × 10–4 M of nitrite concentration with CV and DPV methods, respectively. The detection limits (2σ) were determined as 2.5 × 10–5 M and 4.3 × 10–6 M by CV and DPV methods. This method was also applied as a simple, selective and precise method for determination of nitrite
in real samples (the weak liquor from the wood and paper factory of Mazandaran province in Iran) by using a standard addition
method. 相似文献
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This paper describes the development and the application of a novel carbon nanotube/poly(methyl methacrylate) (CNT/PMMA) composite electrode as a sensitive amperometric detector of CE. The composite electrode was fabricated on the basis of the in situ polymerization of a mixture of CNT and prepolymerized methylmethacrylate in the microchannel of a piece of fused-silica capillary under heat. The performance of this unique system has been demonstrated by separating and detecting honokiol and magnolol in traditional Chinese medicine, Cortex Magnoliae Officinalis. Factors influencing their separation and detection processes were examined and optimized. Honokiol and magnolol were well separated within 7 min in a 40 cm long capillary at a separation voltage of 15 kV using a 50 mM borate buffer (pH 9.2). The new CNT-based CE detector offered significantly lower operating potentials, yielded substantially enhanced S/N characteristics, and exhibited resistance to surface fouling and hence enhanced stability. It demonstrated long-term stability and reproducibility with RSDs of less than 5% for the peak current (n = 9) and should also find a wide range of applications in microchip CE, flowing injection analysis, and other microfluidic analysis systems. 相似文献
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《Arabian Journal of Chemistry》2019,12(7):946-956
The voltammetric (CV and DPV) behavior of multi-walled carbon nanotube/Nafion composite coupled with a glassy carbon electrode was investigated for the determination of 2,4-dichlorophenol. The structural and morphological evaluation by XRD and FESEM revealed that the acid treated MWCNT retained their morphology without any structural change. The existence of the possible functional groups was investigated by FTIR and Raman spectroscopy. Compared to bare GCE, a significantly reduced interfacial charge transfer resistance was noticed for MWCNT/Nafion/GCE by electrochemical impedance spectroscopy (EIS). The use of Nafion not only contributed to the non-covalent functionalization of MWCNT, but also protected the electrode surface against the polymerization of phenoxy radicals forming a passivating film. For MWCNT/Nafion/GCE, the combination of anti-passivating ability and excellent catalytic properties resulted in the rapid and direct electrochemical determination of 2,4-DCP. Under optimal experimental conditions, the DPV responses for MWCNT/Nafion/GCE is linear over the 1–150 μmol/L range with a detection limit (S/N = 3) of 0.01 μmol/L. The presence of many interfering species had no influence on the signals of 2,4-DCP. The proposed sensor was successfully tested for the determination of 2,4-DCP in tap water samples and the recovery was in the range of 99.0–102.5%. 相似文献
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Hong Xia Luo Zhi Xin Guo Nan He 《中国化学快报》2007,18(7):861-864
Calf thymus DNA was electrochemically oxidized at a multi-walled carbon nanotube modified electrode. The potentials for DNA oxidation at pH 7.0 were 0.71 and 0.81 V versus SCE, corresponding to the oxidation of guanine and adenine residues, respectively. The initial 6e-oxidation of adenine, observed in the first scan, resulted a quasi-reversible 2e-redox process of the oxidation product in the following scans. 相似文献
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应用循环伏安法和线性扫描伏安法研究了双氯芬酸钠在多壁碳纳米管修饰电极上的电化学行为,建立了一种直接测定双氯芬酸钠的电分析方法.在0.1 mol/L HClO4溶液中,双氯芬酸钠的氧化峰电位在0.38 V(vs Ag/AgCl),峰电流与浓度在2.0×10-7 mol/L~7.0 × 10-6 mol/L范围内呈线性关系,开路富集3 min后检出限为9.0×10-8 mol/L.5×10-6 mol/L双氯芬酸钠溶液平行测定10次的相对标准偏差(RSD)为4.5%.已用于扶他林片剂中双氯芬酸钠的测定. 相似文献
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Jing Li 《Microchemical Journal》2007,87(1):41-46
Pt nanoclusters were deposited in polypyrrole (PPy) nanowires by cyclic voltammetry method, fabricating a PPy-Pt nanocomposite on glassy carbon electrode (PPy-Pt/GCE). The electrocatalytic reduction of nitrite at PPy-Pt/GCE has been investigated using 0.5 M H2SO4 solution. The sensor exhibited excellent electrocatalytic activity toward nitrite reduction. In acidic medium, the cyclic voltammetry at 20 mV s− 1 gave a nitrite reduction peak at − 0.124 V with 0.566 μA μM− 1 current sensitivity in the range of 5.0 × 10− 7-1.0 × 10− 3 M. The detection limit was 1.5 × 10− 7 M (s/n = 3). The proposed method was successfully applied in the detection of nitrite in real water samples and obtained satisfactory results. The PPy-Pt composite modified electrode had good storage stability, reproducibility and anti-interference ability. 相似文献
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运用循环伏安法与线性扫描伏安法研究了阿奇霉素在多壁碳纳米管修饰玻碳电极上的电化学行为,建立了一种直接测定阿奇霉素的电化学分析方法。结果表明,与裸玻碳电极相比,多壁碳纳米管修饰电极能显著提高阿奇霉素的氧化峰电流,阿奇霉素的电极过程完全不可逆,存在典型的吸附特性。在优化的实验条件下,氧化峰电流与阿奇霉素浓度在3.0×10-7~2.5×10-5 mol/L和2.5×10-5~5.0×10-4 mol/L范围内呈现良好的线性关系,检出限为1.0×10-7 mol/L。 相似文献
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报道了水合肼在碳纳米管修饰电极上的电化学行为以及水合肼测定的新方法。与裸玻碳电极相比,多壁碳纳米管修饰玻碳电极使水合肼的氧化峰电流显著提高,同时氧化过电位降低,测定灵敏度大为提高。优化了底液、pH、修饰剂量等测定条件。在最佳条件下,该修饰电极测定水合肼的线性范围为2.9×10-8~9.8×10-4mol/L,线性相关系数为-0.9945,检出限为1.0×10-9mol/L。对1.0×10-4mol/L的水合肼平行测定10次的相对标准偏差为4.4%。此方法已用于模拟水样中水合肼的测定。 相似文献
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A very stable electroactive film of catechin was electrochemically deposited on the surface of activated glassy carbon electrode.
The electrochemical behavior of catechin modified glassy carbon electrode (CMGCE) was extensively studied using cyclic voltammetry.
The properties of the electrodeposited films, during preparation under different conditions, and the stability of the deposited
film were examined. The charge transfer coefficient (α) and charge transfer rate constant (k
s) for catechin deposited film were calculated. It was found that the modified electrode exhibited excellent electrocatalytic
activity toward hydrazine oxidation and it also showed a very large decrease in the overpotential for the oxidation of hydrazine.
The CMGCE was employed to study electrocatalytic oxidation of hydrazine using cyclic voltammetry, rotating disk voltammetry,
chronoamperometry, amperometry and square-wave voltammetry as diagnostic techniques. The catalytic rate constant of the modified
electrode for the oxidation of hydrazine was determined by cyclic voltammetry, chronoamperometry and rotating disk voltammetry
and was found to be around 10−3 cm s−1 . In the used different voltammetric methods, the plot of the electrocatalytic current versus hydrazine concentration is
constituted of two linear segments with different ranges of hydrazine concentration. Furthermore, amperometry in stirred solution
exhibits a detection limit of 0.165 μM and the precision of 4.7% for replicate measurements of 40.0 μM solution of hydrazine. 相似文献
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Ferricyanide immobilized within organically modified MCM-41; application for electrocatalytic reduction of hydrogen peroxide 总被引:1,自引:0,他引:1
Reza Ojani Jahan-Bakhsh Raoof Shahla Fathi 《Journal of Solid State Electrochemistry》2009,13(6):837-842
Carbon paste electrode modified with aminated Mobil Catalytic Material Number 41 (MCM-41) was prepared and used for immobilization
of K3[Fe(CN)6] in acidic medium, and then electrochemical behavior of modified electrode containing ferricyanide was studied in detail,
including pH-dependence and scan rate effect. Cyclic voltammetry studies showed that the electrode reaction is a surface-controlled
process at the scan rate range from 5 to 60 mV s−1. Also, the electrocatalytic behavior of modified electrode toward the reduction of H2O2 is reported and the effect of pH on catalytic peak current was discussed. According to experimental results, with increasing
solution pH, the catalytic effect of this modified electrode is decreased. Catalytic reduction current of H2O2 increases linearly with its concentration. It has been demonstrated that ferricyanide immobilized on the aminated MCM-41
is a stable catalyst for the electrocatalytic reduction of H2O2. 相似文献
15.
In the present work, the oxidative electrochemistry of nitrite on the poly(3,4-ethylenedioxythiophene)/iron phthalocyanine/multi-wall carbon nanotubes-(PEDOT/FePc/MWCNT) modified screen-printed carbon electrodes (SPCE) has been investigated. The parameters, such as overpotential, current density and rate constant at PEDOT/FePc/MWCNT-modified SPCE, were compared with an un-modified, FePc-, and FePc/MWCNT-modified SPCE for electro-oxidation of nitrite. As compared with the un-modified SPCE, an increase in the anodic peak current density (Jpa) (∼100%) along with a decrease in the anodic peak potential (Epa) of ∼150 mV for electro-oxidation of nitrite at the FePc-modified SPCE was observed. When an under-layer of MWCNT was introduced onto FePc-modified SPCE, denoted as FePc/MWCNT-modified SPCE, and the number of FePc/MWCNT bilayer was optimized, the heterogeneous electron transfer rate constant (k) at FePc/MWCNT-modified SPCE was enhanced about 7.8 times as compared with that at FePc-modified SPCE. Moreover, as a layer of PEDOT film was electrodeposited onto the FePc/MWCNT-modified SPCE, denoted as PEDOT/FePc/MWCNT-modified SPCE, a significant increase in current response along with a remarkable decrease in Epa were noticed. This can be attributed to the pre-concentration effect induced by the electrostatic interaction between the negatively charged nitrite and oxidized PEDOT film. On the whole, the PEDOT/FePc/MWCNT-modified SPCE greatly reduces the overpotential of ∼330 mV along with 3.5 times enhanced the peak current density for the electro-oxidation of nitrite as compared with un-modified SPCE. The sensitivity and limit of detection (S/N = 3) for the PEDOT/FePc/MWCNT-modified SPCE were found to be as 638 mA cm−2 M−1 and 71 nM, respectively. Notably, PEDOT/FePc/MWCNT-modified SPCE has a lower sensing potential than compared to several other modified electrodes. The developed sensor was also applied for the determination of nitrite in tap water sample. 相似文献
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聚吡咯/多壁碳纳米管修饰电极对多巴胺的测定 总被引:5,自引:3,他引:5
制备了聚吡咯/多壁碳纳米管(PPy/MWNT)复合膜修饰电极。研究了神经递质多巴胺(DA)在该修饰电极上的电化学行为。实验表明,PPy/MWNT复合膜修饰电极对DA的电催化作用优于PPy修饰电极。在pH=4.10的0.2mol/L醋酸-醋酸钠缓冲溶液中,DA在该修饰电极上的CV曲线于0.31V和0.28V处出现一对灵敏的氧化还原峰,峰电位差△Ep比裸玻碳电极降低58mV,比PPy修饰电极降低28mV,峰电流显著增加。氧化峰电流ipa与DA浓度在1.0×10-4~7.8×10-8mol/L范围内呈良好的线性关系,线性回归方程为ip(μA)=0.2512 1.2300C(×10-5mol/L),相关系数r=0.9992,检出限为3.9×10-8mol/L。常见物质对DA的检测无干扰,DA注射液样品检测回收率为94%~104%。 相似文献
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In this work, ionic liquid (IL, i.e. 1-hydroxyethyl-3-methylimidazolium tetrafluoroborate), carboxyl multiwall carbon nanotubes (MWCNTs) and reduced graphene oxide (rGO) were used to prepare three-dimensional porous material (MWCNTs-rGO-IL) by one-step self-assembly, then it was co-electrodeposited with polyaniline (PANI) on stainless steel wires by cyclic voltammetry. The resulting coating (PANI-MWCNTs-rGO-IL) was characterized by using FT-IR and scanning electron microscopy etc, and it showed porous structure and had high thermal stability. Furthermore, it was found to be very suitable for the headspace solid-phase microextraction of alcohols (i.e. octanol, nonanol, geraniol, decanol, undecanol and dodecanol). By coupling with gas chromatography, wide linear ranges and low limits of detection (i.e. 2.2–28.3 ng L−1) were obtained for the alcohols. The coating also presented good repeatability and reproducibility; the relative standard deviations for intra-fiber and fiber-to-fiber were less than 5.6% (n = 5) and 7.0% (n = 5) respectively. In addition, the proposed method was successfully applied to the determination of alcohols in tea drinks, and the recoveries for standards added were 85.6–114%. 相似文献
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Qilin Cheng Vladimir Pavlinek Ying He Chunzhong Li Petr Saha 《Colloid and polymer science》2009,287(4):435-441
In this paper, one-dimensional polyaniline/titanate (PANI/TN) composite nanotubes were synthesized by in situ chemical oxidative
polymerization directed by block copolymer. These novel nanocomposite particles were used as a dispersed phase in electrorheological
(ER) fluids, and the ER properties were investigated under both steady and dynamic shear. It was found that the ER activity
of PANI/TN fluids varied with the ratio of aniline to titanate, and the PANI/TN suspensions showed a higher ER effect than
that made by sphere-like PANI/TiO2 nanoparticles. These observations were well interpreted by their dielectric spectra analysis; a larger dielectric loss enhancement
and a faster rate of interfacial polarization were responsible for a higher ER activity of nanotubular PANI/TN-based fluids. 相似文献
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Hadi BEITOLLAHI Alireza MOHADESI Farzaneh GHORBANI Hassan KARIMI MALEH Mehdi BAGHAYERI Rahman HOSSEINZADEH 《催化学报》2013,34(7):1333-1338
A benzoylferrocene modified multi‐wall carbon nanotube paste electrode for the measurement of methionine (MET) concentration is described. MET electrochemical response characteristics of the modified electrode in a phosphate buffer solution of pH 7.0 were investigated by cyclic voltammetry, square wave voltammetry, and chronoamperometry. Under optimized conditions, the square wave voltammetric peak current of MET increased linearly with MET concentration in the range of 1.0×107 to 2.0×104 mol/L. The detection limit was 58.0 nmol/L MET. The diffusion coefficient (D=5.62×106cm2/s) and electron transfer coefficient (α=0.4) for MET oxidation were also determined. The sensor was successfully applied for the measurement of MET concentration in human urine. 相似文献