共查询到20条相似文献,搜索用时 15 毫秒
1.
V. V. Pototskaya N. E. Evtushenko O. I. Gichan 《Russian Journal of Electrochemistry》2004,40(4):424-431
A theoretical model for the generalized finite adsorption impedance of a rough electrode is offered. A complex function of the roughness of the electrode surface is introduced and its frequency dependence is studied. The frequency characteristics of constituents of the adsorption impedance are shown to depend on the electrode roughness and the diffusion layer thickness. The frequency dependences of the phase angle and impedance components are found to considerably differ from the Frumkin–Melik-Gaikazyan result for an ideal smooth electrode. 相似文献
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《Analytical letters》2012,45(4):341-347
Abstract The influence of viscosity on diffusion at the stationary electrode is studied. Relations between the maximum electrolysis time attainable without any disturbance by natural convection, the thickness of the diffusion layer and solution viscosity are presented and discussed in the case of constant current electrolysis at shielded electrodes. A re-examination of data existing in literature is made. 相似文献
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《Electroanalysis》2003,15(4):312-318
The adsorption of TBP on Hg electrode from aqueous NaClO4 media has been studied using differential capacity and chronocoulometric measurements. TBP adsorbs in two steps, the first corresponding to a flat and second to a perpendicular orientation. Both orientations were observed in the entire investigated potential range. The maximal measured surface concentration (Γmax) of TBP reaches a value of 1.55×10?10 mol cm?2, which corresponds to the theoretical value for densely packed molecules in perpendicular orientation. Γ value of the first isotherm step plateau is about 7 to 15% smaller than Γmax and decreases strongly at potentials more negative than ?0.9 V due to the repelling of negative charges between the electrode and the phosphate group. The standard Gibbs energy of adsorption was found to reach the value of ?34 kJ mol?1. 相似文献
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《Electroanalysis》2006,18(2):127-130
The voltammetric behavior of 2‐methyl‐4,6‐dinitrophenol was investigated by differential pulse voltammetry (DPV) at a nontoxic mercury meniscus‐modified silver solid amalgam electrode (m‐AgSAE). Conditions have been found for its determination by DPV at m‐AgSAE in the concentration range of 0.2 to 1 μmol L?1. 相似文献
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Farid Khan 《中国化学会会志》2007,54(3):673-679
Charge transfer reactions between a dropping mercury electrode and a [Mn‐antibiotics‐cephalothin] system were studied at pH = 7.30 ± 0.01, μ = 1.0 MNaClO4 at 298 K. The antibiotics were doxycycline, chlortetracycline, oxytetracycline, tetracycline, minocycline, amoxicillin and chloramphenicol used as primary ligands and cephalothin as secondary ligand formed 1:1:1, 1:1:2 and 1:2:1 complexes with Zn2. Electrode kinetics was discussed on the basis of kinetic parameters viz. transfer coefficient (α), degree of irreversibility (λ), diffusion coefficient (D) and rate constant (k). The values of α varied from 0.40 to 0.57 (0.50) confirm that ‘transition state’ behaves between reactant and product response to applied potential and it lies always between d.m.e. and solution interface. A small variation in potential affects the rate and rate constant greatly. 相似文献
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《Electroanalysis》2003,15(22):1778-1781
The voltammetric behavior of N,N‐dimethyl‐4‐amino‐2′‐carboxyazobenzene was investigated by differential pulse voltammetry (DPV) at a mercury meniscus‐modified silver solid amalgam electrode (m‐AgSAE). Conditions have been found for its determination by DPV at m‐AgSAE in the concentration range of 0.4 to 15 μmol L?1. 相似文献
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Azadeh Kiani Ali Ghaffarinejad Seyed Abolfazl Seyedsadjadi Atiyeh Mansouri 《Electroanalysis》2020,32(2):281-290
In this study, an available and inexpensive graphite substrate, was easily modified with Ni/Cr nanoparticles via electrodeposition technique in a very short time (3 min) and used as an electrocatalyst for glucose oxidation in alkaline solution. Graphite electrode modified with Ni/Cr nanoparticles demonstrated an outstanding electrocatalytic performance to glucose oxidation in comparison to examined Ni‐based electrodes or even different materials in other reports. It is noteworthy to mention that adding a little Cr led to a synergistic effect with Ni; accordingly, the presence of Cr not only resulted in a greater adsorption of glucose molecules by chromium oxide but also boosted conductivity of the nickel oxide because of the enhancement of Ni(III) amount. The electrochemical studies were performed by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). The morphology and structure of catalyst layer was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) and energy dispersive x‐ray spectroscopy (EDS). The linear range of the electrode by cyclic voltammetry was between 2–31 mM with a high sensitivity of 2094 μA cm?2 mM?1. The repeatability and reproducibility of the proposed electrode was examined in glucose solution which were 0.3 % and 4.7 %, respectively. According to the low cost, ease and fast preparation, good repeatability and high sensitivity, this electrode can be a good candidate for nonenzymatic glucose oxidation. 相似文献
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用XPS、DRS及Mossbauer谱对水热处理改性的FeZSM-5中Fe(Ⅲ)的化学状态进行了研究,并定量地考察了水热处理时间对骨架铁含量的影响,比较了不同水热处理时间及不同平衡阳离子交换的FeZSM-5上乙苯的吸附及扩散性质。水热处理将使骨架铁从骨架析出,但析出的骨架铁并不阻塞孔道,而是高分散在分子筛的表面上,乙苯的吸附量随水热处理时间增加而增大。阳离子交换的FeZSM-5上乙苯的扩散系数及吸附量均按H、Li、Na、K离子半径增大的顺序递减。乙苯的氧化脱氢活性主要取决于Fe(Ⅲ)活性中心的性质,也与乙苯的吸附量及扩散系数有关。 相似文献
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《Electroanalysis》2006,18(6):605-612
This paper reports the construction, characterization and use of copper solid amalgam electrode in the study of the electrochemical behavior of atrazine and ametryne herbicides by square‐wave voltammetry. This study was used as basis for the development of sensitive analytical methods for the determination of these herbicides in natural water, avoiding the use of mercury, by means of a solid electrode that presents high sensitivity and minimizes any environment contamination with mercury residues. The experimental and voltammetric conditions were evaluated and the results showed a reduction peak for atrazine at ?0.98 and at ?1.1 V vs. Ag/AgCl 3.0 mol L?1 for ametryne, both with characteristic of an irreversible electrode reaction in an electrochemical diffusion controlled process, involving two electrons for each herbicide reduction. Based on voltammetric studies, it has been demonstrated that the most possible mechanism for the reduction of herbicides involved reduction of bond carbon‐chloride for atrazine and the reduction of bond carbon–SCH3 for ametryne. The detection limit of herbicides obtained in pure water (laboratory samples) was shown to be lower than the maximum limit of residue established for natural water by the Brazilian Environmental Agency, demonstrating that this methodology is very suitable for determining any contamination by atrazine and ametryne residues in different samples, proving a good substitute for mercury electrodes. 相似文献
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Luis Arzondo J. Pablo Tomba Jos M. Carella Jos M. Pastor 《Macromolecular rapid communications》2005,26(8):632-636
Summary: We explored the diffusion mechanisms in a series of liquid/glassy polymer interphases. The diffusion experiments were performed in a unique way: the temperature range studied encompassed the glass transition temperature (Tg) of the glassy matrices. We observed that the diffusion behavior of the liquid polymer was remarkably continuous when passing through the matrix Tg, and that the diffusion modes at the liquid/glassy interphases were very similar to those observed in liquid/liquid polymer diffusion.
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XiaoFengWANG DongPingZHAN YunYiFU RuHUANG XingZHANG YuanHuaSHAO 《中国化学快报》2004,15(12):1480-1482
The spillover phenomenon is observed on the platinum (Pt) disk electrode modified by multi-wall carbon nanotubes (MWNTs). The rate of the spillover of oxygen-containing species produced on Pt surface to and from MWNTs is fast. However for hydrogen-adatoms, the spillover is very weak. The selective spillover on the Pt/MWNTs electrode may provide a novel way to design catalysts. 相似文献
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用电化学和现场红外反射吸收光谱方法研究了Pt电极上吡啶的吸附取向。结果表明,在-0.80~0.80 V(vs SCE)范围内皆存在吡啶吸附,在较负电势下(约-0.80~-0.20 V),吡啶环可能以2种方式吸附于电极表面上,随电势变正(约-0.20~0.80V)由垂直取向向平躺取向转变,该平躺吸附降低了电极表面及其附近水分子结构的有序性。 相似文献
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《Electroanalysis》2017,29(3):756-764
Direct electro‐oxidation of famotidine at different graphitic carbon‐based electrode materials was evaluated. These materials included conventional electrodes of edge‐plane pyrolytic graphite, basal‐plane pyrolytic graphite, carbon paste, and glassy carbon as well as nano‐structured carbon‐based materials such as pyrolytic carbon film, carbon nanotube, and nano‐graphene. Raman spectroscopy and scanning electron microscopy were employed to analyze their structural and morphological features. It was found that the pyrolytic carbon film electrode, after a simple and fast anodic activation, shows superior electroanalytical performance. The method was successfully applied for the electroanalytical determination of famotidine in tablet dosage forms and urine samples. 相似文献
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Voltammetric Determination of 8‐Nitroquinoline Using a Silver Solid Electrode and Its Application to Model Samples of Drinking and River Water 下载免费PDF全文
This work is focused on the application of a silver solid electrode (AgE) for the development of modern voltammetric methods for the determination of submicromolar concentrations of biologically active compounds present in the environment. 8‐Nitroquinoline (8‐NQ), a well‐known chemical carcinogen, was chosen as a model substance. Differential pulse voltammetry (DPV) was used to study electrochemical behavior of 8‐NQ in different aqueous matrices. The following optimal conditions for determination of 8‐NQ in the concentration ranges from 2 to 100 µmol L?1 were used: Britton? Robinson (BR) buffer of pH 3.0, the regeneration potentials cycles (Ein=?1000 mV, Efin=?100 mV) and constant cleaning potential ?2000 mV. Practical applicability of AgE for the determination of micromolar concentrations of 8‐NQ was verified on model samples of drinking and river water. 相似文献
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林仲华 《高等学校化学学报》1990,11(8):903-905
电化学调制紫外可见反射光谱技术可用来测定金属电极上吸附物种的取向和吸附物种与金属表面间的相互作用,金属Au与已研究过的Pb、In和Pt[1~]具有不同形式的能带结构,吸附物种与电极表面间相互作用的电位依赖性可能不同。本文测定了吡啶分子吸附时Au电极的反射差谱,并试图从能带模型角度探讨吡啶分子与Au电极表面原子间的相互作用。 相似文献
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《Analytical letters》2012,45(15):2339-2363
Abstract Electrodes based on amalgam materials were re-introduced in electroanalytical chemistry in the year 2000, partially as reaction to unsubstantiated public fears of liquid mercury. In this publication, the voltammetric behavior of 1-nitronaphthalene and 2-nitronaphthalene was investigated at a mercury meniscus-modified silver solid amalgam electrode. The reduction mechanism in mixed neutral buffer-methanol medium includes the four-electron reduction to hydroxylaminoderivative followed by a two-electron reduction to the amine in acidic medium, similarly to mercury electrodes. In alkaline media, both compounds show the splitting of the main four-electron reduction peak typical for mercury electrodes in two new ones, the first one corresponding to a one electron reduction of the nitroderivative to the nitro radical anion, which was confirmed by microcoulometry. Using optimized conditions (differential pulse voltammetry, Britton-Robinson buffer pH 7.0 – methanol (9:1) medium) the calibration dependences are linear in the range of 2·10?7 (4·10?7) to 1·10?4 mol L?1 for 1-nitronaphthalene (2-nitronaphthalene). After preconcentration of the analytes from drinking and river water samples using solid phase extraction the limit of determination was lowered to ~3·10?8 mol L?1. 相似文献