In this note, several electrochemical investigations are performed in order to characterized the photovoltaic cell, such as linear polarization (LP) or electrochemical impedance spectroscopy (EIS).

To obtain significant EIS plots, without noise or trouble, experimental parameters should be chosen carefully. Then user has to pay attention of the definition of each parameter and to test the effect of each one on the result. Moreover, each electrochemistry software is conceived differently and user has to adapt parameters depending on the software. The aim of this note is to help the user to obtain good experimental results with EC-Lab€ software. For this a detailed description of some key points (connection, cable length, experimental parameters, …) is given in the following.

In this note, corrosion process of the metallic rod in a concrete block is investigated. Realkalisation (electroysis in basic media) is performed and benefits of the treatment is checked by Cyclic Potentiodynamic Polarization (CPP).

All electrochemical processes take place at the electrode/electrolyte interface, i. e. the electrical double layer (Fig. 1). Different models of this layer were stated by Helmholtz, Gouy-Chapman, Stern or Grahame. The structure of the double layer is similar to an electrical condensateur constituted by two charged area separated by a dielectric. The dielectric thickness corresponds to the ionic radius, i. e. 50 nm. In this note, the electrical double layer of iron electrode in acidic condition is investigated. In this purpose, two techniques are used to determine the value of the capacitance: the Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV).

当你需要直接进样快速分析苯系物（苯，甲苯，乙苯，二甲苯）时可选用DPS公司的苯系物快速分析仪，样品可采用手动直接进样或使用110位液体自动进样器进样。为了分析水中低浓度范围（ppb）的苯系物可以选择内置吹扫捕集器，模块化的吹扫捕集器可安装在气相色谱仪柱温箱右侧的捕集模块部位，不需要庞大的加热转换线。在部分领域分析土壤气体中苯系物首选的方法安装一个吸附管，根据这个应用我们专门设计出土壤中苯系物气体分析仪，为了方便起见，我们还在系统右侧内置了气体浓缩器，及包括一个带流量精确控制和重现性好的电动真空泵。另外，还有一部分领域的土壤气体是放在样品瓶内进行加热，然后将顶空样品进入到气相色谱仪内，我们根据这种方法也专门设计了土壤气体顶空气相色谱分析仪，你还可以选择40位顶空气体自动进样器进行自动进样。为了你每日的分析节约成本所有苯系物分析仪都采用一体化设计。为了获得更多的利润，吸引更多的客户和保护您的企业，建议您选用DPS公司模组化苯系物气相色谱仪。

生物柴油是替代石化柴油燃料的一种可再生的燃料。这种可生物降解、无毒性的生物柴油由豆油、蔬菜油、再循环冷却油及动物脂肪制成。由蔬菜油和动物脂肪制成的生物柴油与石油性能相似，但是它燃烧更完全并降低排放。高含量的自由基氨基乙酸和总氨基乙酸将导致沉积及差的发动性能。因此，氨基乙酸含量是生物柴油燃料质量的指标，为了客户方便，DPS生产了生物柴油气相色谱分析仪帮助客户确认自由基氨基乙酸和总氨基乙酸的含量，DPS配置了标准的冷柱上进样口、保护柱、分析柱和高灵敏度FID检测器。DPS公司的每个气相色谱仪均配有快速加热和快速冷却的柱温箱，可大量地增加样品通量。如果在仪器上安装一个110位液体自动进样器便于客户昼夜不懂地运行此分析系统。整体的生物柴油气体分析仪系统是一款外观小、重量轻、便于放置任何场合的仪器。所有的DPS气相色谱仪都是模块化的，便于扩展、升级以及方便维修。

当需要检测低浓度的气体时，推荐您使用DPS公司生产的高灵敏度气体分析仪。美国DPS气相色谱仪可根据您的分析要求，通过调整检测器灵敏度的动态范围，以满足从超低浓度的气体分析到常量气体分析。

　摘要　介绍一个可用于化学系本科生开设的综合化学实验。该实验构思源于手性对二甲氨 基苯甲醛缩氨基苯硫脲(DMB)的绝对不对称合成。学生可通过实验发现、观察和探究手性对称性 破缺的奇妙现象,并掌握标题化合物组成、结构和手性性质的各种表征方法,特别是固体圆二色 (CD)光谱方法。

摘要结合课题组近期的相关研究, 对固体CD 光谱在手性配合物研究中的应用, 特别是手性样品固体CD 光 谱的测试方法进行了概述, 通过对四对手性席夫碱M(II) (M= Ni、Cu)配合物的固体和溶液CD 光谱进行比较研 究,发现配合物的手性构型在固液相中保持一致, 但其固液CD光谱之间存在不同程度的差异, 可能是由于相应 配合物在固体和溶液相中的四面体扭曲或构象的微妙不同所致.

It could be sometimes useful to substitute a RQ circuit by a RC circuit.

EIS measurements are sometimes very long especially at low frequencies. It can be an important issue for systems varying with time. To overcome this problem, it could be useful to work in multisine impedance measurement mode. This measurement mode consists in exciting and measuring various frequencies in the same time contrary to the single sine measurement mode.

It is sometimes useful to automate some measurements. With EC-Lab and EC-Lab Express, it is possible to automatically perform successive impedance measurements during a potential sweep with the SPEIS (Staircase Potentio Electrochemical Impedance)technique. This technique allows the user to do in the same experiment successive potential steps with an electrochemical impedance spectroscopy measurement on each. For each experiment, the user defines the conditions. One of the applications of this technique is to study electrochemical reaction kinetics along steady-state curves. Note that the same process can be used in galvanostatic mode with the SGEIS technique.

Several conditions are required to measure the electrochemical impedance of a system. Its behaviour has to be linear, invariant vs. time and the system should be in a steady state. Indeed, if the steady state is not reached by the system, the electrochemical impedance signal used to calculate the Fourier Transform is not periodic. Moreover the presence of transient period due to the excitation step implies into the result spectrum a contribution to the response of the imposed sinusoid.

Electrochemical generators such as primary and secondary batteries, fuel cells(FCs) and supercapacities are often made up of several elements connected in series. It is possible to connect dozens of these elements on FC stacks. The measure of the potential difference on each cell allows the user to detect if there is a dysfunction on a cell but does not give the reason why. On the other hand, impedance measurements on the different cells under a constant load, can be useful, for example, to determine the internal resistance value or if there is a problem with the gas distribution in the stack.

Using the Kramers-Kronig(KK)transforms, the real part of a transfer function can be calculated, for a causal, stable, linear, time invariant and finite system when f→0 and f→∞, when the change in its imaginary part, as a function of the frequency, is known. At the opposite, the imaginary part of a transfer function can be calculated when the evolution of its real part is known.

It has long been known that different electrical circuits can explain EIS data in an equivalent manner. that is, they exhibit identical impedance for all frequencies. Ec-Lab software is provided with a powerful tool for EIS data analysis called Zfit. This tool can perform electrical circuit identification with EIS experimental data files obtained either with Bio-Logic potentiostats/galvanostat or with other systems on the market. In fact, EC-Lab software can import ASCII text files generated by other electrochemical stations and perform efficient EIS fits. The user can choose between two different minimization algorithms. Simplex and Levenberg/Marquardt to achieve the best electrical element values.

The evolution of the research directions through the nano size and complex systems leads the researchers to use more and more efficient analytical methods: Now an analytical technique can not be used alone any more in a lab: It may not be sufficient to identify and describe a whole system. Rspecially for bioelectrochemical systems it becomes essential to have more than one analytical technique to understand the reaction mechanisms.

With regard to the increasing necessity for researcher to have discriminating methods. Electrochemical techniques could not easily be used alone anymore. Instruments for electrochemical studies must be able to be connected to other external instruments. Coupled with other analytical methods. Electrochemistry becomes a powerful characterizing method. For example, polypyrrol films have often and widely been studied by an electrochemical way especially the electropolymerisation process. The only use of electrochemistry is not now sufficient to explain the whole electropolymerisation process. One can easily understand the interest of coupled method in studying species with spectroscopic properties. Electrochemistry coupled with spectroscopic methods is now an usual combination of discriminating techniques for polypyrrol study. Coupling methods often result in technical and assembling problems to synchronize the electrochemical experiment and the external measurement and to record external variables. These are the main user''s needs.

The state of surface of an electrode can be very important depending on the experiment carried out. It should always be as neat as possible to avoid parasite reactions. It should also be, according to the electrode°Osgeometry, as smooth as possible. For example, in the case of a planar electrode, the surface should be as plane as possible on a microscopic scale. In the proper conditions, characteristic values can be determined such as the number of adsorption sites per surface unit for a given material. The aim of this tutorial is to show to the user how to determine the active surface of an electrode from a voltammetric curve giving I vs. E .

The corrosion current is a typical corrosion value which can be related, for example, to the corrosion rate. The information obtained from both values is necessary when studying the corrosion state of a given system. The aim of this tutorial is to show to the user how to determine the corrosion current using simple graphic tools on EC-Lab linked to the Tafel equation: Tafel fit and R fit.

Electrochemical Impedance Spectroscopy (EIS) is an interesting tool devoted to the study of linear systems. However, electrochemical systems are often non linear. Before explaining the different ways to deal with this issue, we will point out the main differences between linear and non-linear systems.

IMPEDANCE OR ADMITTANCE NYQUIST''S DIAGRAMS IMPEDANCE OR ADMITTANCE BODE DIAGRAMS IMPEDANCE OR ADMITTANCE BLACK DIAGRAM

The hydrodynamic regime is ensured with a rotating electrode laid by a rotating power unit. The working electrode in the electrochemical cell is typically made either with a single disk or with a rotating ring-disk electrode. The rotating ring-disk electrode was developed by Frumkin and Nekrasov in 1959. The theoretical part was definitely achieved in 1971 [1]. The applications are numerous in the fields of electrochemical analysis, especially in reaction mechanism study. The rotating electrode is often used for the detection of short life intermediate species.

The Constant Power Protocol has been designed to study the discharge (eventually the charge) of a battery or a cell (made of intercalation compounds) at successive constant power. The constant power control is made into holding the power (i.e. the factor E*I) to a constant value. During the discharge, the cell potential decreases. In order to hold a constant power, the current is adjusted and will increase. This can be shown on the following figure.

From biological cells analysis to fuel cells tests, from coatings to cement paste quality control, the electrochemical impedance spectroscopy (EIS) has become a powerful tool in the vast environment of electrochemistry. As a nonintrusive and highly sensitive technique, EIS requires basic precautions, often overlooked, to achieve error free data. This document aims to highlight the nature of the error sources placed outside the electrochemical cell and their effects in the study of the electrochemical systems with the EIS technique with an accent on high and low impedance cells. General conditions for accurate measurements related to the sample linearity, causality, time independence and stability are beyond the scope of this note.

As the vast majority of research instruments, potentiostats are seldom used in trivial experimental conditions. But potentiostats are not only facing the unusual nature of the research activity, but also the great diversity of electrochemical systems and experiments. Even more, due to their nature, the electrochemical experiments evolve over extremely large ranges of values of the significant parameters. In corrosion applications, for example, recording the current over 5 or 6 current ranges in the same experiment is very common. It is not hard to imagine that, in such a demanding environment, potentiostats are often pushed to their limits and used in situations that may compromise their performance. There are always times when potentiostats are not functioning as expected. Ringing or oscillations, for example, are signs that a potentiostat has difficulties to maintain, or has even lost the control of the cell potential.

This aim of this paper is to describe an application of the GCPL 4 protocol in the field of battery testing. This protocol is available with EC-lab software and can be used with all our instruments. This galvanostatic cycling protocol has a timing different from the previous GCPL protocol, in the way that the total duration of every sequence is defined, independently from the fact that at a given time during the step the maximum potential can be reach and the instrument turns from the initial galvanostatic mode to a constant potential one.

Basically a continuous dependence of the potential vs. composition corresponds to a solid-solution single-phase domain whereas a potential plateau corresponds to a two-phase domain. Other properties of interest, particularly in view of possible applications as active electrode in a battery are the potential window of electrochemical stability, kinetics and reversibility of the intercalation process.

The basic characteristic of an electroactive intercalation compound is the thermodynamic voltage-composition relation, that corresponds to the equilibrium phase diagram of the system. See for example Armand (1980) for detailed description of the various behavior that can be encountered, which depends on the changes in electronic and structural properties upon intercalation/deintercalation. Basically a continuous dependence of the potential vs. composition corresponds to a solid-solution single-phase domain whereas a potential plateau corresponds to a two-phase domain. Other properties of interest, particularly in view of possible applications as active electrode in a battery are the potential window of electrochemical stability, kinetics and reversibility of the intercalation process.

单糖分离 单糖可用正丁醇／乙醇／水两相系统分离．用水下相洗脱时，蔗糖和岩藻糖两种糖从蔗糖、岩藻糖、葡萄糖三糖混合物中分离出来，而使用上相有机相时，三种糖就分离开了。