好资料[电化学常见问题问答],[例]其中一个问题: What is cyclic voltammetry, and why is it so commonly used? In a cyclic voltammetry experiment, as in other controlled potential experiments, a potential is applied to the system, and the faradaic current response is measured (a faradaic current is the current due to a redox reaction). The current response over a range of potentials (a potential window) is measured, starting at an initial value and varying the potential in a linear manner up to a pre-defined limiting value. At this potential (often referred to as a switching potential), the direction of the potential scan is reversed, and the same potential window is scanned in the opposite direction (hence the term cyclic). This means that, for example, species formed by oxidation on the first (forward) scan can be reduced on the second (reverse) scan. This technique is commonly used, since it provides an fast and simple method for initial characterization of a redox-active system. In addition to providing an estimate of the redox potential, it can also provide information about the rate of electron transfer between the electrode and the analyte, and the stability of the analyte in the electrolyzed oxidation states (e.g., do they undergo any chemical reactions). What is potentiostatic control of an electrode? A control voltage is fed into the control input CI. This control voltage forces a current through the counter electrode exactly as high as to achieve the wanted potential difference between working electrode and reference electrode. The control voltage may be produced by the internal potential control source of the potentiostat, or by an external signal generator, e.g. a ramp generator or a sine wave generator. While for a constant potential the internal potential control source is sufficient, time-dependent signals are to be fed from external sources (except our scanning potentiostats that also have built-in voltage scanners). Figure: Scheme of the potentiostatic control loop. RE Reference electrode, WE working electrode, CE counter electrode, CI control input Why are the peaks in a cyclic voltammogram asymmetric (tailed)? 电化学常见问题问答
电化学常见问题问答
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