Electrochemical methods capacitance effects

The use of conventional electrochemical methods to study the effect of metal adatoms on the electrochemical oxidation of an organic adsorbate may be in some cases of limited value. Very often, in the potential region of interest the current due to the oxidation of an organic residue is masked by faradaic or capacitive responses of the cocatalyst itself. The use of on-line mass spectroscopy overcomes this problem by allowing the observation of the mass signal-potential response for the C02 produced during the oxidation of the adsorbed organic residue. 

The popularity of the cychc voltammetry (CV) technique has led to its extensive study and numerous simple criteria are available for immediate anal-j sis of electrochemical systems from the shape, position and time-behaviour of the experimental voltammograms [1, 2], For example, a quick inspection of the cyclic voltammograms offers information about the diffusive or adsorptive nature of the electrode process, its kinetic and thermodynamic parameters, as well as the existence and characteristics of coupled homogeneous chemical reactions [2]. This electrochemical method is also very useful for the evaluation of the magnitude of imdesirable effects such as those derived from ohmic drop or double-layer capacitance. Accordingly, cyclic voltammetry is frequently used for the analysis of electroactive species and surfaces, and for the determination of reaction mechanisms and rate constants. 

Liang, C. H., and C. S. Hwang. 2010. Effects of temperatures and cations of electrolyte on the capacitive characteristics of the manganese oxide deposited by hydrothermal electrochemical method. Journal of Alloys and Compounds 500 102-107. 

Aureli M, Porfiri M (2012) Effect of electrode surface roughness on the electrical impedance of ionic polymer-metal composites. Smart Mater Struct 21 105030 Aureli M, Lin W, Porfiri M (2009) On the capacitance-boost of ionic polymer metal composites due to electroless plating theory and experiments. I Appl Phys 105 104911 Bard AJ, Falkner LF (2001) Electrochemical methods fundamentals and applications, 2nd edn. Wiley, New York... 

Electrochemical analytical techniques are a class of titration methods which in turn can be subdivided into potentiometric titrations using ion-selective electrodes and polarographic methods. Polarographic methods are based on the suppression of the overpotential associated with oxygen or other species in the polarographic cell caused by surfactants or on the effect of surfactants on the capacitance of the electrode. One example of this latter case is the method based on the interference of anionic surfactants with cationic surfactants, or vice versa, on the capacitance of a mercury drop electrode. This interference can be used in the one-phase titration of sulfates without indicator to determine the endpoint... 

Adsorption phenomena have been studied by means of virtually every electrochemical technique, including recently developed spectroelectrochemical methods. Electrocapillary methods and measurements of double-layer capacitance have played a central role in the understanding of adsorption. AC studies have also been very useful and are very sensitive to adsorption effects. More recently, chronocoulometry (Chap. 3, Sec. II.C) has been applied effectively to the measurement of quantities of adsorbed electroactive species. The interested reader is referred to the sections that deal with these techniques for more detailed information. 

Wang et al. synthesized Graphene/SnO /polypyrrole ternary nanocomposites by one-pot synthesis method and obtained specific capacitance of 616 F/g. They claimed that the excellent electrochemical performance was due to the synergistic effect among the three components [46]. 

We will show that the ILIT method eliminates some of the problems associated with an electrical perturbation and, not surprisingly, creates new, interesting, and challenging problems. Improved electronics developed at the time of the termination of this program, coupled with picosecond or subpicosecond laser pulses, should, in principle, allow the ILIT method to probe interfacial relaxations of the order of 1 ns or less (our published work has used a slower system with a response function of the order of 15 ns). Of course, really dramatic improvement in response time will be achieved only with a pump-probe approach. Nevertheless, even at its present stage of development, ILIT effects significant improvement in time resolution over methods using conventional electrochemical perturbations where the time resolution is limited by solution resistance and interfacial capacitance (see Ref. 41) ... 

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