Alternating current AC impedance

One of the most powerful methods for the investigation of electrochemical reactions is the use of alternating current (AC) impedance techniques. In order to understand the basis of this approach, however, it is helpful first to consider some simple electronic analogues which mimic closely the systems of electrochemical interest. 

The IV measurements on molecules and monolayers have been carried out almost exclusively using direct current (DC) frequency-dependent alternating current (AC) impedance measurements have rarely been performed, even though a rich spectroscopy may reveal itself, if the IV measurements were followed as a function of frequency v. 

Electrochemical Measurements. Cyclic voltammetry and alternating current (ac) impedance spectroscopy were performed using an ac impedance system (EG G Princeton Applied Research model 378) that included a potentiostat-galvanostat (model 273), a two-phase lock-in analyzer (model 5208), and an IBM PS/2 computer. For ac impedance measurements, a 5-mV sine wave was superimposed on an applied voltage bias from the potentiostat. The reference electrodes were saturated calomel electrodes (SCE Fisher) for measurements in aqueous solution and silver electrodes... 

K. Eckhard, H. Shill, B. MizaikofF, W. Schuhmann, C. Kranz, Alternating current (AC) impedance imaging with combined atomic force scanning electrochemical microscopy (AFM-SECM), Electrochem. Commun. 9 (2007) 1311-1315. 

The electrochemical impedance spectroscopy (EIS) method is very useful in characterizing an electrode corrosion behavior. The electrode characterization includes the determination of the polarization resistance (/J ), corrosion rate (Cfl), and electrochemical mechanism [1,4,6,19-28]. The usefulness of this method permits the analysis of the alternating current (AC) impedance data, which is based on modeling a corrosion process by an electrical circuit. Several review papers address the electrochemical impedance technique based on the AC circuit theory [22-24,29-30]. 

Alternating current (AC) impedance spectroscopy has been used to measure the conductivity of an amine-cured epoxy modified with multiwalled carbon nanotubes (MWNTs) (Sandler et al. 2003). The conductivity increased as a function of the MWNT weight fi-action, see O Fig. 55.5. There was an increase in conductivity of about two orders of magnitude, from 10 to 10 S/m, when 0.001 wt% of nanotubes was added. There was a further increase to... 

As well as CV and GCD analysis, another characterisation method that is often used to characterise supereapacitor materials is electrochemical impedance spectroscopy (EIS), or alternating current (AC) impedance spectroscopy. The following equation can be used to calculate the capacitance value from impedance measurements ... 

Proton condnctivity of PFSA membranes is most frequently measured from the alternating current (AC) impedance spectroscopic technique. The impedance (Z) is defined as the ratio of the voltage to the current at a given frequency, and it is represented as a complex quantity that consists of a real part (resistance, Z ) and an imaginary part (reactance, Z") with a phase angle 0 as described in the following equation ... 

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