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Cyclic voltammetry (CV) is a type of potentiodynamic electrochemical measurement. In a cyclic voltammetry experiment, the working electrode potential is ramped linearly versus time. Unlike in linear sweep voltammetry, after the set potential is reached in a CV experiment, the working electrode's potential is ramped in the opposite direction to return to the initial potential. These cycles of ramps in potential may be repeated as many times as needed. The current at the working electrode is plotted versus the applied voltage to give the cyclic voltammogram trace. Cyclic voltammetry is generally used to study the electrochemical properties of an analyte in solution or of a molecule that is adsorbed onto the electrode.
Chronoamperometry is an electrochemical technique in which the potential of the working electrode is stepped and the resulting current from faradaic processes occurring at the electrode is monitored as a function of time. The functional relationship between current response and time is measured after applying single or double potential step to the working electrode of the electrochemical system. Limited information about the identity of the electrolyzed species can be obtained from the ratio of the peak oxidation current versus the peak reduction current. However, as with all pulsed techniques, chronoamperometry generates high charging currents, which decay exponentially with time as any RC circuit. The Faradaic current - which is due to electron transfer events and is most often the current component of interest - decays as described in the Cottrell equation. In most electrochemical cells this decay is much slower than the charging decay-cells with no supporting electrolyte are notable exceptions. Most commonly a three electrode system is used. Since the current is integrated over relatively longer time intervals, chronoamperometry gives a better signal to noise ratio in comparison to other amperometric techniques.
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In electrochemistry, overpotential is the potential difference (voltage) between a half-reaction's thermodynamically determined reduction potential and the potential at which the redox event is experimentally observed. The term is directly related to a cell's voltage efficiency. In an electrolytic cell the existence of overpotential implies that the cell requires more energy than thermodynamically expected to drive a reaction. In a galvanic cell the existence of overpotential means less energy is recovered than thermodynamics predicts. In each case the extra/missing energy is lost as heat. The quantity of overpotential is specific to each cell design and varies across cells and operational conditions, even for the same reaction. Overpotential is experimentally determined by measuring the potential at which a given current density is achieved.
Electroanalytical methods are a class of techniques in analytical chemistry which study an analyte by measuring the potential (volts) and/or current (amperes) in an electrochemical cell containing the analyte. These methods can be broken down into several categories depending on which aspects of the cell are controlled and which are measured. The three main categories are potentiometry, coulometry, and voltammetry.
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Electrochemical engineering is the branch of chemical engineering dealing with the technological applications of electrochemical phenomena, such as electrosynthesis of chemicals, electrowinning and refining of metals, flow batteries and fuel cells, surface modification by electrodeposition, electrochemical separations and corrosion. This discipline is an overlap between electrochemistry and chemical engineering.
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In electrochemistry, faradaic impedance is the resistance and capacitance acting jointly at the surface of an electrode of an electrochemical cell. The cell may be operating as either a galvanic cell generating an electric current or inversely as an electrolytic cell using an electric current to drive a chemical reaction. In the simplest nontrivial case faradaic impedance is modeled as a single resistor and single capacitor connected in parallel, as opposed say to in series or as a transmission line with multiple resistors and capacitors.
In electrochemistry, protein film voltammetry is a technique for examining the behavior of proteins immobilized on an electrode. The technique is applicable to proteins and enzymes that engage in electron transfer reactions and it is part of the methods available to study enzyme kinetics.
Electrochemical quartz crystal microbalance (EQCM) is the combination of electrochemistry and quartz crystal microbalance, which was generated in the eighties. Typically, an EQCM device contains an electrochemical cells part and a QCM part. Two electrodes on both sides of the quartz crystal serve two purposes. Firstly, an alternating electric field is generated between the two electrodes for making up the oscillator. Secondly, the electrode contacting electrolyte is used as a working electrode (WE), together with a counter electrode (CE) and a reference electrode (RE), in the potentiostatic circuit constituting the electrochemistry cell. Thus, the working electrode of electrochemistry cell is the sensor of QCM.
References
- 1 2 Vladimir Sergeevich Bagot'skiĭ, "Fundamentals Of Electrochemistry",John Wiley & Sons, 2006, p. 178. ISBN 9780471700586
- ↑ Bard, Allen; Faulkner, Larry (2001). Electrochemical Methods. Fundamentals and Applications (2nd ed.). Hoboken, NJ: John Wiley & Sons, Inc. ISBN 978-0-471-04372-0.
- ↑ Newman, John; Thomas-Alyea, Karen E. (2004). Electrochemical Systems (3rd ed.). Hoboken, NJ: John Wiley & Sons, Inc. ISBN 0-471-47756-7.
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