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Cyclic Voltammetry
In electrochemistry, cyclic voltammetry (CV) is a type of voltammetric measurement where the potential of the working electrode 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 in potential are repeated until the voltammetric trace reaches a cyclic steady state. The current at the working electrode is plotted versus the voltage at the working electrode to yield the cyclic voltammogram (see Figure 1). 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. Experimental method In cyclic voltammetry (CV), the electrode potential is ramped linearly versus time in cyclical phases. The rate of voltage change over time during each of these phases is known as the scan rate (V/s). In a standar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
For Wikipedia 2 With White Background
For or FOR may refer to: English language *For, a preposition#Definition, preposition *For, a complementizer *For, a grammatical conjunction#Types of conjunction, grammatical conjunction Science and technology * Fornax, a constellation * for loop, a programming language statement * Frame of reference, in physics * Field of regard, in optoelectronics * Forced outage rate, in reliability engineering Other uses * Fellowship of Reconciliation, a number of religious nonviolent organizations * Fortaleza Airport (IATA airport code), an airport in Brazil * Revolutionary Workers Ferment (''Fomento Obrero Revolucionario''), a small left communist international * Fast oil recovery, systems to remove an oil spill from a wrecked ship * Field of Research, a component of the Australian and New Zealand Standard Research Classification * FOR, free on rail, a historic form of international commercial term or Incoterms, Incoterm * "For", a song by Dreamcatcher from ''Apocalypse: Save Us'', 2022 Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diffusion Layer
In electrochemistry, the diffusion layer, according to IUPAC, is defined as the "region in the vicinity of an electrode where the concentrations are different from their value in the bulk solution. The definition of the thickness of the diffusion layer is arbitrary because the concentration approaches asymptotically the value in the bulk solution". The diffusion layer thus depends on the diffusion coefficient () of the analyte and, for voltammetric measurements, on the scan rate (V/s). It is usually considered to be some multiple of \sqrt (where \tfrac 1 t = scan rate). The value is physically relevant since the concentration of solute varies according to the expression derived from Fick's laws: \frac=\operatorname\left(\frac\right) where is the error function In mathematics, the error function (also called the Gauss error function), often denoted by , is a function \mathrm: \mathbb \to \mathbb defined as: \operatorname z = \frac\int_0^z e^\,\mathrm dt. The integral he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrolyte
An electrolyte is a substance that conducts electricity through the movement of ions, but not through the movement of electrons. This includes most soluble Salt (chemistry), salts, acids, and Base (chemistry), bases, dissolved in a polar solvent like water. Upon dissolving, the substance separates into cations and anions, which disperse uniformly throughout the solvent. Solid-state electrolytes also exist. In medicine and sometimes in chemistry, the term electrolyte refers to the substance that is dissolved. Electrically, such a solution is neutral. If an electric potential is applied to such a solution, the cations of the solution are drawn to the electrode that has an abundance of electrons, while the anions are drawn to the electrode that has a deficit of electrons. The movement of anions and cations in opposite directions within the solution amounts to a current. Some gases, such as hydrogen chloride (HCl), under conditions of high temperature or low pressure can also functi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Voltammetry
Voltammetry is a category of electroanalytical methods used in analytical chemistry and various industrial processes. In voltammetry, information about an analyte is obtained by measuring the current as the potential is varied. The analytical data for a voltammetric experiment comes in the form of a voltammogram, which plots the current produced by the analyte versus the potential of the working electrode. Theory Voltammetry is the study of current as a function of applied potential. Voltammetric methods involve electrochemical cells, and investigate the reactions occurring at electrode/electrolyte interfaces. The reactivity of analytes in these half-cells is used to determine their concentration. It is considered a dynamic electrochemical method as the applied potential is varied over time and the corresponding changes in current are measured. Most experiments control the potential (volts) of an electrode in contact with the analyte while measuring the resulting current (am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Counter Electrode
Counter may refer to: Mathematics and computing * Counter machine, a subclass of register machines * Counter (digital), an electronic circuit that counts rising or falling edges of a clock signal * Loop counter, the variable that controls the iterations of a loop * Jeton, a reckoning counter used on reckoning boards for calculations * Mechanical counter, a digital counter using mechanical components * Tally counter, a mechanical counting device * Web counter, a counter that counts the number of visits to a web page * Project COUNTER, a standard for reporting usage statistics of electronic resources * People counter, a device used to measure the number of people transversing a certain passage or entrance Games and sport * Counter (board wargames), a playing piece used in board wargames * Counter run, an offensive play in American football * Counter turn, an element in figure skating * Counter (collectible card games), a small item used to represent certain objects or conditions ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reference Electrode
A reference electrode is an electrode that has a stable and well-known electrode potential. The overall chemical reaction taking place in a cell is made up of two independent half-reactions, which describe chemical changes at the two electrodes. To focus on the reaction at the working electrode, the reference electrode is standardized with constant (buffered or saturated) concentrations of each participant of the redox reaction. There are many ways reference electrodes are used. The simplest is when the reference electrode is used as a half-cell to build an electrochemical cell. This allows the potential of the other half cell to be determined. An accurate and practical method to measure an electrode's potential in isolation ( absolute electrode potential) has yet to be developed. Aqueous reference electrodes Common reference electrodes and potential with respect to the standard hydrogen electrode (SHE): * Standard hydrogen electrode (SHE) (E = 0.000 V) activity of H+ = 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Film Voltammetry
In electrochemistry, protein film voltammetry (or protein film electrochemistry, or direct electrochemistry of proteins) is a technique for examining the behavior of proteins immobilized (either adsorbed or covalently attached) 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. Provided that it makes suitable contact with the electrode surface (electron transfer between the electrode and the protein is direct) and provided that it is not denatured, the protein can be fruitfully interrogated by monitoring current as a function of electrode potential and other experimental parameters. Various electrode materials can be used. Special electrode designs are required to address membrane-bound proteins. Experiments with redox proteins Small redox proteins such as cytochromes and ferredoxins can be investigated on condition that their electroactive coverage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction. There are two classes of redox reactions: * Electron transfer, Electron-transfer – Only one (usually) electron flows from the atom, ion, or molecule being oxidized to the atom, ion, or molecule that is reduced. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * Atom transfer – An atom transfers from one Substrate (chemistry), substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously, the oxidation state of oxygen decreases as it accepts electrons r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electrochemical Reaction Mechanism
In electrochemistry, an electrochemical reaction mechanism is the step-by-step sequence of elementary steps, involving at least one outer-sphere electron transfer, by which an overall electrochemical reaction occurs. Overview Elementary steps like proton coupled electron transfer and the movement of electrons between an electrode and substrate are special to electrochemical processes. Electrochemical mechanisms are important to all redox chemistry including corrosion, redox active photochemistry including photosynthesis, other biological systems often involving electron transport chains and other forms of homogeneous and heterogeneous electron transfer. Such reactions are most often studied with standard three electrode techniques such as cyclic voltammetry(CV), chronoamperometry, and bulk electrolysis as well as more complex experiments involving rotating disk electrodes and rotating ring-disk electrodes. In the case of photoinduced electron transfer the use of ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bordwell Thermodynamic Cycle
A Bordwell thermodynamic cycle use experimentally determined and reasonable estimates of Gibbs free energy (ΔG˚) values to determine unknown and experimentally inaccessible values. Overview Analogous to Hess's law which deal with the summation of enthalpy (ΔH) values, Bordwell thermodynamic cycles deal with the summation of Gibbs free energy (ΔG) values. Free energies used in these systems are most often determined from equilibriums and redox potentials, both of which correlate with free energy. This is with the caveat that redox scales are not absolute and thus it is important that all electrons are evaluated in redox pairs. This removes the offset of a given reference potential, otherwise the values are reported as potentials (V) against that reference. It is also worth recognizing that the values of the pKa system are just moderately transformed Keq values. When working with equilibrium energy values such as ΔG˚ and E˚1/2 values it common to employ a naught (˚) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cottrell Equation
In electrochemistry, the Cottrell equation describes the change in electric current with respect to time in a controlled potential experiment, such as chronoamperometry. Specifically it describes the current response when the potential is a step function in time. It was derived by Frederick Gardner Cottrell in 1903. For a simple redox event, such as the ferrocene/ferrocenium couple, the current measured depends on the rate at which the analyte diffuses to the electrode. That is, the current is said to be " diffusion controlled". The Cottrell equation describes the case for an electrode that is planar but can also be derived for spherical, cylindrical, and rectangular geometries by using the corresponding Laplace operator and boundary conditions in conjunction with Fick's second law of diffusion.Bard, A. J.; Faulkner, L. R. “Electrochemical Methods. Fundamentals and Applications” 2nd Ed. Wiley, New York. 2001. : i = \frac where, := current, in units of A : = number of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
