Electrochemical methods linear sweep voltammetry

The film electrodeposition process was studied by means of linear sweep voltammetry. The rate of electrochemical reaction was determined from current density (current-potential curves). The film deposits were characterized by chemical analysis, IR - spectroscopy, XRD, TG, TGA and SEM methods. 

Of hundreds of theoretically possible pathways, the list can be trimmed to four using linear sweep voltammetry (LSV) and chemical arguments [22]. The LSV method is an exceptionally powerful one for analyzing electrochemical processes [24-27]. From LSV studies, it was concluded that a single heterogeneous electron transfer precedes the rate-determining step, cyclization is first order in substrate, and that proton transfer occurs before or in the rate-determining step. The candidates include (a) e-c-P-d-p (radical anion closure). 

Other Phenomena Interaction of metallic Pb in the mercury phase [38] and amalgam decomposition in alkaline medium [39] have also been discussed. Formation of anodic monolayer PbCOs or Pb3(C03)2(0H)2 on Pb(Hg), depending on pH, in carbonate or bicarbonate solutions, has been detected using electrochemical methods (chronoamper-ometry and linear sweep voltammetry) and powder X-ray diffractometry [40]. 

A Gamry electrochemical measurements system and a Pine Bi-Potentiostat were used to study the experimental decomposition potential and current response to the applied voltage. The experimental variables were electrolyte flow rate and temperature. Linear sweep voltammetry (LSV) technique was the main method used to study the electrolytic processes. 

The electrochemical behavior of nimodipine was studied in ammonia buffer containing 10% (v/v) ethanol [8]. A single-sweep oscillopolaro-graphic method was then developed for nimodipine in tablets. The calibration graph (peak current at —0.73 V vs. concentration) was linear from 0.2 to 70 pM, and the detection limit was 10 pM. The same authors applied linear sweep voltammetry for the determination of nimodipine in tablets [9]. A reduction peak at —0.62V vs. the Ag/ACl reference... 

Cyclic voltammograms (CV) is a kind of electrochemical analysis method and is a linear-sweep voltammetry with the scan continued in the reverse direction at the end of the first scan this cycle can be repeated a number of times. Usually it is used in the field of electrochemistry. The function of CV in electrocatalytic analysis of electrodes might be in these parts (a) kinetics (b) mechanism of electrode reactions and (c) corrosion studies. 

Potential sweep methods which vary potential and measure current are widely used as they are easy techniques to employ. The methods include linear sweep voltammetry (LSV) and CV which can yield a large amount of electrochemical data in a short amount of time. These potential sweep methods are commonly used by inorganic chemists due to their ease of use and the information obtained. CV has appeared in the literature as the most popular electrochemical technique among inorganic chemists over the past three decades. Another advantage to potential sweep methods is that instrumentation is widely available at relatively low cost. Potential sweep methods usually involve varying the potential... 

In many preparative applications of EGBs the rate-determining step in product formation is the proton transfer. This is often the case when the deprotonated substrate is removed in a fast product-forming reaction (cf. Sec. II.B). For EGBs formed in situ, electrochemical methods such as cyclic voltammetry (CV), derivative cyclic voltammetry (DCV), linear sweep voltammetry (LSV), double-potential-step chronoamperometry (DPSC), and other electroanalytical methods can often be used to estimate the kinetics of proton transfer from the substrate to the EGB. When the EGBs are formed ex situ (because the acidic... 

Recently new methods, based on petturbations on the linear sweep voltammetry response of the mediator in the presence of the protein," a mediated thin-layer voltammetry technique, cyclic voltammetric simulation apphed to an electrochemically mediated enzyme reaction" have been setded to gain information on the protein-mediator interactions. More recendy the Scanning Electrochemical Microscopy (SECM) was used to probe the red-ox activity of individual cells of purple bacteria, by using two groups of mediators (hydrophilic and hydrophobic species) in order to gain information on the dependence of measured rate constant on the formal potential of the mediator in solution. By this technique an evaluation of the intracellular potential was also performed. ... 

Electrochemical methods of analysis are extremely sensitive and have been exploited to permit the detection of a wide range of analytical targets down to concentrations of the order 10 M in favorable conditions. The relative low cost of these electroanalytical techniques when compared with conventional techniques such as Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Atomic Absorption Spectroscopy (AAS) has led to the use of electrochemical stripping voltammetry (Chapter 2.3) and linear sweep voltammetry (Chapter 2.1) for the detection of both inorganic and organic species [1-6]. Target analytes that have been documented include heavy metals (Bi, Cu, Cd, Ga, Mn, Pb, Sb, Sn, V, Zn), cardiac and anticancer drugs, vitamins, and pesticides. However, the limits of applicability for these silent classical electrochemical techniques have been compromised by four main drawbacks ... 

Abstract Recent advances in molecular modeling provide significant insight into electrolyte electrochemical and transport properties. The first part of the chapter discusses applications of quantum chemistry methods to determine electrolyte oxidative stability and oxidation-induced decomposition reactions. A link between the oxidation stability of model electrolyte clusters and the kinetics of oxidation reactions is established and compared with the results of linear sweep voltammetry measurements. The second part of the chapter focuses on applying molecular dynamics (MD) simulations and density functional theory to predict the structural and transport properties of liquid electrolytes and solid elecfiolyte interphase (SEI) model compounds the free energy profiles for Uthium desolvation from electrolytes and the behavior of electrolytes at charged electrodes and the electrolyte-SEl interface. 

Thirdly, in order to improve the dispersion of platinum catalysts deposited on carbon materials, the effects of surface plasma treatment of carbon blacks (CBs) were investigated. The surface characteristics of the CBs were determined by fourier transformed-infrared (FT-IR), X-ray photoelectron spectroscopy (XPS), and Boehm s titration method. The electrochemical properties of the plasma-treated CBs-supported Pt (Pt/CBs) catalysts were analyzed by linear sweep voltammetry (LSV) experiments. From the results of FT-IR and acid-base values, N2-plasma treatment of the CBs at 300 W intensity led to a formation of a free radical on the CBs. The peak intensity increased with increase of the treatment time, due to the formation of new basic functional groups (such as C-N, C=N, -NHs, -NH, and =NH) by the free radical on the CBs. Accordingly, the basic values were enhanced by the basic functional groups. However, after a specific reaction time, Nz-plasma treatment could hardly influence on change of the surface functional groups of CBs, due to the disappearance of free radical. Consequently, it was found that optimal treatment time was 30 second for the best electro activity of Pt/CBs catalysts and the N2-plasma treated Pt/CBs possessed the better electrochemical properties than the pristine Pt/CBs. 

Table 3.1 presents a brief catalog of electrochemical techniques suitable for studying various aspects of metal CMP. Some instructive references are included for each application, but these are by no means exhaustive of the topics considered. Examples of experimental results for most of these techniques have been included later in this chapter. The linear sweep voltammetry (LSV) method listed in Table 3.1 is most frequently used in CMP research, and the phenomenological basis of this method is related to the mixed potential concept. The basic elements of cyctic voltammetry (CV), OCP, and electrochemical impedance spectroscopy (EIS) measurements are briefly noted below, and the other methods from the list of Table 3.1 are outlined later along with their apphcation-specific experimental data. 

This section describes the deposition and characterization of a Hg hemisphere on Pt UMEs (3). Two methods of fabricating hemispherical Hg/Pt UMEs are described electrodeposition from an inorganic mercnry solution or from controlled contact of the Pt UME with a mercury drop. Electrochemical characterization can be performed using linear sweep voltammetry, amperometry (see Chapter 11) and SECM feedback experiments (see Chapter 12). 

In potential sweep methods, the current is recorded while the electrode potential is changed linearly with time between two values chosen as for potential step methods. The initial potential, E, is normally the one where there is no electrochemical activity and the final potential, 2, is the one where the reaction is mass transport controlled. In linear sweep voltammetry, the scan stops at E2, whereas in cyclic voltammetry, the sweep direction is reversed when the potential reaches 2 and the potential remmed to j. This constitutes one cycle of the cyclic voltammogram. Multiple cycles may be recorded, for example, to study film formation. Other waveforms are used to study the formation and kinetics of intermediates when studying coupled chemical reactions (Figure 11.4c). 

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