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Electrochemical cathodic

Copper acetate was used in Ref. 38 it was noted that if chloride was used instead of acetate, no deposition occurred, and this was attributed to adsorption of chloride on the substrate (Pt). The berzelianite phase with a small amount of umangite impurity was obtained. The composition and phase of the film could be altered by electrochemical cathodic polarization (in an aqueous K2SO4 solution). Initially, there occurred an increase in lattice parameters and decrease in x (Cu2-A Se). With continued polarization, a phase change occurred until eventually only orthorhombic Cui xSe was present in the film. The umangite phase also disappeared, and it was believed that this impurity phase catalyzed the phase transformation. The change in composition during cathodic polarization was attributed to reduction of zerovalent Se to Se, which was dissolved in the solution. Based on the study of Fohner and JeUinek [41] discussed earlier, this explanation can be interpreted as reduction of Sei ( monovalent Se) to Se (divalent Se). [Pg.242]

Figure 13. Electrochemical cathodic aging experiments under current-controlled conditions (cc) on a lightly doped SrTi03 wafer. All experiments were performed in 1M NaOH. ((1) virgin SrTiOs (2) cathodically aged 0.2 mA-cc for 25 h ... Figure 13. Electrochemical cathodic aging experiments under current-controlled conditions (cc) on a lightly doped SrTi03 wafer. All experiments were performed in 1M NaOH. ((1) virgin SrTiOs (2) cathodically aged 0.2 mA-cc for 25 h ...
Blaedel and Engstrom [48] noted that for a quasi-reversible process the current could be simply expressed in terms of the rate constant and mass-transport coefficient. Application of a square wave step in the rotation rate of a RDE (i.e., PRV, see Section 10.4.1.3) resulted in modulation of the diffusion-limited current and hence modulation of the mass-transfer coefficient. By solving the appropriate quadratic equation it was possible to derive a value for the heterogeneous rate constant for the electrochemical cathodic, kf, or anodic, kb, process of interest. Values for the standard heterogeneous rate constant and transfer coefficient were subsequently... [Pg.422]

The electrochemical cathode processing can form Pt particles on the sample surfaces and inside pore channels. The SEM images (Fig. 1) demonstrate a presence of Pt particles both at the sample surface and in the inlets of pore channels. Therefore, this evidence is supposed to explain a good adhesion of... [Pg.594]

Electrochemical cathodic reductions of acetylcyclopropanes in ammonia solution, with butyl-trimethylammonium tetrafluoroborate as supporting electrolyte, gave the same products as in the lithium/ammonia reductions. However, when tetraethylammonium tetrafluoroborate was employed, tertiary alcohols, e.g. 33 were isolated. The ethyl groups were probably incorporated by anionic attack on the initially formed ketones. [Pg.2498]

Figure 8-1. Left Electronic energies of electrode and redox molecule at different solvent polarization P. Pro and Ppo are the equilibrium values of P in the initial and final stafes, respectively. Right Potential free energy surfaces for electrochemical (cathodic) electron transfer. From ref 25 with permission. Figure 8-1. Left Electronic energies of electrode and redox molecule at different solvent polarization P. Pro and Ppo are the equilibrium values of P in the initial and final stafes, respectively. Right Potential free energy surfaces for electrochemical (cathodic) electron transfer. From ref 25 with permission.
Obtaining solvated electrons by dissolving alkali metals and by electrochemical generation is of special interest. Back in the last century, the dissolution of alkali metals in liquid ammonia gave the very first evidence of obtaining solvated electrons. Electrochemical (cathodic) generation of solvated electrons is a process in which electrons are transferred from the electrode into solution under the action of high cathode potentials. [Pg.168]

Most metals occur naturally in their oxide or sulfide forms. The process of metal refining converts these ores into pure metals. Thermodynamically, a metal will return spontaneously to its original oxide form. Metal oxidation can occur at high temperatures, by direct reaction with O2, or at a moderate temperature by reaction with water, O2, and/or H+. The latter oxidation, commonly referred to as wet corrosion, has as its basis the combination of electrochemical cathodic reduction and anodic metal oxidation reactions into a corrosion cell. Thus, many corrosion processes are... [Pg.1805]

FIGURE 22 Scheme of the Ca-P (HA) layer growth mechanism on the porous surface during electrochemical cathodic deposition a—>c - stages of the HA growth... [Pg.373]

W, Chen, Q., and Ji, X. (2013) Electrochemically cathodic exfo-Uation of graphene sheets in room temperature ionic liquids N-butyl, methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and their electrochemical properties. Electrochim. Acta, 113, 9—16. [Pg.155]

Figure 2. Follow-up processes occurring after electrochemical cathodic production of a carbanion. Aromatics in nonaqueous aprotic solvents give R and R" species which are relatively stable R- > R . Figure 2. Follow-up processes occurring after electrochemical cathodic production of a carbanion. Aromatics in nonaqueous aprotic solvents give R and R" species which are relatively stable R- > R .
In this section, a summary of the chemical principles involved with membrane reactors for desulfurization are overviewed. The details will be covered in the following sections. Electrochemical desulfurization technologies assisted by membranes have been extensively explored for the removal of sulfur that exists in sulfur compounds in fossil fuels and in SO2 form in flue gas. In principle, SO2 can be absorbed by an aqueous electrolyte solution and then electrochemically converted into species such as sulfate, hydrogen sulfide, and sulfur, among others, by oxidation or reduction processes, whereas the sulfur compounds in fossil fuels can be similarly removed. The universal reaction mechanism of the electrochemical cathodic reduction of organic sulfur compounds in gasoline and diesel is shown in Eqn (14.1) (Lam et al., 2012) ... [Pg.399]

Work related to the use of nonplatinum catalysts for electrochemical (cathodic) oxygen reduction is discussed in Section 12.6. [Pg.221]

This occurred during 4,000 h of operation at 120°C, and resulted in the decrease of the cathode catalyst layer thickness. This may be due to the oxidation of the carbon snpport by the H O, which was formed during the oxygen reduction reaction. Snbstantial crystallite growth of platinnm catalyst was observed in that region. X-ray diffraction measurement indicated that the crystallite size of the platinum catalyst increased from 2 to 8nm. The electrochemical cathode... [Pg.258]

In Figure 9.5, the electrochemical cathodic protection of Fe (Ep z+ p = -0.447 V) with Zn (E 2+ = -0.762 V) is shown. Until Zn is completely dissolved, Fe will not be corroded because Fe is the cathode and the electrochemical corrosion is an anodic reaction, which takes place at the Zn surface. [Pg.181]


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See also in sourсe #XX -- [ Pg.14 , Pg.17 , Pg.289 ]




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