Electrodeposition electrodeposited charge

P. V. Kamat S. Barazzouk S. Hotchandani K. George Thomas, Nanostructured Thin Films of C o-Anline Dyad Clusters. Electrodeposition, Charge Separation and Photoelectrochemistry. Chem., Euro. J. 2000, 6, 3914-3921. 

Figure 4 Thickness of Cu thin films as function of deposition time, as calculated from RBS measurements and from electrodeposited charge. Films were electrode-posited at -0.5V, from a 0.104M CuS04 + 0.5 M Na2S04 bath. 

The electrodeposition of Ag has also been intensively investigated [41 3]. In the chloroaluminates - as in the case of Cu - it is only deposited from acidic solutions. The deposition occurs in one step from Ag(I). On glassy carbon and tungsten, three-dimensional nucleation was reported [41]. Quite recently it was reported that Ag can also be deposited in a one-electron step from tetrafluoroborate ionic liquids [43]. However, the charge-transfer reaction seems to play an important role in this medium and the deposition is not as reversible as in the chloroaluminate systems. 

It is apparent (Fig. 1.21) that at potentials removed from the equilibrium potential see equation 1.30) the rate of charge transfer of (a) silver cations from the metal to the solution (anodic reaction), (b) silver aquo cations from the solution to the metal (cathodic reaction) and (c) electrons through the metallic circuit from anode to cathode, are equal, so that any one may be used to evaluate the rates of the others. The rate is most conveniently determined from the rate of transfer of electrons in the metallic circuit (the current 1) by means of an ammeter, and if / is maintained constant it can eilso be used to eveduate the extent. A more precise method of determining the quantity of charge transferred is the coulometer, in which the extent of a single well-defined reaction is determined accurately, e.g. by the quantity of metal electrodeposited, by the volume of gas evolved, etc. The reaction Ag (aq.) -t- e = Ag is utilised in the silver coulometer, and provides one of the most accurate methods of determining the extent of charge transfer. 

After rinsing and dry-off, the primer is applied. In most modern plants this means electrodeposition of the primer (Section 14.1). The most widely used primers are cathodic. The body shell is made the cathode and current flows between it and inert anodes in the electropaint bath. The paint is formulated so that the resin is basic and, when neutralised with an acid such as lactic acid, becomes positively charged. The most widely used resins are epoxy-amine adducts ... 

The other method is cadmium electrodeposition on a nickel-plated steel foil (serving as current collector) using a plating bath containing acidified cadmium sulfate (type AB2C3). In this case the user is supplied with a battery in charged ( ready for use ) condition. 

Zinc is electrodeposited from the sodium zincate electrolyte during charge. As in the zinc/bromine battery, two separate electrolytes loops ("posilyte" and "nega-lyte") are required. The only difference is the quality of the separator The zinc/ bromine system works with a microporous foil made from sintered polymer powder, but the zinc/ferricyanide battery needs a cation exchange membrane in order to obtain acceptable coulombic efficiencies. The occasional transfer of solid sodium ferrocya-nide from the negative to the positive tank, to correct for the slow transport of complex cyanide through the membrane, is proposed [54],... 

Electrodeposition of metals can be performed under different electrochemical modes. In the work mentioned in Ref. [18], it was performed in potentiostatic mode. The potential value for formation of platinum nanoparticles is —25 mV vs. SCE the deposition is performed from 2.5 mM solution of H2[PtCl6] in 50 mM KCl. The size of nanoparticles formed depends on the reduction charge. Continuous monitoring of the charge in potentiostatic mode is provided by different potentiostats, for example, by Autolab-PG-stat (EcoChemie, The Netherlands). Conditions for deposition of other metals should be selected according to their electrochemical properties. 

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