Electrodeposition cathode process, efficiency

An important feature in electrodeposition is the efficiency of the cathodic process, i.e. the percentage of the cathodic current which is used to deposit the metal rather than produce hydrogen. A higher value is important in giving a better coating because hydrogen evolution causes porosity within the metal. 

This linear relation was revealed that both the ionic species and metallic species in the bulk electrolyte were associated with each other and the mass transfer of the metallic species contributed to the ionic conductivity. The mass transfer of the metallic species was also correlated with the ionic mobility. In the case of electrodeposition from this kind of [P2225KTFSA] including [Nd(TFSA>5] , the mobility of metallic ions and related complexes would be influenced by the current efficiency of the cathodic process. 

In an effort to mimic naturally occurring superhydrophobic and super sticky surfaces, electrochemical methods that incorporate the use of common chemical reactions are frequently used to fabricate superhydrophobic nanostructures. Cathodic electrodeposition offers an efficient way of fabricating nanostructures through a process that is low in cost, suitable for large scales, environmental friendly, easy to use, and suitable for low-temperature... 

The overvoltage or overpotential over is inserted in Eq. (3.20) to adjust for other processes that compete in the system and make electrodeposition less than ideally efficient. These processes are irreversible and include the effects of the decomposition of water, other solutes, and imperfections in the electrode surface. Because of these processes, a greater potential difference than calculated from the reference potential and the ionic concentration must be applied in order to achieve deposition. For the same reason, spontaneous deposition, inferred from a positive value of E°, may not occur if the overvoltage exceeds it. Overvoltage effects occur at both the cathode and the anode. 

Porous or particulate fixed bed electrodes have been recognized as the more efficient three-dimensional cathodes used for metal electrodeposition from dilute solutions, mainly due to their uniform effective conductivity of the solid phase. However, electrode clogging due to metal electrodeposition restricts their use as only for very dilute solutimis in which the long operational time would justUy their use [11, 12]. In order to overcome this Umitatimi and make the electrochemical process continuous, mobile electrodes, such as fluidized, spouted, and inclined bed electrodes, were proposed [13-16]. In these electrodes, the conductivity of the... 

When the electrolyte contains more than one cation, their simultaneous discharge becomes possible. This will occur if their deposition potentials (under the conditions used) are close to one another, and it can lead to alloy electrodeposition (q.v.). The most general case, however, is of course where hydrogen ion is the second cation, and the simultaneous evolution of hydrogen is a common accompaniment of metal deposition. The amount of current that will be dissipated in this way can be calculated if the current-potential curves for the two processes are known. It must be remembered that the curve for H2 evolution depends on the nature of the cathode surface as well as on the pH of the solution. Figure E.4 illustrates the deposition of zinc from a neutral solution of zinc sulphate. At the point at which the curves intersect the current efficiency for zinc deposition is 50%, but at high current densities it is much greater. 

---