Electro-assisted deposition

These reduction reactions are, of course, in competition with the direct reduction of cationic metal centers. As a result, reduction potential of the metallic precursors must be inferior to those of reactions (9.21), (9.23), and (9.24) not only to avoid reduction of the precursor but also to promote the local 

---

Both reactions generate OH ions that increase the interfacial pH in the vicinity of the cathode, which catalyzes the sol-gel process facilitating the film formation. The process is illustrated in Figure 12.2. van Ooij and coworkers [10] showed the enhancement in forming an interfacial layer of —Si—O—metal covalent bond by electrodeposition of silane on aluminum alloys. There are three major advantages of the electrodeposition approach, as clearly pointed out by Mandler and coworkers in their first publication [2] (1) the pH varies only close to the cathode, so the stability of the bulk solution is not affected (2) the deposition process is controllable by electrochemical parameters and (3) the film deposition is restricted to the conducting part of the surface and is controlled by the kinetics of the electrochemical process. Note that some reports refer this approach as electro-assisted deposition, since it is an indirect electrodeposition process where the sol monomer is not directly involved in the electrochemical reactions [15,19,28,29]. 

Also of interest are models from closely related fields, such as Matrix Assisted Laser Desorption/Ionization (MALDI) and Electro Spray Ionization Mass Spectrometry (ESI-MS). MALDI in particular attracts attention as this technique records the large molecular ion emissions resulting from the localized deposition of energy occurring on laser irradiation of the solid s surface. Indeed, there appear to be many similarities in the recorded emissions from SIMS and MALDI. Examples of areas of interest include processes described within the Cluster-based mechanisms and the pooling mechanism. These along with their applicability to SIMS are discussed in Section 3.3.4.2. 

---