Galvanic displacement

Ft partial and full monolayers have been deposited onto alternative metal particle cores. Brankovic, Wang, and Adzic found Ft spontaneously deposited onto hydrogen-reduced Ru particles at a surface coverage of 0.11 and 0.50. An alternative method of depositing Ft onto Fd, Fd alloy, and Au particles has been developed by Sasaki et al. and Zhang et al. This involves the deposition of a Cu overlayer by underpotential deposition followed by galvanic displacement by Ft. Complete monolayers of Ft have been claimed and the technique has been extended to preparation of mixed monolayers of Ft and other precious metals. ... 

Since the first report of dendrimer-encapsulated Cu nanoparticles [15], several types of mono and bi-metallic DENs have been prepared. DEN synthesis has been recently reviewed [9,16], so only the synthesis of bimetallic DENs is described here. Bimetallic DENs can be prepared by one of three methods co-complexation of metal salts, galvanic displacement, and sequential reduction. Several bimetallic systems have already been prepared inside PAMAM dendrimers Table 1 summarizes the current literature and synthetic methods employed. 

Electroless plating should not be confused neither with the electrochemical (galvanic) displacement deposition - process involving the oxidation (dissolution) of the metallic substrate and concomitant reduction of metallic ions in solution - nor with the homogeneous chemical reduction process - indiscriminate deposition over all objects in contact with the solution. 

E-Beam Lithography And Spontaneous Galvanic Displacement Reactions For Spatially Controlled... 

An alternative and very promising approach to realize substrates suitable for MEF applications is based on spontaneous galvanic displacement reactions (SGDR). Similarly to other deposition techniques previously described, SGDR permits the fabrication of extended metallic substrates additionally, it allows to control and optimize the surface roughness of the metal film in order to obtain efficient MEF processes, while maintaining an appreciable uniformity of the morphology over the entire sample. 

Carraro, C., Maboudian, R., and Magagnin, L. (2007). Metallization and nanostructuring of semiconductor surfaces by galvanic displacement processes. Surf. Sci. Rep. 62 499-525. 

Vasilica, R., and Dimitrov, N. (2005). Epitaxial Growth by Monolayer-Restricted Galvanic Displacement. Electrochem. Solid-State Lett, 8 C173-C176. 

O autocatalytic deposition, A codeposition with Ni or Co, galvanic displacement. 

When nickel metal is placed in a borohydride or a DMAB bath, initial deposition of gold proceeds by galvanic displacement, as a result of which a small amount of nickel dissolves into the bath. 

When electroless gold must be deposited on nickel metal, the common practice is to precoat the nickel with galvanic displacement gold prior to plating electroless... 

It is obvious that the galvanic displacement deposition occurs only at the surface of less noble metal (powders or various shape substrates). 

From a theoretical point of view, if a monolayer of the noble metal is deposited onto the surface of less noble metal, then thicker deposits under the conditions of galvanic displacement cannot be deposited. However, as experimentally observed, this is not true. Deposits thicker than one monolayer have frequently been observed using the galvanic displacement deposition. 

Figure 1. Galvanic displacement deposition of a more noble metal (M2) on a less noble metal (Mi) on a flat (a) and powder (b) substrates.

Although the galvanic displacement can quite successfully be used for the production of catalytic surfaces, electrolyte and water purification as well as for heavy or noble metal removal in hydromet-allurgical plants, it seems that the use of this type of deposition is limited in the sophisticated electronics or biomedical applications due to poor adherence and porosity of the deposited film. It is obvious that further studies are required if this process is aimed for the use in electronics, biomedical, or hi-tech industries. 

For the electronics and biomedical applications, the galvanic displacement deposition can be successful when very thin films are required and when an appropriate surface pretreatment is carried out to achieve a good adhesion of the deposited metallic film. 

The galvanic displacement deposition proceeds exclusively at the surface of a less noble metal, which acts as the reducing agent. 

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