Galvanic displacement method

Galvanic displacement method is also often used for synthesizing catalysts. By this method, low Pt-content electrocatalysts can be obtained. For example, a carbon-supported core—shell structured electrocatalyst with bimetallic IrNi as the core and platinum monolayer as the shell has been successfully synthesized using this method. In this synthesis, IrNi core supported on carbon was first synthesized by a chemical reduction and thermal annealing method and a Ni core and Ir shell structure could be formed finally. The other advantage of this method is that the Ni can be completely encased by Ir shell, which will protect Ni dissolve in acid medium. Secondly, IrNi PtML/C core—shell electrocatalyst was prepared by depositing a Pt monolayer on the IrNi substrate by galvanic displacement of a Cu monolayer formed by under potential deposition (UPD). 

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. 

Practical applications of the galvanic displacement reaction, when smooth or continuous coatings are required, are, obviously, quite limited. It seems that only very thin coatings limited to several tens of nm with a smooth surface morphology can be achieved by this method. This aspect should be very carefuUy kept in mind for the modem electronics or biomedical applications. Contrarily, when hydromet-allurgical applications are in question, i.e., solution purification, the galvanic displacement deposition is frequently a method of choice. This method is used... 

One approach to ALD of metals is a process known as surface-limited redox replacement or galvanic displacement. This method has been used to produce ultrathin layers of metals such as Pt, Pd, and Ag. - The ALD is brought about by the galvanic replacement of underpotentially deposited metal monolayers of less noble metals such as Pb or Cu. The surface-limited redox replacement occurs spontaneously, because the reduction potential of the less noble metal is more negative than that of the subsequent ALD layer. The two deposition steps in the surface-limited redox replacement of metals must be performed in separate solutions, so it is necessary to exchange reactants— much like the case of ALD by vapor deposition methods. 

Most of the previous SERS analysis required some pretreatment methods to extract melamine from real matrix. Betz and co-workers developed the fast SERS approach for detecting melamine in infant formula without the need for purification or additional equipment (Betz et al. 2012). Eor this purpose, a galvanic displacement of Cu by Ag was used to create Ag nanostructures on low-cost surfaces of Cu tape and coin and excellent SERS enhancement was obtained. A strong peak between 676 and 690 cm was observed and served to identify melamine contamination of the formula. Both the tape and coin enabled the detection of contamination down to the 5 ppb level which is up to 200x better than that using commercial Klarite substrates. 

Cementation is a method for recovering valuable or toxic metals from solution, in which a second metal, C, e.g. Zn and Fe, in solid powder form, displaces the dissolved metal ion, M", from aqueous solution by virtue of the galvanic cell reactions ... 

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