Galvanic replacement reaction

Galvanic replacement reactions with small silver nanoparticies have been studied in detail by Lu et al. [132], They found that a complete gold shell did not form on the surface of each individual silver nanoparticle template. Instead, the replacement reaction resulted in the formation of alloy nanorings and nanocages from multiply-twinned silver nanoparticies of decahedral or icosahedral shape. 

Figure 11.57 SEM images of four different stages of galvanic replacement reaction with Ag nanocubes serving as the sacrificial template. (A to D) Ag nanocubes with sharp comers titrated with 0.1 mM HAUCI4,0,0.6,1.6, and 3.0 mL, respectively. (E to H) Ag nanocubes with truncated comers reacted with the same volumes of 0.1 mM HAuCld as for the sharp cubes. (Inset) TEM image of each respective sample. Reprinted with permission from reference [134]. (2006) American Chemical Society.

Bansal, V., Jani, H., Plessis, D. J., Coloe, P. J., and Bhargava, S. K. (2008). Galvanic Replacement Reaction on Metal Films A One-Step Approach to Create Nanoporous Surfaces for Catalysis. Advanced Materials 20 lYl-TlB. 

Hollow Pd nanospheres (HPNs) [29] Galvanic replacement reaction PDDA- MWCNTs 0.50 V (vs. Ag/AgCl) Better Es and current density than Pd nanoparticles. Current density is 2.5 x higher... 

However, UPD method cannot be used to prepare Pt monolayer on other metals readily because of the mismatched redox potentials. Adzic and coworkers developed a method to deposit Pt monolayer on metal substrates indirectly [59c]. In this approach, a sacrificial copper monolayer is first deposited on a selected metal using the UPD method, followed by a galvanic replacement reaction by Pt ions (Fig. 2.13) [60]. This approach successfully broadens the possible metal elements that can be directly or indirectly deposited by this technique. 

FIGURE 2.13 Schematic illustration of the synthesis of Pt monolayer on metal nanoparticles using UPD followed by a galvanic replacement reaction. Reprinted with permission from Ref. [21]. Elsevier B.V. 

Chen JY, WUey B, McLellan J, Xiong YJ, Li ZY, Xia YN (2005) Optical properties of Pd-Ag and Pt-Ag nanoboxes synthesized via galvanic replacement reactions. Nano Lett 5 2058-2062... 

Fig. 6.2 Schemes of two methods to fabricate Pt (or Pd) skin on BMNCs. (a) Pt monolayer forms on the alloy of Pt and an early transition metal through the dealloying process during annealing, (b) A Cu monolayer forms through UPD, followed by the galvanic replacement reaction between the Cu and PtCL( or PdCU ions...

Fig. 6.9 Scheme of the galvanic replacement reaction between Pd nanocubes and PtCl ions in the presence of Br as the capping agent. Reprinted with permission from ref. [50]... 

Combination of Underpotential Deposition and the Galvanic Replacement Reaction... 

Zhang H, Jin M, Wang J, li W, Camargo PHC, Kim MJ, Yang D, Xie Z, Xia Y (2011) Synthesis of Pd-Pt bimetallic nanocrystals with a concave structure through a bromide-induced galvanic replacement reaction. J Am Chem Soc 133 6078... 

Seo, D., and Song, H. (2009) Asymmetric hollow nanorod formation through a partial galvanic replacement reaction, / Am. Chem. Soc., 131(51), 18210-18211. 

Tan et al. prepared Ag Pt core-shell nanocubes by the coreduction of Ag and PtCl vvith sodium citrate [179]. The Ag cores could be removed by adding bis-(p-sulfonatophenyl) phenylphosphine (BSPP) solution to form hollow Pt nanocubes (Figure 10.14a). Similarly, Li et al. used Co nanoparticles as sacrificial templates to produce Pt hollow spheres [95], the shells of which was made primarily of Pt nanocrystaUites. Galvanic replacement was also employed to create hollow spheres by Liang et al. (Figure 10.14b) [94]. Finally, Selvakannan and Sashy used the galvanic replacement reaction between silver nanoparticles and chloroplatinate ions in chloroform to create platinum hollow nanoparticles [180]. 

Alloying and dealloying processes involved in the preparation of metal nanoshells through a galvanic replacement reaction, Y. Sun and Y. Xia, Nano Lett, 2003, 3, 1569. 

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