Coalescence of Ag2S and Au nanocrystals at room temperature

Metal-Based Composite Nanomaterials

“…Instead of the formation of ternary PbS-Au-Ag nanocomposites with multiple Au domains and Ag 2 S shell distributed at intervals on the surface of PbS nanocrystals, PbS@Ag 2 S-Au heterodimers are also the dominant products in this deposition sequence, as characterized in Fig. 3.32e-h. A possible mechanism accounting for the formation of PbS@Ag 2 S-Au heterodimers under this experimental condition could be proposed upon the coalescence of Au and Ag 2 S nanocrystals at room temperature (Qu et al 2011). As schematically illustrated in Fig.…”

“…3.33, the deposition of Ag on the PbS-Au nanocomposites firstly results in a continuous Ag 2 S shell covered on the surface of PbS core, which led to the detachment of Au domains from the surface of PbS nanocrystals. Then, the detached Au dots coalesce with core-shell PbS@Ag 2 S nanocrystals via a dissolution and renucleation process, which is driven by the equilibration of the Fermi levels in the two different types of particles (Ag 2 S shell and Au dots) (Qu et al 2011). Briefly, Au dots and core-shell PbS@Ag 2 S nanocrystals undergo Brownian encounters in their physical mixture, and then, electrons may tunnel from Au atoms on the surface of Au dot to its neighboring Ag 2 S shell due to the energy-level alignment.…”

“…Besides the more conventional hybrid nanomaterials, e.g., core-shell (Habas et al 2007;Joo et al 2009;Zhou et al 2009), alloy (Sun et al 2000;Shevchenko et al 2002;Liu et al 2009), and bimetallic heterostructures Guo et al 2008;Chen et al 2009b;Lim et al 2009), there has been increasing interest devoted toward the development of semiconductor-metal nanocomposites that consist of different classes of materials with solid-state interfaces Yang et al , b, 2009Zhao et al 2010;Li et al 2011;Qu et al 2011;Ding et al 2012;Haldar et al 2012;. This type of nanostructures combines materials with distinctly different physical and chemical properties to yield a unique hybrid nanosystem with multifunctional capabilities and tunable or enhanced properties that may not be attainable otherwise.…”

“…There is also an increased interest in the synthesis of more complex nanostructures because of the promise of tunable properties for a new generation of technology-driven applications in catalysis (Liz-Marzán et al 1996;Toshima and Yonezawa 1998;Davies et al 1998;Kim et al 2002b), chemical and biological sensing (Taton et al 2000;Krasteva et al 2002), and optics (Murphy and Jana 2002; Kim et al 2002a). As presented in this book, after the remarkable success in synthesizing more conventional hybrid nanomaterials, for example, core-shell (Habas et al 2007;Joo et al 2009;Zhou et al 2009), alloy (Sun et al 2000;Shevchenko et al 2002;Liu et al 2009), and bimetallic heterostructures with controlled dimensions and intriguing morphologies Guo et al 2008;Lim et al 2009;Kim et al 2010;, there has been increasing interest devoted toward the development of nanocomposites that consist of different classes of materials with solid-state interfaces , 2011Zhao et al 2010;Li et al 2011;Qu et al 2011;Haldar et al 2012;Ding et al 2012;. The lure of these nanostructured composites is that they combine materials with distinctly different physical and chemical properties to yield a unique hybrid system with tunable optical properties Chapter 1 Introduction (Jin and Gao 2009;Zhang et al 2010), enhanced photocatalytic activities (Jakob et al 2003;Subramanian et al 2004;Salant et al 2006;, and ultrafast carrier dynamics (Ma et al 2004;Lin et al 2006).…”

Cage-bell structured Au–Pt nanomaterials with enhanced electrocatalytic activity toward oxygen reduction

“…Citrate-stabilized Au (w7 nm) and Ag (w10 nm) nanoparticles (seed particles) were prepared by the NaBH 4 reduction of HAuCl 4 [24] and AgNO 3 [25], respectively. An aqueous solution of HAuCl 4 or AgNO 3 (1 mM, 50 mL) was mixed with 2 mL of 100 mM aqueous sodium citrate solution used as stabilizer.…”