Tuning the Morphology of Gold Nanocrystals by Switching the Growth of {110} Facets from Restriction to Preference

Abstract

Single crystalline Au nanorods (Au NRs), synthesized via seed-mediated growth, show unique surface structures. Apart from the oft-observed {100} and {111} facets, unexpectedly, unstable {110} facets dominate in such nanorods due to {110} restricted growth. Unique properties have been suggested for the nanorods. One novel property, we believe, is that the the high-energy {110} endows the nanorod with a high reactivity, thus making the growth to more stable morphologies possible. Herein, by switching the growth to the {110} preference, we successfully obtained thermodynamically more stable morphologies (arrow-headed gold nanorods and gold nano-octahedra) with a high quality and yield. A blockade of selective underpotential deposition of silver is suggested to be responsible for the switching.

Synthesis and Characterization of Noble‐Metal Nanostructures Containing Gold Nanorods in the Center

“…[ [16][17][18][19] Specifically, Au nanorods have been transformed into various shapes via overgrowth on the entire surface [16][17][18] or the side surface of Au nanorods. [19] However, this strategy has not been widely extended to noble metals other than Au.…”

“…Only recent studies by Xiang et al and Becker et al showed a system, where Ag could grow on specific sides of Au nanorods to generate nanocrystals with a semicircular or triangular morphology. [17,20] Overall, it remains a challenge to find a simple way to control the overgrowth of other metals on Au nanorods in an effort to generate bimetallic nanocrystals with a core-shell structure and the desired properties.…”

Investigation of pH Effect on Gold Nanorod Synthesis

“…The surface energy of {110} facet is higher than {100} and {111} facet, resulting in that CTAB bilayer primarily absorbed onto the {110} facet. 17,31,32 Because greater surface energy means less stability, 33 gold atoms would preferentially deposit onto the {100} and {111} facet to form rod-shaped nanoparticles. When AgNO 3 is added into the growth solution, silver ions react with bromide ions to form AgBr, which would selectively absorb onto the {110} facet of the gold nanoseeds, further inducing the gold atoms to deposit onto the {100} facet.…”

Kinetics of Gold Nanorods Formation in Solution and Application on Aspect Ratio Tuning

“…Table 1. Summary of the gold nanorod size parameters in Fig.2 (final nanorods) and Fig.4 It is known that the single crystal gold nanorod has octagonal column morphology, with alternated {100} and {110} lateral facets [19], but Enrique and coworkers observed a higher-index lateral facets{250}, and predicted a plausible transition from the {250} to {110} [20]. This is very probably relevant to the two-stage growth model above, in which nanorods before and after the TP have different type of lateral facets, {250} and {110}, respectively.…”