Surface Segregated AgAu Tadpole‐Shaped Nanoparticles Synthesized Via a Single Step Combined Galvanic and Citrate Reduction Reaction

Abstract

New AgAu tadpole nanocrystals were synthesized in a one-step reaction involving simultaneous galvanic replacement between Ag nanospheres and AuCl4(-)(aq.) and AuCl4(-)(aq.) reduction to Au in the presence of citrate. The AgAu tadpoles display nodular polycrystalline hollow heads, while their undulating tails are single crystals. The unusual morphology suggests an oriented attachment growth mechanism. Remarkably, a 1 nm thick Ag layer was found to segregate so as to cover the entire surface of the tadpoles. By varying the nature of the seeds (Au NPs), double-headed Au tadpoles could also be obtained. The effect of a number of reaction parameters on product morphology were explored, leading to new insights into the growth mechanisms and surface segregation behavior involved in the synthesis of bimetallic and anisotropic nanomaterials.

Bimetallic Au@Pd‐Au Tadpole‐Shaped Asymmetric Nanostructures by a Combination of Precursor Reduction and Ostwald Ripening

“…They can be described as having a spherical head and a high aspect ratio tail, being potential candidates for application as nanomotors and as building blocks to more complex structures since their properties may depend on particle orientation . Despite these very attractive features, the design and synthesis of bimetallic asymmetric heterostructures, including tadpoles, remain very challenging and limited to only a few systems and compositions . Hence, a better understanding of the various factors and growth mechanisms that lead to the formation of asymmetric heterostructures is essential to enable their rational synthesis and realize their use in potential applications.…”

“…Bimetallic and asymmetric heterostructures represent an emerging class of nanomaterial . These particles enable the combination of distinct compositions, shapes, and physicochemical features within a single particle, thus leading to intriguing and novel properties .…”

“…These particles enable the combination of distinct compositions, shapes, and physicochemical features within a single particle, thus leading to intriguing and novel properties . Bimetallic tadpoles represent an important category of asymmetric nanostructure . They can be described as having a spherical head and a high aspect ratio tail, being potential candidates for application as nanomotors and as building blocks to more complex structures since their properties may depend on particle orientation .…”

Synthesis of Colloidal Metal Nanocrystals: A Comprehensive Review on the Reductants

“…The general protocol for chemically synthesizing metal nanocrystals involves the reduction of a salt precursor by a reductant in the solution phase. By judicially choosing the right capping agents, metal nanocrystals with a variety of well‐defined shapes or structures have been synthesized . However, the explicit role(s) of reductants is still ambiguous and deserves special attention.…”

Quantitatively in Situ Imaging Silver Nanowire Hollowing Kinetics

“…in 2004, the nanoscale Kirkendall effect has been exploited for fabrication of hollow nanoparticles and nanotubes, − during which coalescence of Kirkendall voids gives rise to a single hollow cavity in each nanoparticle. Compared to other methods such as self-rolling, oriented attachment, and pore wetting, the nanoscale Kirkendall-based synthesis distinguishes itself in many aspects: it is template free, works well with both binary and ternary material systems, and allows the rational design of the structure. ,, The morphological evolution of nanoparticles and the mass diffusion kinetics involved in the nanoscale Kirkendall process are complex. Experimentally, transmission electron microscopy (TEM) has been used to study the Kirkendall effect − in nanoparticles or nanowires by ex situ characterizing the intermediate products formed at different reaction stages.…”