Colloidal Synthesis of Metal Nanocrystals: From Asymmetrical Growth to Symmetry Breaking

Abstract

Nanocrystals offer a unique platform for tailoring the physicochemical properties of solid materials to enhance their performances in various applications. While most work on controlling their shapes revolves around symmetrical growth, the introduction of asymmetrical growth and thus symmetry breaking has also emerged as a powerful route to enrich metal nanocrystals with new shapes and complex morphologies as well as unprecedented properties and functionalities. The success of this route critically relies on our ability to lift the confinement on symmetry by the underlying unit cell of the crystal structure and/or the initial seed in a systematic manner. This Review aims to provide an account of recent progress in understanding and controlling asymmetrical growth and symmetry breaking in a colloidal synthesis of noble-metal nanocrystals. With a touch on both the nucleation and growth steps, we discuss a number of methods capable of generating seeds with diverse symmetry while achieving asymmetrical growth for mono-, bi-, and multimetallic systems. We then showcase a variety of symmetry-broken nanocrystals that have been reported, together with insights into their growth mechanisms. We also highlight their properties and applications and conclude with perspectives on future directions in developing this class of nanomaterials. It is hoped that the concepts and existing challenges outlined in this Review will drive further research into understanding and controlling the symmetry breaking process.

Large Au@Pd/PdOx core–porous shell nanoparticles as efficient ethanol oxidation electrocatalysts

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Noble Metal Nanoparticle-Loaded Porphyrin Hexagonal Submicrowires Composites (M-HW): Photocatalytic Synthesis and Enhanced Photocatalytic Activity

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Controlled synthesis of monodisperse gold nanorods with a small diameter of around 10 nm and largest plasmon wavelength of 1200 nm

“…According to literature reports, this dimensional change of AuNR caused by an increase in the amount of silver ions is well in line with the structural evolution governed by the Ag-UPD effect. 50,53,54 According to the TEM images, AuNRs acquired from different amounts of silver ions all display good size uniformity, suggesting a good monodispersity of the particle. Based on the size measurement of AuNRs, it is shown that as the amount of silver ions was increased from 0.15 mL to 0.8 mL, the length of AuNRs increases from 41.8 AE 1.7 nm to 83.2 AE 3.3 nm, and the diameter decreases from 16.9 AE 0.7 nm to 10.5 AE 0.6 nm (see Table S1 and Fig.…”