Halide ions can trigger the oxidative etching of gold nanorods with the iodide ions being the most efficient

Over the years, scientists have identified various synthetic “handles” while developing wet chemical protocols for achieving a high level of shape and compositional complexity in colloidal nanomaterials. Halide ions have emerged as one such handle which serve as important surface active species that regulate nanocrystal (NC) growth and concomitant physicochemical properties. Halide ions affect the NC growth kinetics through several means, including selective binding on crystal facets, complexation with the precursors, and oxidative etching. On the other hand, their presence on the surfaces of semiconducting NCs stimulates interesting changes in the intrinsic electronic structure and interparticle communication in the NC solids eventually assembled from them. Then again, halide ions also induce optoelectronic tunability in NCs where they form part of the core, through sheer composition variation. In this review, we describe these roles of halide ions in the growth of nanostructures and the physical changes introduced by them and thereafter demonstrate the commonality of these effects across different classes of nanomaterials.

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“… 137 Oxidative etching of Au NRs by hydrogen peroxide and assisted by halide ions was also found to follow a similar trend. 138 …”

Section: Metal Nanocrystalsmentioning

confidence: 99%

The Many “Facets” of Halide Ions in the Chemistry of Colloidal Inorganic Nanocrystals

2018

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“…It has been reported that halide ions increase the oxidative etching of AuNRs efficiently because they promote the solubility of gold monoxide [98,99], particularly in iodine-mediated etching [100]. Iodine, acting as an oxidant, asymmetrically etches AuNRs in the presence of cetyltrimethylammonium (CTA + ) ions due to the low surface passivation at the end terminals, which leads to an AuNR shape conversion and color change [101,102,103,104].…”

Section: Etching-based Colorimetric Detectionmentioning

confidence: 99%

Gold Nanoparticle-Based Colorimetric Strategies for Chemical and Biological Sensing Applications

et al. 2019

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Gold nanoparticles are popularly used in biological and chemical sensors and their applications owing to their fascinating chemical, optical, and catalytic properties. Particularly, the use of gold nanoparticles is widespread in colorimetric assays because of their simple, cost-effective fabrication, and ease of use. More importantly, the gold nanoparticle sensor response is a visual change in color, which allows easy interpretation of results. Therefore, many studies of gold nanoparticle-based colorimetric methods have been reported, and some review articles published over the past years. Most reviews focus exclusively on a single gold nanoparticle-based colorimetric technique for one analyte of interest. In this review, we focus on the current developments in different colorimetric assay designs for the sensing of various chemical and biological samples. We summarize and classify the sensing strategies and mechanism analyses of gold nanoparticle-based detection. Additionally, typical examples of recently developed gold nanoparticle-based colorimetric methods and their applications in the detection of various analytes are presented and discussed comprehensively.

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“…107,108 The effects of Cl, Br, and I ions in this process has been investigated and all found to have profound etching ability which increases along with redox potential of the ions and their Au-binding strength (Cl -< Br -< I -). 109 It is believed that the halide ions promote gold etching by generating their diatomic species, whose favourable redox potentials provide additional oxidation channels alongside those of H 2 O 2 . 110 The etching of non-seeded, silvermediated, branched AuNPs capped with CTAB by H 2 O 2 in the presence of these three ions saw a continuous, time-dependent blue-shifting of the plasmon band of each nanosystems when exposed to each of the three halides, as well as a dampening in extinction intensity.…”

Section: Etchingmentioning

confidence: 99%

Bespoke nanostars: synthetic strategies, tactics, and uses of tailored branched gold nanoparticles

Siegel

Baker

2021

Nanoscale Adv.

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Halide ions can trigger the oxidative etching of gold nanorods with the iodide ions being the most efficient

Cited by 36 publications

References 36 publications

The Many “Facets” of Halide Ions in the Chemistry of Colloidal Inorganic Nanocrystals

The Many “Facets” of Halide Ions in the Chemistry of Colloidal Inorganic Nanocrystals

Gold Nanoparticle-Based Colorimetric Strategies for Chemical and Biological Sensing Applications

Bespoke nanostars: synthetic strategies, tactics, and uses of tailored branched gold nanoparticles

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