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Effects of Strain and Kinetics on the H2O2-Assisted Reconstruction of Ag-Au-Ag Nanorods.

ABSTRACT: Morphology of Ag nanocrystals (NCs) is essential to the NC application in catalysis, optics, and as antibacterial agents. Therefore, it is important to develop synthetic methods and understand the evaluation of NC morphology in different chemical environments. In this study, we report interesting findings of the morphological change of fivefold-twinned Ag-Au-Ag nanorods (NRs) under the effect of H2O2 both as an oxidant (etchant) and a reductant. At low H2O2 concentration, the reconstruction of Ag-Au-Ag NRs was dominated by the growth along the longitudinal direction of NRs. With the increase of H2O2 concentration, the reconstruction also occurs in the transverse direction, and a clear change in particle morphology was observed. We further systematically studied the mechanism of the reaction. The results showed that the transition of the morphology was a two-step process: (1) the etching of Ag on the seeds and (2) the reduction of Ag2O. In the second step, the reaction kinetics was highly affected by H2O2 concentration. At low H2O2 concentration, the growth mainly occurs along ?110?. However, at high H2O2 concentration, the reduction of Ag was not facet-selective. Using the developed method, we can prepare various bimetallic NCs (high aspect ratio NRs with abundant pinholes, nanoplates, and other NCs). The effect of the reconstruction process on the surface-enhanced Raman scattering (SERS) performance of NCs was investigated.

SUBMITTER: Hao H

PROVIDER: S-EPMC7450662 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Effects of Strain and Kinetics on the H2O2-Assisted Reconstruction of Ag-Au-Ag Nanorods.

Hao Hui H Yang Yinliang Y Zou Chao C Chen Wei W Wen Haihong H Wang Wei W Yang Yun Y

Langmuir : the ACS journal of surfaces and colloids 20200811 33

Morphology of Ag nanocrystals (NCs) is essential to the NC application in catalysis, optics, and as antibacterial agents. Therefore, it is important to develop synthetic methods and understand the evaluation of NC morphology in different chemical environments. In this study, we report interesting findings of the morphological change of fivefold-twinned Ag-Au-Ag nanorods (NRs) under the effect of H2O2 both as an oxidant (etchant) and a reductant. At low H2O2< ...[more]

PMID: 32787127

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Project description:Compared to inorganic mercury (Hg2+), methyl-mercury (CH3Hg+) and ethyl-mercury (C2H5Hg+) (organic mercury) not only have a much stronger toxicity but also are more easily accumulated by marine organisms to produce bioamplification. Therefore, the simultaneously onsite detection of Hg2+ and organic mercury is of great significance to ensure the safety of seafood, and it is also a hard challenge. We designed a T-rich aptamer, HT7, for specifically recognizing Hg2+ and organic mercury and developed a multicolor aptasensor for simultaneous discrimination and detection of Hg2+ and organic mercury with only bare-eye observation using HT7 as a recognition probe and gold nanorods (AuNRs) as a signal. In the presence of Hg2+ and Ag+, Hg2+ preferentially and specifically bind with HT7 immobilized on AuNRs surface and induce the formation of a monolayer Ag/Hg amalgam on the AuNRs surface after reduction, resulting in a change in color from orange to faint purple and a corresponding shift in the absorption peak from 820 to 730 nm in the solution. However, in the presence of CH3Hg+ or C2H5Hg+ and Ag+, CH3Hg+ or C2H5Hg+ preferentially bind with HT7 immobilized on the AuNRs surface and induce the formation of a monolayer Ag0 on the AuNRs surface after reduction, which results in the change in color from orange to atrovirens and the corresponding shift in the absorption peak shift from 820 to 670 nm in the solution. Thus, the inorganic and organic mercury (total of CH3Hg+ and C2H5Hg+) can be specifically discriminated and detected by only bare-eye observation. The method can be used to simultaneously detect inorganic and organic mercury in seawater by the bare-eye observation with a visual detection limit of 2.0 ppm for Hg2+ and 10.0 ppm for organic mercury. The success of this study is a useful enlightenment to develop an instrument-free method for an onsite detection of trace inorganic and organic mercury in environment by a bare-eye observation, although the sensitivity of the method is relatively low.

Dataset Information

Effects of Strain and Kinetics on the H2O2-Assisted Reconstruction of Ag-Au-Ag Nanorods.

Publications

Effects of Strain and Kinetics on the H<sub>2</sub>O<sub>2</sub>-Assisted Reconstruction of Ag-Au-Ag Nanorods.

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