Symmetry Breaking in Seed-Mediated Silver Nanorod Growth Induced by Dimethyl Sulfoxide

Abstract

Engineering symmetry breaking in seed-mediated growth is a fundamental challenge to produce colloidal nanocrystals with controlled morphologies and properties. In this work, we show a simple, aqueous approach to breaking the inversion symmetry of silver nanorods by restricting growth to one end of the pentatwinned gold bipyramid seed. Controlled addition of dimethyl sulfoxide (DMSO) allows us to tune both the symmetry and the length and width of the objects.Simulations and experiments demonstrate the adsorption of DMSO, which displaces interfacial water, reduces binding of surfactant and chloride ions at the gold surface, and slows down the deposition kinetics of silver. Besides showing the potential of DMSO for controlling the synthesis of complex nanostructures, this work opens new perspectives for the study of the physical properties of non-centrosymmetric nanoparticles, e.g. by controlling their plasmon modes and their second-harmonic generation efficiency.

Symmetry-Reduced Metal Nanostructures Offer New Opportunities in Plasmonics and Catalysis

“…, C 5 v symmetry, respectively, depending on the presence of the cosolvent dimethyl sulfoxide (DMSO). Specifically, the NPs with noncentrosymmetric seeds were achieved by the addition of DMSO to the synthesis, which is hypothesized to disrupt the micellization of CTAC, causing the overgrowth of Ag to be restricted primarily to one side of the bipyramidal Au seed . The LSPR of the NPs with noncentrosymmetric seeds was blue-shifted compared to the NPs with centrosymmetric seeds (Figure F) .…”

“…Specifically, the NPs with noncentrosymmetric seeds were achieved by the addition of DMSO to the synthesis, which is hypothesized to disrupt the micellization of CTAC, causing the overgrowth of Ag to be restricted primarily to one side of the bipyramidal Au seed . The LSPR of the NPs with noncentrosymmetric seeds was blue-shifted compared to the NPs with centrosymmetric seeds (Figure F) . This example highlights how changing the symmetry of core@shell NPs through the position of their seeds, the LSPR of metal NPs can be fine-tuned.…”

“…The asymmetric passivation of seeds promotes growth on certain parts of the seeds while others become more strongly passivated by Ag, promoting the 1D growth observed in nanorod formation (Figure A). , Overgrowth of a second material on a metal seed can introduce compositional and architectural complexity inherent to the spatial relationship between the seed and depositing material . For example, rodlike particles have an additional degree of tunability by modifying the position of the metal seed in the interior of the resulting nanorod upon deposition of a secondary material, i.e., centrosymmetric versus noncentrosymmetric (Figure B) . Additionally, asymmetric passivation can be achieved through controllably coating part of a seed with an unreactive protecting group such as collapsed polymer or silica and growing a secondary material on the exposed metal surface. ,,− Polymers on NP seeds have promoted formation of NPs with nanogaps and chirality through seed-mediated growth. , …”

“…Copyright 2021 American Chemical Society. Parts D–F are adapted with permission from ref . Copyright 2021 American Chemical Society.…”

“…For example, the location of the metal seed in core@shell metal NPs can affect the LSPR . Shown in Figure D,E are TEM images of Ag nanorods synthesized from Au nanobipyramidal seeds by reducing AgNO 3 with ascorbic acid in the presence of cetyltrimethylammonium chloride . The seeds can be positioned in a centrosymmetric manner, i.e.…”