Site-specific Ag coating on concave Au nanoarrows by controlling the surfactant concentration

Dashen Dong, Qianqian Shi, Debabrata Sikdar, Yunmeng Zhao, Yiyi Liu, Runfang Fu, Malin Premaratne, Wenlong Cheng

Research output: Contribution to journalArticleResearchpeer-review

3 Citations (Scopus)

Abstract

The ability to control the site-selective deposition of a noble metal with nanoscale accuracy is vital for the synthesis of well-defined heterogeneous core-shell bimetallic nanoparticles for various applications ranging from nanophotonics to catalysis. Here, precise site-specific Ag coating onto concave gold nanoarrows (GNAs) is reported by tuning the concentration of the surfactant-cetyltrimethylammonium chloride (CTAC). Three distinct nanocoating structures, namely, anisotropic coating, middle coating, and conformal coating are obtained, which are achieved under low, medium and high CTAC concentrations, respectively. The site-specific nanoscale coating on GNAs is proved by scanning transmission electron microscopy imaging in conjunction with the elemental mapping. The CTAC concentration-dependent, facet-specific passivation may be the cause for the three distinct nanoparticles obtained. The morphology differences resulted in discrete plasmonic features, and a linear relationship between the resonance peak and the CTAC concentration is found for the conformal-coated GNAs. We further fabricate free-standing monolayer nanosheets out of the three kinds of nanoparticles, which display strong shape-dependent SERS enhancements.

Original languageEnglish
Pages (from-to)940-946
Number of pages7
JournalNanoscale Horizons
Volume4
Issue number4
DOIs
Publication statusPublished - 1 Jul 2019

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