“Magic mitt”: Morphologically controllable AuAg@AuAg yolk-shell nanostars with better plasmonic optical properties

• Published in: Journal of alloys and compounds Vol. 844; p. 156134
• Main Authors: Li, Yun-le, Zhu, Jian, Weng, Guo-jun, Li, Jian-jun, Xing, Ting-yang, Zhao, Jun-wu
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.12.2020; Elsevier BV
• Subjects: AuAg@AuAg yolk-shell nanostars; Bimetals; Core-shell structure; Dimers; Electromagnetic fields; Gold-silver alloy; Hot spots; Morphology; Nanospheres; Optical properties; Plasmonic properties; Raman spectra; Rhodamine 6G; Shells; Substrates; Surface-enhanced Raman scattering (SERS); Synthesis; Thickness; Surface-enhanced Raman scattering (SERS); Plasmonic properties; AuAg@AuAg yolk-shell nanostars; Hot spots; Gold-silver alloy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.156134

The yolk-shell structure is a good choice for surface-enhanced Raman scattering (SERS) substrate because the monomer has a dimer property which can create nanogaps with a strong electromagnetic field distribution. However, the existing yolk-shell structures are mostly synthesized on the basis of nanospheres, and there are few reports on the regulation of their optical properties. Compared with other structures, nanostar has emerged as one of the best morphologies for producing SERS because it has more “hot spots” on the branches. This article has synthesized a star-shaped bimetallic yolk-shell structure-AuAg@AuAg yolk-shell nanostar, which has the dual characteristics of the branches and the core-shell structure. It is shaped like a hand with a glove that extends over the hand and only partially covers the fingers, so we also call it “Magic mitt”. And we have adjusted its optical properties by changing the number of branches of the yolk, the thickness of the hollow middle layer and the thickness of the outer shell in this structure. AuAg@AuAg yolk-shell nanostar has shown excellent performance for the improved SERS of rhodamine 6G because of greater coupling between yolk and shell, larger specific surface area, more sufficient particle aggregation, and the blocking effect of the outer shell. The best SERS enhancement factor (EF) of the AuAg@AuAg yolk-shell nanostars for R6G is 1.223 × 106. [Display omitted] •AuAg@AuAg yolk-shell nanostars have the dual characteristic of the branches and the core-shell structure.•Morphology control is regulated in three aspects: number of branches, thickness of hollow middle layer and outer shell.•The excellent SERS activity is mainly due to greater coupling between yolk and shell and more particle aggregationl.•The best SERS enhancement factor (EF) of the AuAg@AuAg yolk-shell nanostars for R6G is 1.223 × 106.