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- Title
Mesostructured Arrays of Nanometer-spaced Gold Nanoparticles for Ultrahigh Number Density of SERS Hot Spots.
- Authors
Lai, Ying‐Huang; Chen, Shiaw‐Woei; Hayashi, Michitoshi; Shiu, Ying‐Jen; Huang, Chiao‐Cheng; Chuang, Wei‐Tsung; Su, Chun‐Jen; Jeng, Hu‐Cin; Chang, Jhe‐Wei; Lee, Yao‐Chang; Su, An‐Chung; Mou, Chung‐Yuan; Jeng, U‐Ser
- Abstract
A novel one-trough synthesis via an air-water interface is demonstrated to provide hexagonally packed arrays of densely spaced metallic nanoparticles (NPs). In the synthesis, a mesostructured polyoxometalate (POM)-silicatropic template (PSS) is first self-assembled at the air-water interface; upon UV irradiation, anion exchange cycles enable the free-floating PSS film to continuously uptake gold precursors from the solution subphase for diffusion-controlled and POM-site-directed photoreduction inside the silica channels. NPs ≈ 2 nm can hence be homogeneously formed inside the silica-surfactant channels until saturation. As revealed via X-ray diffraction, small-angle X-ray scattering (SAXS), grazing incidence SAXS, and transmission electron microscopy, the Au NPs directed by the PSS template are arrayed into a 2D hexagonal lattice with inter-channel spacing of 3.2 nm and a mean along-channel NP spacing of 2.8 nm. This corresponds to an ultra-high number density (≈1019 NPs cm−3) of narrowly spaced Au NPs in the Au-NP@PSS composite, leading to 3D densely deployed hot-spots along and across the mesostructured POM-silica channels for surface-enhanced Raman scattering (SERS). Consequently, the Au-NP@PSS composite exhibits prominent SERS with 4-mercaptobenzoic acid (4-MBA) adsorbed onto Au NPs. The best 4-MBA detection limit is 5 n m, with corresponding SERS enhancement factors above 108.
- Subjects
GOLD nanoparticles; SERS spectroscopy; NANOPARTICLES; X-ray scattering; SURFACE active agents; SOLID solutions
- Publication
Advanced Functional Materials, 2014, Vol 24, Issue 17, p2544
- ISSN
1616-301X
- Publication type
Article
- DOI
10.1002/adfm.201303724