Surface enhanced Raman scattering based on Au nanoparticles/layered double hydroxide ultrathin filmsElectronic supplementary information (ESI) available: Morphology of Au NPs; assembly process and morphological characterization of (Au@PAAS/LDHs)n (n = 0-10) UTFs; Raman tests of LDH nanosheets and drop-casted samples; loading and unloading properties of the UTFs. See DOI: 10.1039/c4tc02714k

Surface-enhanced Raman scattering (SERS) is an effective characterization method which has shown broad applications in the field of detection and identification. In this work, we describe the facile fabrication of SERS ultrathin films (UTFs) based on a two-dimentional architecture via layer-by-layer assembly of hygroscopic sodium polyacrylate (PAAS) modified Au nanoparticles (NPs) and MgAl layered double hydroxide (LDH) nanosheets. The resulting Au@PAAS/LDH UTFs possess a periodic long-range ordered layered structure and dense immobilization of Au NPs within the LDH interlayer microenvironment. The distance of Au NPs in the x-y plane reaches as low as ∼2.16 nm, and thus the coupling of Au-Au NPs enabled an enhanced electromagnetic field and improved SERS effect. For example, a detection limit as low as 10 −9 M could be obtained for Rhodamine 6G. Moreover, the obtained UTFs could be adapted to various solvents and dye molecules, confirming the versatility and the sensitivity of the 2D UTFs. In addition, the UTF exhibits satisfactory reusability and high stability at high temperature and various pH values. Therefore, this work highlights a high-efficiency SERS film material with facile preparation, which guarantees their further application in environmental detection and analysis. Active SERS ultrathin films (UTFs) based on a two-dimensional architecture have been fabricated, and densely immobilized Au NPs leads to an enhanced electromagnetic field and improved SERS effect. These UTFs exhibit versatility and sensitivity in the detection in various analytes.