Ag2O@Ag core-shell structure on PMMA as low-cost and ultra-sensitive flexible surface-enhanced Raman scattering substrate

We report a simple method to fabricate Ag2O@Ag core-shell nanostructure employed as SERS (surface enhanced Raman scattering) active substrate. The Ag2O shell was fabricated via the oxidation of AgNPs with the assist of laser irradiation in atmosphere. In this way, the prepared Ag2O@Ag hybrid system possesses ultrasensitivity, homogeneity, reproducibility and chemical stability by virtue of ultra-thin inner shell. The minimum detectable concentration of R6G was presented as low as 10(-11) M. The enhancement factor of Ag2O@Ag core-shell nanostructure using R6G as probe molecules was found to be as high as 6 x 10(7). Furthermore, the flexible Ag2O@Ag/PMMA SERS substrate were first presented and the SERRS (surface enhanced resonance Raman scattering) spectra of the R6G on this substrate were investigated. The characteristic peaks of R6G with concentration from 10(-5)-10(-11) M can be also easily observed by detecting from both sides of the flexible substrate. A good linear response between SERRS intensity and R6G concentration from 10(-5) to 10(-11) M was obtained. For practical application, the Ag2O@Ag/PMMA hybrids flexible SERS substrate was used for real-time and in-situ detection of chlor-pyrifos with 10(-7) M on cucumber and apple peels. These results are exactly consistent with the DFT simulation on chlorpyrifos pesticide and confirm that the Ag2O@Ag/PMMA hybrids flexible SERS substrate is highly promising for food safety field in the future. (C) 2016 Elsevier B.V. All rights reserved.