Additional file 1: Figure S1. of Silica Cladding of Ag Nanoparticles for High Stability and Surface-Enhanced Raman Spectroscopy Performance

The cross-sectional views of Ag@SiO2 nanostructures with the thickness of SiO2 layers vary from 0 to 50 nm. Figure S2. The corresponding energy spectrum of Ag@SiO2 nanostructures with the thickness of SiO2 layers vary from 0 to 50 nm. Figure S3. Characterization of the reproducibility of Ag@SiO2 nanostructure (a) Raman spectra of CV on different Ag@SiO2 substrates (b). The intensity curves of CV at 1174 and 1620 cm−1 absorbed on the substrates. Figure S4. A water droplet falling on (a) the Ag film; (b) the Ag@SiO2 film; (c) Raman spectra of CV molecules on Si (1)/Si coated with 10-nm SiO2 wafer (2). Figure S5. Morphology characterizations of the Ag@SiO2 nanostructures after immersing in deionized water for 0, 0.5, 1, 5, 10, 24, and 72 h and 15 days with the thicknesses of SiO2 are (a) 0 nm (b) 10 nm, and (c) 20 nm. (DOC 19191 kb)