title: Scalable preparation of ultrathin silica-coated Ag nanoparticles for SERS application.
abstract: Silica-coated Ag nanoparticles (Ag@SiO2 NPs) have been successfully prepared by a scalable flame spray pyrolysis (FSP) technique with production rate up to 4 g/h in laboratory-scale. The ultrathin SiO2 shell, with a thickness 1 nm, not only effectively avoids the intersintering of Ag nanoparticles core at the high temperature, but also serves as a protective layer of the SERS-active nanostructure. The silica-coated Ag nanoparticles form agglomerates in the large temperature gradient zone, which with several nanometers gaps from each other but not contact. Such an intriguing feature can result in more Raman hot-spots generated at the gaps among Ag core active sites, which will beneficial for the whole SERS substrate enhancement. The results demonstrate that a maximum enhancement factor can reach ~10(5) with a detectable concentration as low as 10(-10) M for rhodamine 6G (R6G) molecules, indicating that the as-obtained unique nanostructure will be a promising candidate for SERS applications.
authors.affiliation: Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science & Technology , Shanghai 200237, China.
authors.forename: Yanjie
authors.initials: Y
authors.lastname: Hu
authors.forename: Yunli
authors.initials: Y
authors.lastname: Shi
authors.forename: Hao
authors.initials: H
authors.lastname: Jiang
authors.forename: Guangjian
authors.initials: G
authors.lastname: Huang
authors.forename: Chunzhong
authors.initials: C
authors.lastname: Li
mesh_terms: D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D049329:Nanostructures / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry / Q000302:isolation & purification*; D012822:Silicon Dioxide / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013499:Surface Properties
chemical_list: D020099:Coated Materials, Biocompatible; D012235:Rhodamines; C026188:rhodamine 6G; D006046:Gold; D012822:Silicon Dioxide