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Authors Tzounis, L. ; Contreras-Caceres, R. ; Schellkopf, L. ; Jehnichen, D. ; Fischer, D. ; Cai, C. ; Uhlmann, P. ; Stamm, M.
Title Controlled growth of Ag nanoparticles decorated onto the surface of SiO2 spheres: A nanohybrid system with combined SERS and catalytic properties
Date 28.02.2014
Number 38922
Abstract A versatile water-based method for depositing silver nanoparticles (Ag NPs) with controllable and uniform metal size onto the surface of silica (SiO2) spheres is reported. The hybrid particles exhibited a raspberry-like morphology, and their potential for SERS and catalytic applications has been demonstrated. SiO2 spheres (~120 nm) were synthesized first and modified with polyethyleneimine (PEI) to introduce amine surface functionalities. The amine groups were coordinated with silver ions (Ag+) and reduced to Ag seeds (~4 nm), uniformly distributed onto the SiO2 surface (SiO2@Ag-seed).In order to improve the optical responses and catalytic activity of SiO2@Ag-seed system, two subsequent silver growth steps were performed. The diameter of Ag seeds was increased to 12 and 19 nm, respectively, hereafter denoted as SiO2@Ag-1 and SiO2@Ag-2. The immobilization and controlled growth of Ag NPs was confirmed by UV-vis spectroscopy, scanning and transmission electron microscopy (SEM, TEM). All specimens displayed satisfactory SERS activity increasing with the Ag NP size, showing clear Raman peaks of Rhodamine 6G (R6G) at very low concentration. The SiO2@Ag particles were also tested and compared for their catalytic efficiency towards the reduction of 4-nitrophenol (4-Nip) by NaBH4. The principal advantages of this study lie on the ability to tune the Ag NP size, the long-term colloidal stability of all fabricated SiO2@Ag systems in aqueous media, and the limited use of hazardous chemicals and pollutant organic solvents during the synthetic process.
Publisher RSC Advances
Wikidata
Citation RSC Advances 4 (2014) 17846-17855
DOI https://doi.org/10.1039/C4RA00121D
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