Preparation and microstructure of sol-gel derived silver-doped silica |
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Authors: | Betul Akkopru Caner Durucan |
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Institution: | (1) Department of Metallurgical and Materials Engineering, Middle East Technical University, 06531 Ankara, Turkey |
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Abstract: | Silver-doped silica was prepared by hydrolysis and condensation of tetraethyl orthosilicate (TEOS, Si(OC2H5)4) in the presence of a silver nitrate (AgNO3) solution by two different synthesis methods. In the first synthesis route, sol-gel mixtures were prepared using an acid catalyst. In the second synthesis route, silver-doped silica gels were formed by two-step acid/base catalysis. For the same concentration of silver dopant AgNO3]/TEOS] = 0.015 acid-catalyzed sol-gel formed a microporous silica with an average pore size of <25 Å whereas the two-step catalyzed silica had an average pore size of 250 Å and exhibited a mesoporous structure when fully dried. The differences in the pore size affected the silver particle formation mechanism and post-calcination silver particle size. After calcination at 800 °C for 2 h the acid-catalyzed silica contained metallic silver particles size with an average particle size of 24 ± 2 nm whereas two-step catalyzed silica with the same concentration of AgNO3]/TEOS] = 0.015 contained silver nanoparticles with an average size of approximately 32 ± 2 nm. Mechanisms for silver particle formation and for silica matrix crystallization with respect to the processing route and calcination temperature are discussed. |
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Keywords: | Sol-gel Silica glass Silver nanoparticles Hydrolysis Antibacterial |
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