Preparation and microstructure of sol-gel derived silver-doped silica

• Published in: Journal of sol-gel science and technology Vol. 43; no. 2; pp. 227 - 236
• Main Authors: AKKOPRU, Betul, DURUCAN, Caner
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.08.2007; Springer Nature B.V
• Subjects: Acids; Catalysis; Chemical synthesis; Chemistry; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Crystallization; Exact sciences and technology; General and physical chemistry; Nanoparticles; Particle size; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Pore size; Porosity; Roasting; Silica gel; Silicon dioxide; Silver; Sol-gel processes; Tetraethyl orthosilicate; Nanoparticle; Sol-gel; Glass; Transition metal; Antibacterial; Silica; Hydrolysis; Silica glass; Silver; Sol gel process; Preparation; Antibacterial agent; Microstructure; Silver nanoparticles
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-007-1561-7

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.