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


Akkopru B., Durucan C.

JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY, vol.43, no.2, pp.227-236, 2007 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 43 Issue: 2
  • Publication Date: 2007
  • Doi Number: 10.1007/s10971-007-1561-7
  • Title of Journal : JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
  • Page Numbers: pp.227-236

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 angstrom whereas the two-step catalyzed silica had an average pore size of 250 angstrom 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 degrees 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.