PERSONAL DE APOYO
MARCHI Maria Claudia
congresos y reuniones científicas
Título:
MESOPOROUS OXIDES: WHAT CAN WE DO WITH THEM?
Autor/es:
E. OTAL; V. DELLA SAVIA; M.C. MARCHI; S.A. BILMES; G. SOLER-ILLIA
Lugar:
Buenos Aires
Reunión:
Workshop; Seven J. J. Giambiagi Winter School, ?New trends in complex materials?; 2005
Institución organizadora:
FCEN
Resumen:
Since the development of the first
mesoporous silica (Beck et al, 1992) a great variety of silica and transition
metal mesoporous oxides have been synthesised by following different chemical
routes. These oxides can be obtained as xerogels, powders, films or fibers with
high surface areas (200-1000 m2/g), a variety of mesostructures (2D- or 3D-
hexagonal, cubic, local order), pore diameters (3-12 nm) and amorphous or
nanocrystalline walls. This versatility makes this kind of materials
interesting for a lot of possible applications such as optical, electronics,
catalysis, sensing, separation, etc. One step beyond, is to modify the oxide
matrix with organic functions, in order to obtain a hybrid mesoporous
composite, which combines the advantages and properties of mesoporous oxides and
hybrid materials. The regular pore size and surface control also makes the pore
systems ideal candidates for nanoparticle (NP) template, leading to NP@oxide
composites, which can be tailored to combine the properties of two kinds of
nanometric size elements, which are in intimate contact through an extended
interface, all combined in a robust matrix. These two procedures leads to
materials with different properties and potential applications than the pure
mesoporous oxides. In this work, we present examples of multifunctional
mesoporous films, created by adding organic functions to MP silica or
transition metal oxides (TiO2, ZrO2 and Si/Ti, Si/Zr mixed oxides) either by
co-condensation (?one pot?) or post synthesis grafting. We also present two
alternative ways in order to obtain NP@oxide nanocomposites. CdS@SiO2 and
CdS@TiO2 were obtained by chemical precipitation, and Au@TiO2 or Ag@TiO2 by
photochemical or electrochemical reduction of the cations. All materials were
supported as films, and were fully characterized by (HR)TEM, SEM, EDS, SAXS,
XRD, FTIR, UV-Vis absorption, fluorescence and electrochemical methods.