Mesoporous silica materials were prepared by a sol–gel procedure using
Si(OCH2CH3)4
(TEOS) as the silica source and the non-ionic alkyl-poly(ethyleneoxide) oligomer Brij76
as the structure-directing agent. Pure inorganic hexagonal-like mesostructured
SiO2
powders were obtained after annealing, performed in air between 400 and
600 °C. Upon calcination, the organic template was removed and silica networks with
a different amount of Si–OH groups as well as porous features were prepared.
Ag–SiO2
nanocomposites were obtained by metallation of the mesoporous silica powders with aqueous solutions of silver
acetate. Ag+
ions were chemically grafted on the silica pores by taking advantage of the basic character
of acetate anions and the acidic properties of Si–OH groups. Different silver concentrations
were achieved on the mesostructured silica powders, depending on their former
annealing treatment. For all samples the formation of silver nanoclusters occurred
spontaneously at room temperature. Monodispersed, spherical Ag crystallites,
with an average diameter of a few nanometres, were obtained starting from the
400 °C-treated
silica, whereas clusters with different sizes (3–20 nm) and irregular shapes were grown for metallation of
the 600 °C-heated SiO2
matrix. The sample’s chemical composition was studied by x-ray
photoelectron spectroscopy (XPS) and x-ray excited Auger electron
spectroscopy (XE-AES), whereas the porous features were investigated by
N2
BET adsorption. Information concerning structure and microstructure was obtained by
x-ray diffraction (XRD) and transmission electron microscopy (TEM).
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