Characterizing Size and
Porosity of Hollow Nanoparticles:
SAXS, SANS, TEM, DLS, and Adsorption Isotherms Compared
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Abstract
A combination of experimental methods, including transmission
and
grazing incidence small-angle X-ray scattering (SAXS and GISAXS),
small-angle neutron scattering (SANS), transmission electron microscopy
(TEM), dynamic light scattering (DLS), and N<sub>2</sub> adsorption–desorption
isotherms, was used to characterize SiO<sub>2</sub>/TiO<sub>2</sub> hollow nanoparticles (HNPs) of sizes between 25 and 100 nm. In the
analysis of SAXS, SANS, and GISAXS data, the decoupling approximation
and the Percus–Yevick structure factor approximation were used.
Brunauer–Emmett–Teller, <i>t</i>-plot, and
a spherical pore model based on Kelvin equation were applied in the
treatment of N<sub>2</sub> isotherms. Extracted parameters from the
scattering and TEM methods are the average outer and inner diameters
and polydispersity. Good agreement was achieved between different
methods for these extracted parameters. Merits, advantages, and disadvantages
of the different methods are discussed. Furthermore, the combination
of these methods provided us with information on the porosity of the
shells of HNPs and the size of intrawall pores, which are critical
to the applications of HNPs as drug delivery vehicles and catalyst
supports
