Abstract
A two-dimensional layered nanohybrid with a high specific surface area has been prepared by ion exchange reactions between the sodium ions in montmorillonite and the positively charged Zr-coated SiO2 sol particles. The basal spacing increases from 12.5 Å to 26 Å upon intercalation due to the insertion of a SiO2-ZrO2 nano-sol into the interlayer space of montmorillonite. Upon calcining at 300°C, it transforms into a porous nanohybrid with a basal spacing of 22.6 Å. The N2 adsorption-desorption isotherms were characterized as being of type IV according to the BDDT classification, indicating the existence of a large number of micro- and mesopores. From its hysteresis curves, one can classify the nanohybrid as being of the H3 type with slit-shaped pores by the IUPAC classification. The estimated BET specific surface area and average micropore size are about 358 m2 g-1 and 12 Å, respectively, with the latter value is similar to the gallery height of the sample indicating that the SiO2-ZrO2 sol particles are intercalated to form a monolayer. The local structural evolution of the Zr species in SiO2-ZrO2 sol particle has been investigated systematically by X-ray absorption spectroscopy at the Zr K-edge with respect to the calcination temperature. The EXAFS spectroscopic results confirm that the surface of the nano-sized SiO2 sol particles is coated with the Zr species.
Original language | English |
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Pages (from-to) | 557-562 |
Number of pages | 6 |
Journal | Journal of Materials Chemistry |
Volume | 13 |
Issue number | 3 |
DOIs | |
State | Published - 1 Mar 2003 |