Abstract
[Display omitted]
► We determined the structure of the first tri-continuous mesoporous silica, IBN-9. ► The structure contains three identical and inter-woven channels. ► The silica wall follows a branched hexagonal minimal surface. ► The structure was determined by electron crystallography, from three HRTEM images. ► The procedures for structure determination of unknown structures are described.
High resolution electron microscopy (HRTEM) has unique advantages for structural determination of nano-sized porous materials compared to X-ray diffraction, because it provides the important structure factor phase information which is lost in diffraction. Here we demonstrate the structure determination of the first tri-continuous mesoporous silica IBN-9 by electron crystallography. IBN-9 has a hexagonal unit cell with the space group
P6
3/
mcm and
a
=
88.4
Å,
c
=
84.3
Å. HRTEM images taken along three main directions, [0
0
1],
[
1
1
¯
0
]
and [1
0
0] were combined to reconstruct the 3D electrostatic potential map, from which the tri-continuous pore structure of IBN-9 was discovered. The different steps of structure determination of unknown mesoporous structures by electron crystallography are described in details. Similar procedures can also be applied for structure determination of other porous and nonporous crystalline materials.