3. Results and discussion
XRD pattern of the MgAl(CO3)-LDH sample (Figure 1A)
shows clear diffraction peaks at 12.2°, 24.3°, 34.9°, 39.1°, 47.2°,
61.2° and 62.3°, which correspond to (003), (006), (009), (015), (018),
(110) and (113) diffractions of a hydrotalcite
phase.37 To delaminate LDH into monolayer, the
interlayered CO32− were replaced by
NO3− ions. Figure 1B displays the
(003) characteristic peak shifts from 12.2° to 10.2° and the
corresponding layer spacing expands from 0.77 nm to 0.89 nm, which
confirms that the anions between the hydrotalcite layers have been
exchanged from carbonate to nitrate. Figure 1C and 1D are the scanning
electron microscopy (SEM) images of MgAl(CO3)-LDH and
MgAl(NO3)-LDH. It is found that they have similar
regular hexagonal shape, and their particle size distribution is around
1.7−2.5 μm.