*2.2. Samples Characterizations*

The compounds were characterized by means of the following techniques: thermo gravimetric analysis (TGA), X-ray di ffraction analysis on powders (PXRD), field emission scanning electron microscope analysis (FESEM), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma optical emission spectroscopy (ICP-OES) chemical analysis.

## 2.2.1. Thermo Gravimetric Analysis

In order to perform the TGA, about 30–50 mg of the dried powdered LDH was placed in alumina open crucibles; the measurements were carried out by means of a H/LABSYSEVO-1A SETARAM apparatus (Setaram, Caluire, France), at a heating rate of 5 ◦C min−<sup>1</sup> under argon flux of 30 mL min−1.

#### 2.2.2. Field Emission Scanning Electron Microscope Analysis

To investigate the morphology and the structure of the synthesized compounds, an FESEM analysis has been performed. The samples were adhered on a conductive resin support, then analyzed by applying an acceleration voltage of 5 kV for 50 s, and a cobalt standard was used for the calibration.

#### 2.2.3. Powder X-ray Di ffraction

To determine the crystal structures and to calculate the lattice parameters of the phases, PXRD analysis was carried out by the vertical di ffractometer X'Pert MPD (Philips, Almelo, The Netherlands) equipped with a Cu tube (K α1 wavelength: 1.5406 Å). The samples were grounded in an agate mortar. The patterns were collected between 10◦ and 100◦ 2θ with a step of 0.001◦ and measuring time of 50 s/step. The indexing of the obtained di ffraction data was performed by a comparison with the literature or calculated data (the program Powder Cell-version1999 [20]).
