3.4.1. XRD

XRD analysis was used to identify fresh catalyst crystalline structure and to study transformations that might have occurred on this crystalline structure during and after activation, DR reactions, and CC reactions. The diffractometer used was Philips X'Pert PRO equipped with a Cu tube as its X-ray source and a Ni filter that was used to only let through Kα1 radiations from Cu (1.5418 Å) produced at 40 kV and 50 mA. The anti-dispersion slit was set at 1/2 and the diverged slit at 1/4. The analysis was carried out with a scanning angle of 2θ ranging from 15◦ to 90◦.

Crystallite size can be calculated using Scherrer Equation:

$$\mathbf{L}\_{\mathbf{c}} = \begin{array}{c} \mathbf{K} \times \lambda \\ \hline \mathbf{d} \times \cos \ \theta \end{array}$$

Lc—crystallite size (nm); K—0.9; λ—1.5418 (Å) for Cu Kα1; d—FHMW (full width at half maximum) calculated using Origin software (nm); <sup>θ</sup>—angle (rad).

#### 3.4.2. SEM and EDX

Scanning electron microscopy was used to characterize CNF and to study their morphology. The microscope used was a Hitachi Cold FE SU-823000 characterized by a 0.5 nm resolution at 30 kV and 3 nm resolution at 0.05 kV. It was equipped with a secondary electron (SE) lower detector, an SE/backscattered electron (BSE) upper detector, an SE/BSE top detector with energy filtration of BSE, a five quadrant BSE detector, a STEM (scanning transmission electron microscopy) detector for bright/dark fields, and a drift silicon detector energy dispersive X-ray spectrometry (SDD-EDS) detector, which was used to study the elemental composition and mapping of the sample.

#### 3.4.3. TEM Coupled with EDX and Selected Area Electron Di ffraction (SAED)

The microscope used was the Jeol JEM-2100F analytical transmission electron microscope equipped with a field e ffect gun operating at an acceleration voltage of 200 kV. Capable of imaging resolutions of 0.1 nm, this microscope was also equipped with an EDX spectrometer for chemical analysis. It also allowed the evaluation of crystallography using electron di ffraction.
