**2.2 Preparation of Mg-Al LDH**

In a typical synthesis procedure, Mg-Al LDH was prepared by a facile hydrothermal method. Firstly, 0.05 M of aluminum nitrate and 0.03 M of magnesium chloride were dissolved into 20 ml DDW separately under vigorous magnetic stirring for 10 min. Subsequently, 0.04 M of urea were dissolved into the 10 ml DDW and stirred for 30 min. After that, the precursor and urea solutions were mixed and 0.2 M of NaOH was added to the above solution mixture until the pH of the suspension was reached 12. The entire solution was transferred into a 100 ml Teflon lined stainless-steel autoclave, followed by heating in an oven under 180°C for 24 h. After the reaction was complete, the autoclave was cooled to room temperature. Finally, the sample was centrifuged and washed with DDW water and dried at 80°C for overnight to obtain the final product.

### **2.3 Preparation of ZnO nanoparticles**

ZnO nanoparticles were prepared by the hydrothermal method. In this process, 0.2 M of ZnCl2 were dissolved in 100 ml of DDW, and 0.2 M of NaOH were dissolved in 20 ml of DDW separately under constant stirring. After 10 min stirring the above-mentioned solutions were mixed together, and transferred into a 100 ml Teflon liner stainless-steel autoclave, followed by heating in an oven under 180°C

**Figure 2.**

*Pictorial representation for the formation of g-C3N4\ZnO\Mg-Al LDH 2D/2D LDH tertiary nano-composite [34].*

for 24 h. Later, the autoclave was cooled down naturally. Finally, the obtained solution was centrifuged and washed with DDW water and dried at 80°C for overnight to obtain the final product.

**3.2 Morphological analysis**

*DOI: http://dx.doi.org/10.5772/intechopen.89325*

The surface morphology of the prepared samples was investigated by using FESEM and HRTEM analyses, respectively. The FE-SEM images were obtained by using Zeiss SUPRA-25 and the particle size and morphology of the prepared samples

**Figure 4** shows the FESEM images of (a) Mg-Al LDH, (b) g-C3N4, (c) ZnO and (d) gC3N4\ZnO\Mg-Al LDH ternary nanocomposite samples. The Mg-Al LDH consists of plenty of two-dimensionally structured hexagonal LDHs matrix with a layer by layer assembly. The size of the hexagonal nanoflakes is approximately 200 nm,

Furthermore, the hexagonal formed hydrotalcite-like particles were seen from the HRTEM analysis (**Figure 4d** and **e**) and it concurs well with the morphology

*XRD pattern of (a) Mg-Al LDH, (b) gC3N4, (c) ZnO and (d) g-C3N4\ZnO\Mg-Al LDH ternary*

were analyzed by using HR-TEM – Jeol/JEM 2100, with LaB6 source.

*LDH Ternary Nanocomposites: g-C3N4 Intercalated ZnO\Mg-Al for Superior…*

which indicate the successful exfoliation of a 2D layer.

*3.2.1 FE-SEM analysis*

*3.2.2 HRTEM analysis*

**Figure 3.**

**109**

*nanocomposite [34].*

## **2.4 Preparation of 2D\2D hybrid**

A certain amount of g-C3N4 was dispersed into 20 ml of DDW and ultrasonicated for 30 min. Subsequently, the ZnO\Mg-Al precursor solution was prepared and mixed with ultrasonicated g-C3N4 nanosheets. Again, the mixture was ultrasonicated for 30 min in a beaker to form a homogeneous suspension. After that, the reaction mixture was transferred into a 100 ml Teflon liner stainless-steel autoclave, followed by heating in an oven under 180°C for 24 h. After that, the autoclave was cooled down naturally to ambient temperature. Finally, the sample was centrifuged and washed with DDW water and dried at 80°C for overnight to obtain the final product. **Figure 2** shows the formation of g-C3N4\ZnO\Mg-Al LDH 2D\2D hybrid.
