# Designing Dual-Function Nanostructures for Water Purification in Sunlight
## 3 Results and Discussion  
### Powder X-ray Diffraction  
The powder X-ray diffraction patterns of the prepared graphene, Zn-Al LDHs and series of Zn-Al-GO were observed in Figure 2. The prepared graphene showed the main peak at 2-theta 26.7\({}^{\circ}\) and d-spacing of 0.33 nm agreeing with the reflection in the (002) plane of aromatic layers of the graphite as seen in Figure 2e. In addition, the reflection in the (100) plane of aromatic layers of graphite was observed as a weak peak at 42.9\({}^{\circ}\). The reflection of plane (100) peak is due to the condensation degree of the aromatic carbon ring. The orientation of the aromatic carbon ring in three-dimensional arrangement could be determined by the reflection of plane (002) [19; 20]. The other peaks observed at 2-theta 21.8\({}^{\circ}\) and 24.2\({}^{\circ}\) in Figure 2e represent the modified layers of graphene. The X-ray diffraction pattern of the pure Zn-Al LDH is exhibited in Figure 2a. A series of clear and symmetric peaks occurring at 2-theta of 11\({}^{\circ}\), 23\({}^{\circ}\), 34\({}^{\circ}\), 39.24\({}^{\circ}\), 59.8\({}^{\circ}\)and 60.7\({}^{\circ}\) were assigned to the reflection of planes (003), (006), (012), (015), (110) and (113) of Zn\({}_{0.7}\)Al\({}_{0.3}\)(OH)\({}_{2}\)(CO\({}_{3}\))\({}_{0.15}\)\(\times\)H\({}_{2}\)O (JCPDS file No. 48-1022) [1,21], indicating that the nanolayered structure of LDHs was successfully prepared. The basal spacing d-value of the (003) peak is 0.76 nm, which referred to the intercalation of carbonate into the interlayer spacing of LDHs [22, 23, 24]. The unit cell parameters (a and c) can be obtained from a = 2d(110) and c = 3d(003); respectively. The values were 0.31 nm and 2.28 nm agreeing with our results, which previously reported for LDHs [1]. To understand the nanostructures of Zn-Al-GO, Figure 2b-d display XRD patterns of the composites Zn-Al-GO1, Zn-Al-GO2 and Zn-Al-GO3; respectively. In Figure 2b, two series of layered structures were observed for the Zn-Al-GO1 composite. The first series was 0.75 nm, 0.37 and 0.25 nm. The second series was 0.68 nm, 0.33 nm and 0.23 nm. These spacings agree with the characteristic peaks of Zn-Al LDHs corresponding to (003), (006) and (009) planes. The characteristic peak of the graphene oxide may have overlapped with the main peak of LDHs at 2-theta 11.9\({}^{\circ}\) with the d-spacing 0.74 nm [25]. It means that two types of LDHs were grown and interacted with the layers of graphene oxide. The presence of graphene oxide caused narrowing for the d-spacing among the layers of LDHs because of grown of LDH over the layers of graphene oxide [26]. In addition, presence of graphene oxide caused appearance of new phase at 0.45 nm and 0.30 nm. These peaks may be due to reflections of planes (006) and (009) for new phase of LDHs. This new phase based on incorporating and interacting the nanolayers of LDHs with single nanosheets of graphene oxide to look like sandwich-type structure of LDHs. Where, the thickness of this new phase is summation of the single nanosheet of both LDHs and graphene oxide; 0.48 nm and 0.42 nm; respectively [27]. This new phase showed continuous reflections agreeing with 2d\({}_{006}\) = 3d\({}_{009}\) (2 \(\times\) 0.45 nm = 3 \(\times\) 0.3 nm). By increasing the percentage of GO, only one kind of the layered structures of LDHs was observed in the X-ray diffraction patterns as shown in Figure 2c,d. The sharp and symmetric reflections of the XRD patterns of both Zn-Al-GO2 and Zn-Al-GO3, which  
Figure 2: X-ray diffraction of: (**a**) Zn-Al layered double hydroxide (LDH), (**b**) Zn-Al-GO1, (**c**) Zn-Al-GO2, (**d**) Zn-Al-GO3 and (**e**) The prepared graphene. observed at 11.8\({}^{\circ}\), 24.6\({}^{\circ}\), 34.7\({}^{\circ}\), 37.4\({}^{\circ}\), 39.3\({}^{\circ}\), 60.3\({}^{\circ}\), and 61.6\({}^{\circ}\), agree with the basal spacing of the layered crystalline Zn-Al LDHs phase d\({}_{003}\), d\({}_{006}\), d\({}_{012}\), d\({}_{009}\), d\({}_{015}\), d\({}_{110}\) and d\({}_{113}\); respectively.