2.1.4. Transmission Electron Microscopy (TEM)

To further understand the structure of the composites, TEM was applied to characterize the microstructure. The TEM images of TH-1, TH-2, TH-3, TH-4, and TH-5 are shown in Figure 4. The black areas show that TiO2 is embedded in the interlayer of hectorite or supported on the surface, which is consistent with the XRD analysis results, indicating that some TiO2 enter the interlayer of hectorite. It can be seen from these images that TiO2 nanoparticles in TH-2 are well distributed in comparison with other samples, which is conducive to photocatalysis. Figure 4c shows that the distance (d) between two crystal faces of TiO2 is 0.353 nm, indicating the existence of an anatase phase structure of TiO2, corresponding to the (101) crystal plane of anatase [29]. The results suggest that the basic

structure of TiO2 cannot be influenced by the hectorite, and the lattice plane of TiO2 in contact with the hectorite surface is the (101) lattice plane.

**Figure 3.** Scanning electron microscopy (SEM) images: (**a**) hectorite, (**b**) TH-1, (**c**) TH-2, (**d**) TH-3, (**e**) TH-4, and (**f**) TH-5.

**Figure 4.** Transmission electron microscopy (TEM) images: (**a**) TH-1, (**b**,**c**) TH-2, (**d**) TH-3, (**e**) TH-4, and (**f**) TH-5.2.1.5. N2 adsorption-desorption isotherms.
