## 3 Results and Discussion
### Structure and Morphology by Means of XRD, HRTEM, and Raman Analyses
#### 3.1.2 HRTEM Images  
The MoS\({}_{2}\)/TiO\({}_{2}\) n-sh (36 mL MoS\({}_{2}\)) sample obtained by the ex situ method was TEM and HRTEM imaged, as shown in Figure 2a-d. TiO\({}_{2}\) nanosheets with lateral dimensions in the 50-200 nm range (Figure 2a) and thicknesses of about 30-40 nm (Figure 2b) are observed from the lower resolution TEM images. In the HRTEM image in Figure 2c, where nanoparticles are perpendicularly oriented to the electron beam, the TiO\({}_{2}\) nanosheets are highly crystalline and expose well-defined interference fringes, 3.53 A spaced due to anatase (101) planes [43]. Cavities with rectangular shape, resulting from the nanosheet preparation, can be observed by the variation in intensity across different regions in the nanoparticles. A small nanoparticle with lateral dimension of 20 nm and 5 nm in thickness, exposes 6.5 A spaced interference fringes that are disrupted in the center (Figure 2d). Such a nanoparticle of irregular shape can be safety assigned to a MoS\({}_{2}\) slab with the stacking number \(>\)5-6 [44].  
The MoS\({}_{2}\)/TiO\({}_{2}\) n-sh (Mo 3 wt.%) sample obtained by the in situ method is TEM and HRTEM imaged at different magnifications in Figure 3a-d. TiO\({}_{2}\) nanosheets have a prevalent orientation perpendicular to the electron beam (Figure 3a), thus exposing their basal sizes in the 30-100 nm range, although a few nanosheets expose their thicknesses of about 20-30 nm as obtained from remarkable image contrast (Figure 3b). The selected regions in Figure 3a,b are HRTEM imaged in Figure 3c,d, where regular interference fringes, 3.53 A spaced, that correspond to (101) planes of anatase are decorated with more irregular fringes. Such fringes have spacings of about 6.5-6.7 A and can be assigned to thin MoS\({}_{2}\) slabs at the surface of anatase nanoparticles [41; 42]. Furthermore, a stacking number of 3 \(\pm\) 2 layers and basal sizes of 2-10 nm can be observed. It is worthy of attention that the MoS\({}_{2}\) slabs as obtained by the in situ preparation appear to be thinner and more defective (i.e., basal plane interruptions, more curved structures decorating the anatase facets) with respect to the slabs obtained by the ex situ preparation, despite the higher MoS\({}_{2}\) concentration.  
Figure 1: XRD patterns of TiO\({}_{2}\) anatase nanosheet (n-sh) pre-treated at 873K (black line), of MoS\({}_{2}\)/TiO\({}_{2}\) n-sh prepared by the ex situ method (blue line), of MoS\({}_{2}\)/TiO\({}_{2}\) n-sh obtained by the in situ approach (red line), and of pure bulk MoS\({}_{2}\) used as a reference material (grey line). Asterisks (*) show the weak diffraction features typical of MoS\({}_{2}\).  
Figure 3: TEM and HRTEM images obtained at different magnifications of MoS\({}_{2}\)/TiO\({}_{2}\) n-sh prepared by in situ method: (**a**) TEM image of MoS\({}_{2}\)/TiO\({}_{2}\) n-sh aggregates; (**b**) enlarged view of the selected region in panel (**a**); (**c**,**d**) HRTEM images at two different levels of magnification of the selected region in panel (**b**), where regular interference fringes, 3.53 Å spaced, that correspond to (101) planes of anatase are decorated with more irregular fringes due to MoS\({}_{2}\) nanoparticles.  
Figure 2: TEM and HRTEM images obtained at different magnifications of MoS\({}_{2}\)/TiO\({}_{2}\) n-sh prepared by the ex situ method: (**a**) TEM image of TiO\({}_{2}\) nanosheets aggregates; (**b**) enlarged view of the selected region in panel (**a**); (**c**) HRTEM image of TiO\({}_{2}\) nanosheets exposing well-defined interference fringes; (**d**) HRTEM image of MoS\({}_{2}\) slab with the stacking number >5–6.