*3.2. Transmission Electron Microscope (TEM)*

TEM images of nanoparticles of TiO2 and TiO2í*x*N*y*, are reported in Figure 2. Both have almost the same distribution of phases, according to the diffractogram XRD viewed above. The anatase with a hexagonally shaped rounded, has a size about 20 nm (Figure 2a), while rutile shows a hexagonally shape and a size about 60 nm for TiO2 (Figure 2a). In Figure 2b, TiO2í*x*N*y* nanoparticles have an overall size of about 30 nm.

**Figure 2.** TEM images for nanopowders: (**a**) Aeroxide P25 (TiO2) [11]; (**b**) TiO2í*x*N*<sup>y</sup>* (NaBond Technologies Co., Shenzhen, China).
