## 2 Results and Discussion
### Particle Characterization  
One of the main objectives of this study was the development and investigation of some hybrid composites containing ZnO-doped particles intended for photochemical purification of wastewater. Besides the synthesis of the monomer, ZnO and ZnO-SnO\({}_{2}\) particles were prepared by the method detailed in the Experimental section. Figure 2a shows typical X-ray diffraction (XRD) patterns for the obtained ZnO and ZnO-SnO\({}_{2}\). The pure ZnO sample displayed distinct peaks at 20 = 31.8\({}^{\circ}\), 34.4\({}^{\circ}\), 36.2\({}^{\circ}\), 47.6\({}^{\circ}\), 56.6\({}^{\circ}\), 62.9\({}^{\circ}\), 68\({}^{\circ}\), 69.2\({}^{\circ}\), 66.4\({}^{\circ}\), 72.6\({}^{\circ}\), 77.1\({}^{\circ}\) corresponding to (100), (002), (101), (102), (110), (103), (200), (112), (201), (004), and (202) planes, with no evidence for any secondary phase or possible impurity, which was in line with the standard hexagonal (wurtzite) ZnO powder (standard JCPDS card no. 80-0075) [49]. The XRD spectrum of ZnO-SnO\({}_{2}\) exhibited broad diffraction peaks at 26.1\({}^{\circ}\), 34.3\({}^{\circ}\), and 52.2\({}^{\circ}\), which could be attributed to the (110), (101), and (211) diffraction planes characteristic for the tetragonal structure of SnO\({}_{2}\). The characteristic peaks of ZnO could not be accurately distinguished with respect to those of SnO\({}_{2}\). Thus, it could be assumed that the ZnO-SnO\({}_{2}\) sample was in an amorphous phase [50; 51; 52]. Figure 2b illustrates the Raman spectra of the ZnO and ZnO-SnO\({}_{2}\) particles at room temperature. The peaks recorded for the ZnO sample at 101, 277, 331, 379, 438, and 580 cm\({}^{-1}\) could be associated with the hexagonal ZnO structure, the spectrum being almost identical to the reference one, reported in the literature [53; 54]. On the other hand, significant peak shifts could be observed for the ZnO-SnO\({}_{2}\) sample as compared to the pure ZnO, changes that are probably caused by the appearance of heterostructures between the ZnO and SnO\({}_{2}\). For this sample, the peaks were found at 71, 404, 667, and 580 cm\({}^{-1}\), the last one characteristic for ZnO being in the form of a small shoulder [47; 48]. The peak at 667 cm\({}^{-1}\) could be associated with the oxygen vacancies of SnO\({}_{2}\) nanocrystal surface defects [55; 56]. The FTIR analysis of undoped ZnO and ZnO-SnO\({}_{2}\) particle samples was also performed (Figure S2a, SI). The results revealed that the peaks registered at 3435 cm\({}^{-1}\) and 1637 cm\({}^{-1}\) for ZnO and 3400 cm\({}^{-1}\) and 1639 cm\({}^{-1}\) for ZnO-SnO\({}_{2}\) originated from the adsorbed H\({}_{2}\)O molecules on the particles surfaces. The bands at 516 and 393 cm\({}^{-1}\) could be associated with the absorptions of the Zn-O bond [57]. The incorporation of Sn to ZnO nanostructures led to the appearance of a large band, much intense compared to that of the pure sample at 560 cm\({}^{-1}\), which could be attributed, according to the literature data, to the Sn-O bond vibration [58]. Figure 1: \({}^{1}\)H NMR (**a**) and \({}^{13}\)C NMR; (**b**) spectra of N,N-(diisopropylcarbamoyloxy)ethyl methacrylate (N-MA) in CDCl\({}_{3}\). Figure 3 illustrates the SEM and TEM micrographs of ZnO and ZnO-SnO\({}_{2}\) particles. The SEM images (Figure 3a) showed that the ZnO sample was in the form of flowers (or stars) with homogeneous rod shape. TEM analysis (Figure 3b) supported this observation, demonstrating that ZnO particles were in the form of homogeneous rods crowded in floral geometries with lengths of 2-4 \(\upmu\)m and widths between 30 and 100 nm. For ZnO-SnO\({}_{2}\) particles, the SEM images (Figure 3c) evidenced their form of cubes with sides of approximately 350 nm, as calculated from the TEM analysis (Figure 3d). Compared to the shape of ZnO nanoparticles doped with SnO\({}_{2}\), reported in the literature [7,29,30], which have irregular or spherical shapes, our particles displayed well-defined cubic forms, never seen before.