EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

A series of Al-doped ZnO nanoparticles with different Al content was synthesized via a solvothermal route, and employed as photocatalysts for the degradation of the organic dye Rhodamine B in liquid phase under UV and visible-light irradiation. The amount of dopant incorporated into the final solid was quantified by inductively coupled plasma-optical emission spectrometry (ICP-OES). It showed that the experimental Al content represents about the 65% of the nominal value. The morphology and the size distribution of the nanoparticles were evaluated by transmission electron microscopy (TEM); the synthesis produced quasi-spherical nanoparticles for both undoped ZnO and Al-doped ZnO. The nanoparticles exhibited diameters ranging between 10 and 60 nm. To investigate and determine any possible effects of the dopant on the zinc oxide structure, additional characterization techniques have been used. The X-ray powder diffraction (XRPD) patterns of the nanomaterials matched with the hexagonal wurtzite crystal phase. A secondary crystalline phase is also observed. In the Fourier transform infrared (FT-IR) spectra a pronounced absorption between 800 and 3000 cm-1 is observed for all the Al-doped ZnO semiconductors, while is absent for the undoped material. The appearance of this absorption in the MID infrared can be attributed to plasmon absorption in the case of Al-doped ZnO nanoparticles. Besides, solid-state 27Al Magic Angle Spinning (MAS) NMR can provide information on the local environment of the aluminium ions inserted into the ZnO structure. The NMR results display that Al is occupying both octahedral and tetrahedral sites. Furthermore, at higher Al content the fraction of Al occupying tetrahedral sites decreases. The preliminary photocatalytic tests selecting Rhodamine B as target compound displayed that both undoped and Al-doped ZnO materials are active under UV-C, UV-A and visible-light irradiation, demonstrating their ability to remove the organic dye in water solution.