Influence of La-doping on phase transformation and photocatalytic properties of ZnTiO₃ nanoparticles synthesized via modified sol-gel method

Non-doped and La-doped ZnTiO₃ nanoparticles were successfully synthesized via a modified sol–gel method. The synthesized nanoparticles were structurally characterized by PXRD, UV-vis DRS, FT-IR, SEM-EDS, TEM, Raman and photoluminescence spectroscopy. The results show that doping of La into the framework of ZnTiO₃ has a strong influence on the physico-chemical properties of the synthesized nanoparticles. XRD results clearly show that the non-doped ZnTiO₃ exhibits a hexagonal phase at 800 °C, whereas the La-doped ZnTiO₃ exhibits a cubic phase under similar experimental conditions. In spite of the fact that it has a large ionic radius, the La is efficiently involved in the evolution process by blocking the crystal growth and the cubic to hexagonal transformation in ZnTiO₃. Interestingly the absorption edge of the La-doped ZnTiO₃ nanoparticles shifted from the UV region to the visible region. The photocatalytic activity of the La-doped ZnTiO₃ nanoparticles was evaluated for the degradation of Rhodamine B under sunlight irradiation. The optimum photocatalytic activity was obtained for 2 atom% La-doped ZnTiO₃, which is much higher than that of the non-doped ZnTiO₃ as well as commercial N-TiO₂. A possible mechanism for the degradation of Rhodamine B over La-doped ZnTiO₃ was also discussed by trapping experiments. More importantly, the reusability of these nanoparticles is high. Hence La-doped ZnTiO₃ nanoparticles can be used as efficient photocatalysts for environmental applications.