Engineering the photocatalytic efficiency of nanoscale TiO2 anatase with doped (Nd/Y) and co-doped (Nd–Y/Nd–Sm) lanthanides to decompose the azo dye orange G under UV-VIS irradiation

Abstract

Engineering a powerful visible light-driven organic dye decomposition has been always considered a crucial challenge in the photocatalytic domain. Therefore, the high photocatalytic efficiency of Nd single doped and Nd/Y, Nd/Sm co-doped TiO₂ anatase nanoparticles was verified under UV-vis light using the Azo dye orange G. The nanomaterials were successfully synthetized using a sol–gel method. X-Ray diffraction (XRD), Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and UV-vis spectroscopy (UV-VIS) were used to characterize the obtained nanopowders. First-principles calculations were conducted on undoped and doped/co-doped anatase TiO₂ to obtain insight into the effect of doping the structure with rare earth elements on its optical properties. The relative variations in the lattice volumes of the doped systems agreed with the experiment. The calculated magnetic moments indicated a valence of +3 for all doping elements. Doping and co-doping TiO₂ with Nd, Y and Sm elements were found to be energetically favorable. The calculated electronic structure revealed that doping TiO₂ with Nd allows the material to absorb radiation in the visible range by creating Nd-4f impurity states, which highly improves the photocatalytic efficiency. The photocatalytic efficiency evaluation of pure TiO₂, Ti_0.99Nd_0.01O₂, Ti_0.99Nd_0.005Y_0.005O₂ and Ti_0.99Nd_0.005Y_0.005O₂ anatase nanoparticles has been studied using the Azo dye orange G under a wavelength range of 300–800 nm. The Nd/Y–TiO₂ anatase nanopowders displayed the highest degradation of 96.34% in 105 minutes only. The stability and reusability of the photocatalysts were studied, and all the samples showed high photocatalytic stability, easy recovery and reusability. Nd/Y–TiO₂ anatase showed the best stability. These results demonstrate that the experimental conditions, the chosen concentration and the type of dopants play a major role in maintaining and improving the anatase structure to elaborate innovative nanoparticles with particular physico-chemical properties in order to obtain great photocatalytic activity.