Photocatalytic and Photoluminescence Studies of La, Ce, and Dy Co-doped ZnO Nanoflowers

In the present work, ZnO nanoparticles were doped with varying concentration of lanthanum (La), cerium (Ce), and dysprosium (Dy) using a simple and cost-effective co-precipitation approach at low temperatures. The resulting powders were calcined at 500 °C for 1 h using a muffle furnace, to produce La, Ce, and Dy-co-doped ZnO nanoparticles with varying stoichiometry, viz. (Zn 0.97 La 0.01 Ce 0 .01 Dy 0.01 O, Zn 0.94 La 0.02 Ce 0.02 Dy 0.02 O, Zn 0.91 La 0.03 Ce 0.03 Dy 0.03 O, Zn 0.88 La 0.04 Ce 0.04 Dy 0.04 O, and Zn 0.85 La 0.05 Ce 0.05 Dy 0.05 O). This is a simple approach for doping and does not require a complex equipment, harmful chemical, or sophisticated machinery. The synthesized powders were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) for studying the structure, purity, and grain morphology. Compositional study was done using EDS (SEM/EDS Hitachi 3600 N). The average crystallite size was calculated using XRD and was found to be 35 nm, and it also indicated a hexagonal wurtizite structure with no secondary peaks. A change in morphology from nanorods to nanoflowers was observed as the concentration of dopants increased. Photoluminescence (PL) spectra indicated a redshift in the absorption edge toward the visible region of solar spectrum and this was further confirmed by diffuse reflectance spectra (DRS). The photocatalytic properties of undoped and La, Ce, and Dy-co-doped ZnO nanoparticles were observed by examining the photodegradation of Rhodamine B dye under UV irradiation. The elimination of dye color indicated the total degradation of organic molecule. The results revealed that ZnO photocatalyst with La, Ce, and Dy co-dopant concentration Zn 0.85 La 0.05 Ce 0.05 Dy 0.05 O exhibited the best photocatalytic performance (95%) as compared to undoped ZnO. The improved photocatalytic performance can be attributed to the increased surface oxygen vacancies and adsorption capacity. The delay in recombination of charge carriers due to creation trap states in the bandgap of ZnO further improves the photocatalytic performance of doped samples.