Synthesis, characterization, and evaluation of the photocatalytic properties of zinc oxide co-doped with lanthanides elements

Abstract

Zinc oxide nanoparticles (NPs) co-doped with various concentrations of lanthanides cerium and ytterbium (Zn1-2xCexYbxO, x = 0.0, 0.01, 0.03, and 0.05) were synthesized via the sol-gel auto-combustion method. All prepared samples including CYZO0 (x = 0.0), CYZO1 (x = 0.01) CYZO3 (x = 0.03), and CYZO5 (x = 0.05) were subsequently characterized. The effects of the concentration of Ce and Yb on the structural, optical, and photocatalytic properties of ZnO NPs were deeply explored. The structural analysis showed that the as-synthesized samples were matched with a hexagonal structure. The co-doping altered the crystal structure of the material. The lattice constants increased with increasing the concentration of Ce and Yb ions. The crystallite size was reduced from 53.24 ± 0.05 nm CYZO0 to 52.28 ± 0.05 nm, 34.90 ± 0.05 nm, and 36.85 ± 0.05 nm for CYZO1, CYZO3, CYZO5, respectively. UV–Vis analysis showed a variation in the bandgap energy values with Yb and Ce co-doping. The photocatalytic activities of Yb and Ce co-doped ZnO were assessed by taking methyl orange (MO) as an organic dye. The absorption peaks at 464 nm for MO dye reduced progressively with prolonged exposure time indicating the presence of the photocatalytic degradation reaction of MO. The constant rate k was found to be 0.027 min−1 for CYZO0, and 0.024 min−1 for CYZO1, and then sharply decreased to 0.0064 min−1, and 0.0065 min−1 for CYZO3 and CYZO5, respectively. It is suggested that the photocatalytic efficiency is intensely dependent on the synergistic effect of both Yb and Ce co-doping.