Green-route synthesis and ab-initio studies of a highly efficient nano photocatalyst:Ce/zinc-oxide nanopetals

In the present work, Zinc-oxide nanostructures and Ce/Zinc-oxide nanopetals were synthesized by a new environmentally friendly green synthesis method using the Withania coagulans plant. Cerium nitrate Ce(NO₃)₃ and zinc nitrate Zn(NO₃)₂ were used as precursors. The prepared nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet spectroscopy (UV-vis). Crystal planes (100), (002), (101), (102), (110), (103), (200), (112) and (201) at 2θ 31.75°, 34.35°, 36.2°, 47.55°, 56.6°, 62.75°, 66.3°, 67.9°, and 69.09° respectively confirmed the hexagonal wurtzite crystal structure of Zinc-oxide. Angular shifts for Ce_1% doped Zinc-oxide and Ce_3% doped Zinc-oxide nanopetal nanostructures were observed in the (100) and (101) planes of the crystal. More specifically, using Scherrer's equation, the crystallite sizes of Zinc-oxide, Ce_1% doped Zinc-oxide nanopetals, Ce_3% doped Zinc-oxide nanopetals, and Ce_5% doped Zinc-oxide nanopetals were 16.48 ± 02 nm, 17.8 ± 2 nm, 18.8 ± 2 nm, and 18.87 ± 2 nm, respectively. The pure Zinc-oxide grain had the appearance of a nanoflower. On the other hand, the nanopetal structure of Ce_5% doped Zinc-oxide nanopetals had oval-shaped nanopetal morphology. The absorption peaks were observed at 373, 376.4, 377, and 378 nm for Zinc-oxide, Ce_1% doped Zinc-oxide nanopetals, Ce_3% doped Zinc-oxide nanopetals, and Ce_5% doped Zinc-oxide nanopetals, respectively, which results in a progressive redshift. The gap energies of Zinc-oxide, Ce_1% doped Zinc-oxide nanopetals, Ce_3% doped Zinc-oxide nanopetals, and Ce_5% doped Zinc-oxide nanopetals were 2.796, 2.645, 2.534, and 2.448 eV, respectively. Photodegradation under visible light (>400 nm) indicates the high efficiency of the photocatalyst based on Ce_5% doped Zinc-oxide nanopetals. DFT calculations, structural changes, charge analysis, and electronic band structures were carried out to confirm the experiment.