Influence of doping with Sm3+ on photocatalytic reuse of ZnO thin films obtained by spin coating

Abstract

The difficulty in the powder reuse favors the study of materials in the form of thin films. ZnO based films have high photocatalytic potential. In this work, ZnO:xSm3+ (x = 0, 1, 2 and 4 %mol) thin films were prepared by spin coating method. The resins obtained to manufacture the thin films were prepared by complex polymerization method. The samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and spectroscopy UV-Vis. XRD patterns indicate that doping with 4%Sm forms Sm2O3 as the secondary phase. FE-SEM images of the cross section of thin films indicated a uniform thickness ranging from 354 to 367 nm between samples. The incorporation of Sm3+ ions in the ZnO lattice increases the Egap of the films. The photocatalytic performance of the films was tested with the photodegradation of methylene blue dye. Pure ZnO and ZnO:1%Sm3+ exhibited the best activity in the photodegradation. Thin films of pure ZnO exhibit the best photocatalytic results for the first cycle, but considerably reduce their efficiency with reuse. Sm3+ incorporation, without secondary phase formation, was efficient for the maintenance of the photocatalytic property after 3 cycles.