Sol–gel synthesis and photocatalytic activity of ZnO–Ag–Sm nanoparticles for water treatment

Abstract

ZnO–Ag–Sm nanoparticles with excellent photocatalytic performance were synthesized through a simple sol–gel method. The samples were characterized by X-ray diffraction (XRD), ultraviolet–visible spectroscopy (UV–Vis), transmission electron microscopy (TEM), photoluminescence spectroscopy (PL), Brunauer–Emmett–Teller surface area measurement (BET) and energy dispersive X-ray spectroscopy (EDS). The presence of Ag nanoparticles and samarium doping acted as trapping centers and promoted the separation of photogenerated electron–hole pairs and thus enhanced the photocatalytic activity. Ag nanoparticles with a diameter of ~ 4 nm were decorated on the surface of ZnO. The results indicated that ZnO–Ag–Sm exhibited much faster rate in photodegradation of methylene blue (MB) than ZnO and ZnO–Ag. Ag addition and Sm doping leaded to a red-shift in the absorption band and increased visible light absorption. Finally, a mechanism was proposed for the photocatalytic activity of ZnO–Ag–Sm nanoparticles.