Enhanced photocatalytic capacity of ZnS–ZnO–Sm2O3 composites for the removal of dyes and antibiotics in visible light region

Abstract

ZnS–ZnO–Sm2O3 (Zn–Sm–XY) composites were prepared via the high-temperature calcination of core-shell structured ZnS@Sm2O3 for the enhanced photocatalytic degradation of dyes and antibiotics in visible light region. Effects of calcined temperature, Sm2O3 content, pH value, contaminant concentration, and inorganic ions on the photocatalytic activity were investigated. Ternary Zn–Sm composites exhibit the excellent photocatalytic activity for the visible light driven degradation of tetracycline hydrochloride. Among these composites, Zn–Sm–2B prepared via the heat-treatment of ZnS–Sm2O3 at 673K shows the best photocatalytic activity for the removal of tetracycline hydrochloride. The enhanced photocatalytic activity of Zn–Sm–2B is also achieved for the visible light driven degradation of methyl orange, methylene blue, and rhodamine B within 20min. In addition, Zn–Sm–6C calcined from Zn–Sm–C at 1073K as well as Zn–Sm–2B exhibits excellent photocatalytic activity. OH and O2− radicals are vital for the enhanced photocatalytic activity of Zn–Sm–2B and Zn–Sm–2B in visible light region, respectively. The lattice defects, sulfur vacancies, and oxygen vacancies facilitate the efficient charge transfer and the rapid separation of electron-hole pairs at the junction interface of Zn–Sm–2B.