Combination of CoWO4 and Ag3VO4 with Fe3O4/ZnO nanocomposites: Magnetic photocatalysts with enhanced activity through p-n-n heterojunctions under visible light

Abstract

As novel visible-light-induced photocatalysts, a series of magnetically recyclable Fe3O4/ZnO/CoWO4/Ag3VO4 nanocomposites were fabricated through successive combination of Fe3O4/ZnO with CoWO4 and Ag3VO4. A facile refluxing-calcination procedure was employed to prepare these nanocomposites and they were characterized by various sophisticated instruments including XRD, EDX, SEM, TEM, UV–vis DRS, FT-IR, PL, as well as VSM and subsequently tested for photocatalytic degradations of three dyes and one colorless pollutants. The Fe3O4/ZnO/CoWO4/Ag3VO4 (20%) nanocomposite indicated excellent photodegradation for RhB under visible light, which is 78.4, 4.44, and 3.19 times superior to the Fe3O4/ZnO, Fe3O4/ZnO/Ag3VO4, and Fe3O4/ZnO/CoWO4 samples, respectively. Production of more electron-hole pairs due to presence of two small band gap semiconductors and retardation of the charge carriers from recombination due to formation of p-n-n heterojunctions are the main factors enhancing the photocatalytic performance. Additionally, the nanocomposite was readily recovered from the reaction solution using a magnet and its photocatalytic activity remained reasonable after some repetitive cycles.