Ternary TiO 2 /Fe 3 O 4 /CoWO 4 nanocomposites: Novel magnetic visible-light-driven photocatalysts with substantially enhanced activity through p-n heterojunction.

Herein, novel magnetic TiO2 /Fe3 O4 /CoWO4 nanocomposites were fabricated using a simple refluxing method followed by a calcination step at 450 °C. Photocatalytic activity of these nanocomposites were studied by decomposing rhodamine B, methyl orange, and fuchsine dye contaminants under visible-light illumination. Among the fabricated photocatalysts, the TiO2 /Fe3 O4 /CoWO4 (30%) photocatalyst exhibited superior activity. The degradation rate constant for rhodamine B by this ternary nanocomposite was 8.5 and 5.6 folds greater than those of the pure TiO2 and TiO2 /Fe3 O4 photocatalysts, respectively. Trapping experiments showed that superoxide anion radicals played critical role during the photocatalytic process. Visible-light harvesting due to the presence of CoWO4 and effective suppression of the charge carriers from recombination due to formation of p-n heterojunction are the major parameters affecting the photocatalytic activity. Furthermore, the TiO2 /Fe3 O4 /CoWO4 (30%) photocatalyst displayed highly stable recycling performances. The present study provides a new strategy to design and fabricate magnetically recoverable photocatalysts based on TiO2 with considerable activity under visible-light.