New Magnetically Recyclable Reduced Graphene Oxide rGO/MFe 2 O 4 (M= Ca, Mg)/Ag 3 PO 4 Nanocomposites With Remarkably Enhanced Visible-light Photocatalytic Activity and Stability.

New magnetically separable CaFe2 O4 /Ag3 PO4 , MgFe2 O4 /Ag3 PO4 , rGO/CaFe2 O4 /Ag3 PO4 and rGO/MgFe2 O4 /Ag3 PO4 photocatalysts were synthesized by the hydrothermal and ion-exchange deposition method. These four types of photocatalyst were used for degradation of Methylene blue (MB), Methyl orange (MO) and 4-chlorophenol (4-CP) in aqueous solution under visible-light illumination. The optimized photocatalyst, i.e. rGO/CaFe2 O4 /Ag3 PO4 with a mass ratio of (1:3:9) composite not only shows the highest photocatalytic performance for the degradation of MB, MO and 4-CP under visible light irradiation among the other synthesized photocatalysts but also exhibits high reusability and stability for at least five cycles. It was found that the impressive separation of electron-hole pairs as well as presence of rGO sheets which act as a high speed charge transfer were responsible for increasing photocatalytic activity over the optimized photocatalyst under visible-light irradiation. A possible mechanism for the increased photocatalytic activity of the rGO/CaFe2 O4 /Ag3 PO4 with a mass ratio of (1:3:9) composite was discussed in detail.