Combination of cobalt ferrite and graphene: High-performance and recyclable visible-light photocatalysis

[Display omitted] ► A magnetically separable CoFe2O4-graphene photocatalyst was successfully synthesized. ► The combination of CoFe2O4 nanoparticles with graphene results in a dramatic conversion of the inert CoFe2O4 into a highly active catalyst for the degradation of organic dyes. ► The significant enhancement in photoactivity under visible-light irradiation can be ascribed to reduction of graphene oxide. A straightforward strategy was designed for the fabrication of magnetically separable CoFe2O4-graphene photocatalysts with differing graphene content. It is very interesting that the combination of CoFe2O4 nanoparticles with graphene results in a dramatic conversion of the inert CoFe2O4 into a highly active catalyst for the degradation of methylene blue (MB), Rhodamine B (RhB), methyl orange (MO), active black BL-G and active red RGB under visible-light irradiation. The significant enhancement in photoactivity under visible-light irradiation can be ascribed to reduction of graphene oxide, because the photogenerated electrons of CoFe2O4 can transfer easily from the conduction band to the reduced graphene oxide, effectively preventing a direct recombination of electrons and holes. Hydroxyl radicals play the role of main oxidant in the CoFe2O4-graphene system and the radicals’ oxidation reaction is obviously dominant. CoFe2O4 nanoparticles themselves have a strong magnetic property, which can be used for magnetic separation in a suspension system, and therefore the introduction of additional magnetic supports is no longer necessary.