Magnetically Separable ZnFe2O4–Graphene Catalyst and its High Photocatalytic Performance under Visible Light Irradiation

A magnetically separable ZnFe 2 O 4 –graphene nanocomposite photocatalyst with different graphene content was prepared by a facile one-step hydrothermal method. The graphene sheets in this nanocomposite photocatalyst are exfoliated and decorated with ZnFe 2 O 4 nanocrystals. It was found that in the presence of H 2 O 2, the photodegradation rate of methylene blue (MB) was 88% after visible light irradiation for only 5 min and reached up to 99% after irradiation for 90 min. In comparison with pure ZnFe 2 O 4 catalyst, ZnFe 2 O 4 –graphene serves a dual function as the catalyst for photoelectrochemical degradation of MB and the generator of a strong oxidant hydroxyl radical (·OH) via photoelectrochemical decomposition of H 2 O 2 under visible light irradiation. ZnFe 2 O 4 nanoparticles themselves have a magnetic property, which makes the ZnFe 2 O 4 –graphene composite magnetically separable in a suspension system, and therefore it does not require additional magnetic components as is the usual case.