Reduced graphene oxide-spinel ferrite nano-hybrids as magnetically separable and recyclable visible light driven photocatalyst

High quality magnetically separable Ni0.65Zn0.35Fe2O4 nanoparticles were synthesized by surfactant assisted co-precipitation method. Spinel structure of these ferrite nanoparticles was confirmed by X-ray diffraction (XRD). Reduced graphene oxide (rGO) was prepared by wet chemical approach and then utilized to make the composites with ferrite nanoparticles. The successful homogenous distribution of ferrites nanoparticles onto the graphene sheets was observed by scanning electron microscopic (SEM) analysis. The ferrite@rGO composite exhibited the strong absorption in visible region as observed by UV-vis measurements. Optical band gap studies confirmed that the prepared spinel ferrite Ni0.65Zn0.35Fe2O4 nanoparticles can be utilized for visible light driven photocatalytic activity studies. The optical (direct) band gap for Ni0.65Zn0.35Fe2O4 nanoparticles as calculated by Tauc plot was found 1.91 eV. This bandgap lies in the visible region i.e. < 3.0 eV. The band gap of ferrite nanoparticles was reduced to 1.84 eV when they were mixed with rGO to prepare the nano-hybrids. The photocatalytic activity of the ferrite nanoparticles was analyzed by photochemical decomposition of methylene blue (MB) under visible light irradiation. Photocatalytic activity of Ni0.65Zn0.33Fe2O4@rGO nano-hybrids was found better as compared to bare nanoparticles. Improved photodegradation of MB by NiZnFe2O4/rGO was ascribed due to effective separation of photo-generated electron-hole pairs. The ferrite nanoparticles exhibit ferromagnetic nature; therefore they can be recovered easily by conventional magnets. Thus these ferrite nanoparticles and their nano-hybrids with rGO can be recycled and reused easily.