▎ 摘　　要

The photocatalytic degradation of methylene blue dye (MB) has been investigated using bare manganese ferrite (MnFe2O4) nanoparticles and MnFe2O4 nanoparticles-decorated reduced graphene oxide heterostructures (MnFe2O4/rGO) under ultra-violet irradiation. The MnFe2O4 nanoparticles prepared using a facile co-precipitation method showed single-phase cubic spinel structure and superparamagnetic property. The MnFe2O4/rGO heterostructures showed the formation of sphere-like MnFe2O4 nanoparticles well-attached on rGO nanosheets with reduced agglomeration. The photocatalysis study shows that MnFe2O4/rGO had higher photocatalytic activity compared to bare MnFe2O4 nanoparticles. MB degraded by 84% in presence of MnFe2O4 after UV irradiation of 290 min, while 97% of it degraded in merely 60 min in case of MnFe2O4/rGO heterostructures. This is further confirmed by the well-fitted Langmuir-Hinshelwood Kinetics equation. This improvement in the photocatalytic activity of the heterostructure is attributed mainly to the retardation of the recombination process of photo-generated charge carriers. Hydroxyl radicals play the crucial role in the MnFe2O4-graphene system for MB photodegradation. Thus, MnFe2O4 nanoparticles-decorated reduced graphene oxide heterostructures can act as potential photocatalyst for degradation of hazardous organic dyes present in water.