Highly photocatalytic activities of magnetically separable reduced graphene oxide-CoFe2O4 hybrid nanostructures in dye photodegradation

The CoFe2O4 nanoparticles and reduced graphene oxide-CoFe2O4 (rGO-CoFe2O4) hybrid nanostructures with rGO/CoFe2O4 ratio of 0.05, and 0.1 were hydrothermally synthesized. The microstrutrual and photocatalytic activities of nanoparticles and hybrids were studied in the photodegradation of malachite green in the water. The CoFe2O4 nanoparticles and them in the hybrids showed uniform granular morphology with average particle sizes of similar to 17 nm. Because higher valence band energy of the CoFe2O4, the photogenerated electrons can be transformed from the CoFe2O4 to the rGO. Therefore, the hybrids showed obviously greater sunlight-excited photocatalytic and Fenton-like photocatalytic activities to the dye degradation, increased as increasing rGO/CoFe2O4 ratio, than the nanoparticles and increased as increasing rGO/CoFe2O4 ratio. Moreover, the photodegradation rate is larger at higher initial solution pH = 7 than at pH = 5, whereas the photo-Fenton-like reaction is intenser at higher H2O2 concentration. The quasi-kinetic rate constants of the photocatalysis systems are in the range of similar to 0.43-0.85 h(-1) and remarkably increase to similar to 9.21-18.42 h(-1) by synthetically using H2O2. The nanoparticles and hybrids also showed strong ferromagnetic property with the saturation magnetization of similar to 61.82-63.73 emu/g, which provides a well magnetic separation performance of the nanoparticles and hybrids from the degraded solution. (C) 2016 Elsevier B.V. All rights reserved.