Synthesis of Co₃O₄/graphene composite catalysts through CTAB-assisted method for Orange II degradation by activation of peroxymonosulfate

Co₃O₄/graphene composites were synthesized and their high catalytic activity for the activation of peroxymonosulfate to remove the azo dye (Orange II) in aqueous solutions was found. As for the poor quality of rGO by the chemical process of graphene oxide, here, pristine graphite was exfoliated into graphene flakes through direct sonication with assistance of cetyltrimethyl ammonium bromide, which serves as a dispersant in the solvothermal procedure. The physical and chemical performance of Co₃O₄/graphene was characterised by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy and thermogravimetric analysis. The obtained Co₃O₄ nanocrystals were 15–25 nm in size and connected with each other to form the shape of sticks dispersing on graphene sheets. The Co₃O₄/graphene composites completely degraded Orange II solutions within 10 min, the catalyst can be reutilized, and the catalytic activity of the Co₃O₄/graphene dropped slightly after four successive runs. In addition, the mechanism for the formation of Co₃O₄/graphene nanostructures is also illustrated.