Hierarchical flower-like Co3−xFexO4 ferrite hollow spheres: facile synthesis and catalysis in the degradation of methylene blue

Abstract

A facile method is proposed for the synthesis of three-dimensional (3D) flower-like Co_3−xFe_xO₄ ferrite (CF) hollow spheres, using SiO₂@FeOOH as precursor. The CF hollow spheres are efficient for the catalytic degradation of methylene blue (MB) in the presence of H₂O₂ at 80 °C. The obtained CF hollow spheres were characterized using transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, X-ray photo-electron spectroscopy, and N₂ adsorption–desorption isotherm measurements. The formation of 3D hierarchical flower-like superstructure was influenced by the relative amount of urea used. As the mole ratio of CoCl₂ and urea decreased, the structure of the products was tailored from yolk-like spheres to hollow spheres with different sized void interiors. Moreover, N₂ adsorption–desorption isotherm analysis showed that the CF hollow spheres have a large specific surface area (163 m² g⁻¹) which provided more activity sites. The CF hollow spheres can catalyze the oxidation of MB efficiently. These results indicate that the designed CF hollow spheres exhibit promising capability for the degradation of dyes.