Synthesis and Visible Light Photocatalytic Activity of Spinel MAl2O4 (M=Mg, Zn, Cu)

Aluminium spinel MAl2O4 (M = Mg, Zn, Cu) photocatalysts were prepared by a sol-gel method. The prepared samples were characterized by X-ray diffraction and transmission electron microscope. The results indicated that the samples possess a single spinel-type structure. Ultraviolet-visible diffuse reflectance spectra showed an extension of light absorption into the visible region. The spinel MAl2O4 photocatalysts exhibited high photocatalytic activity for the degradation of industrial dyes under high pressure mercury lamp and visible light irradiation, especially CuAl2O4. With the decrease of band gap of MAl2O4 (M = Mg, Zn, Cu), the photocatalytic activity increases. The possible reasons are discussed from the crystal field theory and energy band theory. These characteristics make the aluminium spinel MAl2O4 (M = Mg, Zn, Cu) photocatalysts to be promising candidates for the photocatalytic degradation of dyes.