Synthesis of novel Zn0.5Mg0.5Fe2O4@TiO2 nanotube arrays with enhanced photoelectrocatalytic properties

Abstract

A novel nanocomposite electrode with tight and vertically aligned Zn_0.5Mg_0.5Fe₂O₄@TiO₂ nanotube arrays (NTs) has been successfully synthesized via an ultrasonically assisted electrodeposition strategy. The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) of the composite nanostructures indicated that the as-prepared electrodes were well-aligned TiO₂ NTs with Zn_0.5Mg_0.5Fe₂O₄ nanoparticles. The enhanced absorption of the nanocomposite electrode under simulated sun light and visible light regions were observed. The photoelectrochemical performance of the Zn_0.5Mg_0.5Fe₂O₄@TiO₂ nanotube arrays showed excellent sensitive response to visible light. The surface-interface charge separation and transfer of photo-induced electrons and holes were also demonstrated by optical characterization. Meanwhile, the photoelectrochemical investigations clearly illustrated that the Zn_0.5Mg_0.5Fe₂O₄@TiO₂ composite NTs had more effective photo-conversion capability than the unloaded TiO₂ NTs. The saturated photocurrent density of the doped electrode was about 6.5 fold and 4 fold as high as that of the TiO₂ NTs under the illumination of visible light and simulated sun light, respectively. In addition, the enhanced photoelectrocatalytic (PEC) ability of the as-prepared electrode was demonstrated in the degradation of toxic p-nitrophenol species. The much improved PEC activity can be attributed to both the visible-light photocatalytic activity of Zn_0.5Mg_0.5Fe₂O₄ and the heterostructure between Zn_0.5Mg_0.5Fe₂O₄ and TiO₂.