Enhanced photoelectrochemical and photocatalytic behaviors of MFe ₂O ₄ (M = Ni, Co, Zn and Sr) modified TiO ₂ nanorod arrays

Abstract

Modified TiO ₂ nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe ₂O ₄, M = Ni, Co, Zn, and Sr), are utilized to modify the well aligned TiO ₂ nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe ₂O ₄/TiO ₂ NRAs show obvious red shift into the visible light region compared with the TiO ₂ NRAs. In particular, NiFe ₂O ₄ modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO ₂ NRAs. Furthermore, the separation and transfer of charge carriers after MFe ₂O ₄ modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe ₂O ₄/TiO ₂ NRAs is proposed. Through comparison among different transition metals modified TiO ₂ with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO ₂ nanomaterials as visible light active photocatalysts.