Surface photovoltage phase spectra for analysing the photogenerated charge transfer and photocatalytic activity of ZnFe2O4–TiO2nanotube arrays

Abstract

The transfer properties of the photogenerated charge carriers in TiO₂ nanotube arrays (TNAs) and ZnFe₂O₄ modified TiO₂ nanotube arrays (ZFO–TNAs) were investigated by surface photovoltage phase spectra. The modification of ZnFe₂O₄ on TNAs will lead to a new process of photogeneration of charge carriers. When irradiated with UV or visible light, before ZnFe₂O₄ modification photogenerated holes can transfer to the surface of TNAs; while after ZnFe₂O₄ modification, a process of photogenerated electrons transferring to the surface occurred. The different detected photogenerated charge transfer processes agree well with the photocatalytic reduction of Cr(VI) and the degradation of methyl orange experiments, which confirmed that the photogenerated holes transferring to the surface of the TNAs or ZFO–TNAs were beneficial for the reactions of photocatalytic reduction and electrons transferring to the surface were beneficial for photocatalytic degradation.