Enhanced photovoltaic effect of TiO2-based composite ZnFe2O4/TiO2

► The TiO2 (Degussa P25)-based ZnFe2O4/TiO2 composite with enhanced photovoltaic effect compared with pure TiO2 (Degussa P25) was prepared. ► The mechanisms of the enhancement were investigated. ► The photovoltaic effect enhancement is mainly due to the decrease of the trap density of the composite and the energy level matching between TiO2 (Degussa P25) and ZnFe2O4. ► These result in the increase of photogenerated carrier concentration, improvement of the separation efficiency of photogenerated carriers. A TiO2-based composite, ZnFe2O4/TiO2, was prepared with a commercial TiO2 (Degussa P25) and ZnFe2O4 nanopowders using a simple method. The composite was characterized by X-ray diffraction (XRD), UV–vis absorption spectrum, surface photovoltage spectroscopy (SPS) and SEM. The composite presents an enhanced photovoltaic effect compared with the pure TiO2. The trap distributions of TiO2 and ZnFe2O4/TiO2 composite were investigated and the energy levels of TiO2 and ZnFe2O4 were analyzed. The results indicate that the enhancement of photovoltaic effect is mainly due to the increase of photo-generated carrier concentration and improvement of the separation efficiency of photo-generated carriers by the addition of ZnFe2O4.