Preparation of ZnFe2O4/TiO2 nanotube array electrode and photoelectrocatalysis degradation of phenol

Abstract

A well-aligned ZnFe2O4/TiO2 nanotube array electrode with visible-light activity was successfully prepared using a two-step electrochemical process of anodization and a novel cathodic electrodeposition method. Its morphology and chemical composition was characterized by environmental scanning electron microscope, transmission electron microscope and X-ray diffraction. The ZnFe2O4 nanoparticles were highly dispersed inside the TiO2 nanotube but minimized at the tube entrances. The composites displayed a strong photo response in the visible region and low recombination rate of the electronhole pairs. The synthesized ZnFe2O4/TiO2 nanotube electrode showed much higher photocurrent density in the visible region than pure TiO2 nanotube electrode. In addition, we discussed the influence on the electrode properties of ZnFe2O4/TiO2 nanotube array from mass concentration sedimentary time, cycle times and sedimentary voltage. The optimal experimental condition was 0.05 mol/L Zn (NO3)3+0.1 mol/L Fe (NO3)3, 20 min 5 times and 1 V. The photocatalytic activity of the composite electrode was evaluated in the decomposition of phenol under visible light irradiation. It was found that the degradation rate increased with voltages and an increase in the activity by a factor of 1.5~2 relative to pure TiO2 nanotube was obtained under the optimal conditions. The improved photoelectrocatalytic activity is derived from the synergetic effect between ZnFe2O4 and TiO2, which promoted the migration efficiency of photogenerated carriers at the interface of the composite and enhanced the efficiency of photon harvesting. Under the visible region, the ZnFe2O4/TiO2 nanotube electrode was operated under the same experimental conditions. The results clearly show a good recycle with the degradation rate of 95% even after five repeated experiments. These results demonstrate that the ZnFe2O4/TiO2 nanotube electrode was an efficient material in utilizing solar energy for the photodecomposition of pollutants. © 2013 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.