| Photocatalytic strategy is considered to be an effective method which has been widely used in environmental pollution control due to its spontaneous utilizing sunlight, photogenerated radicals with strong oxidation ability, mild reaction conditions and no secondary pollution. TiO2 nanotube arrays have received numerous investigations in the field of photocatalysis for their simple fabrication, good charge transfer performance, low cost and recyclable properties. However, TiO2 nanotube arrays have been restricted in further application of water pollutant control by two obstacles, which are utilizing ultraviolet light and high recombination of photogenerated electron-hole pairs. Hence, increasing researches focus on new and efficient semiconductors with narrow-band gap to modify TiO2 nanotube arrays. Spinel ferrites are recommended as excellent candidates because of their famous ferromagnetic properties and suitable band gap position. By utilizing the intrinsic ferromagnetic field combining with heteroj unction channel, it will achieve the photogenerated electron-hole pairs separation, resulting in the obvious enhancement of photocatalytic performance of the composite catalysts. Thus, spinel ferrites have been employed to decorate TiO2 nanotube arrays in this work. Photochemical properties and photocatalytic performance of the composite material have been characterized. The main searching contents are as following:In the first part, CuFe2O4/TiO2 composite electrode was synthesized via an ultrasound-assisted electrodeposition method combining an anodic oxidation. CuFe2O4 nanoparticles were uniformly deposited on the tube entrance by physical and chemical characterizations. It is demonstrated that photoelectrochemical properties of the composite electrode have been obviously improved, which the photoconversion efficiencies of the loaded electrode gained 27 folds and 1.6 folds enhancement under visible light and simulated sun light irradiation, respectively.In the second part, the ultrasound-assisted electrodeposition strategy was also employed to construct Zno.5Mg0.5Fe2O4TiO2 electrode. The doped particles could be found uniform on the surface of nanotube, some of particles were deposited into the inner wall. Optical characterization demonstrated that the loading of Zn0.5Mg0.5Fe2O4 particles effectively broadened the spectrum response range of the composite electrode and inhibited the photogenerated charge recombination. Photoconversion efficiencies of as-prepared composite catalysts have received 2.54 folds and 1.8 folds as high as pure TiO2 with the illumination of visible light and simulated sun light. This study was compared the photocatalytic degredation of p-nitrophenol over Zn0.5Mg0.5Fe2O4/TiO2 and TiO2 electrode, the degradation efficiency of the one after deposited procedure got 2.8 times and 2.03 times higher than that before under visible light and simulated sun light irradiation, respectively. The testing result of EPR confirmed that·OH and·OH2- have engaged in PNP degradation processes.At last, Mn0.5Zn0.5Fe204/Ti02 nanocomposite electrode was prepared by a simple ultrasound-assisted impregnation technique. Mn0.5Zn0.5Fe2O4 loading gave rise to 2.35 folds and 2.3 folds improvement for photocurrent density and photoconversion efficiency of TiO2 nanotube arrays under simulated sun light irradiation, respectively. The degradation efficiency of 2,4-dichlorophenol (2,4-DCP) over the composite electrode achieved 3 times as high as pure TiO2 electrode under. Oxygen species involved in photocatalytic decompose of 2,4-DCP were investigated combining fluorescent probe technique with EPR strategy. The main species were detected as photogenerated holes. Finally, preliminary degradation mechanism of 2,4-DCP over Mn0.5Zn0.5Fe204/TiO2 electrode was suggested by analyzing degradation intermediates in different degradation time using LC-MS technique. |
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