Effect of Heat-treatment Process on the Structure and Photoelectric Performance of TiO_2 Nanotube Arrays

TiO2 nanotube arrays were made on the titanium foil by the method of anodic oxidation,and then crystallized by different heat-treatment processes.The morphology and structure of the TiO2 nanotube arrays were characterized by SEM and XRD.The results showed that the TiO2 nanotube arrays prepared by anodic oxidation and annealed at the temperature range of 450 750℃ were nanocrystalline structure,and the average measurement of the crystal particle grew with the increasing of the annealing temperature.The average crystal size of TiO2 nanotube arrays annealed in the nitrogen atmosphere is smaller than that annealed in the air atmosphere at the same temperature.Annealing in the nitrogen atmosphere can widen the limit of the transformation temperature from Anatase to Rutile.Annealed above 650℃,the TiO2 nanotube arrays can be doped into a small amount of nitrogen.The results of light open-circuit potential tests and the steady-state polarization curves tests show that the TiO2 namotube arrays electrode has the best photoelectric response properties after being annealed in the nitrogen atmosphere at 650℃ for 2 h.The arrays have mixed crystal structure of Anatase and Rutile.