In this study, TiO 2 nanotube (TNT) arrays were grown on Ti metal using the anodic oxidation method. After finding the parameters to grow TNT arrays with maximum specific surface area, the TNT arrays were annealed over a temperature range of 350-600 ℃. From the X-ray diffraction (XRD) patterns we found that the as-deposited TNT arrays revealed an amorphous phase. As the annealing temperature was increased from 350 to 500 ℃, the diffraction intensity of the anatase phase increased. As the annealing temperature reached 600 ℃, both the anatase phase and the rutile phase were observed in the arrays. The TNT arrays with different annealing temperatures were used to carry out experiments in moss decomposition and methylene blue degradation. The surface observation was used to judge the effect on moss decomposition, and the Beer-Lambert law was used to judge the effect on methylene blue degradation. We show that TNT arrays annealed at 500 ℃ functioned best in both moss decomposition and methylene blue degradation because of the presence of only the anatase phase.

In this study, we analyzed the growth and annealing parameters of TiO 2 nanotube (TNT) arrays and their effect on C 14 H 14 N 3 NaO 3 S methyl orange degradation. At first, the TNT arrays were grown on Ti metal by the anodic oxidation method under DC voltages of 10-30 V. Surface observation was used to judge the effect of the grown TNT arrays, and we found that 20 V was the optimum voltage in this study. After the TNT arrays were grown under the DC bias of 20 V, the TNT arrays were annealed at temperatures in the range of 400-500 ℃ for time durations of 1-3 h. From the X-ray diffraction (XRD) patterns, we found that the as-grown TNT arrays have an amorphous phase. Because different annealing temperatures and annealing times were used, the XRD patterns showed that only the anatase TiO 2 phase and Ti phase were observed. The TNT arrays with different annealing parameters were used to carry out experiments on C 14 H 14 N 3 NaO 3 S methyl orange degradation. The transmittance spectra of C 14 H 14 N 3 NaO 3 S methyl orange has one strong and wide absorption band located at 463-464 nm and a small absorption band located at 270-271 nm. The C 14 H 14 N 3 NaO 3 S methyl orange solutions under only UV-light irradiation were almost unchanged with the increase in irradiation time. After the annealed TNT arrays were used to degrade the C 14 H 14 N 3 NaO 3 S methyl orange, we found that the TNT arrays grown at 20 V and annealed for 1 h at 450 ℃ had the best effect on the C 14 H 14 N 3 NaO 3 S methyl orange degradation.