阳极氧化制备TiO2纳米管及其光催化性能

采用电化学阳极氧化法在纯Ti表面制备出结构整齐有序的TiO₂纳米管阵列, 研究了不同溶液体系对TiO₂纳米管尺寸和形貌的影响. 利用X射线衍射仪和场发射扫描电镜表征所制备的TiO₂纳米管. 20 V反应15 h, 0.5 wt% HF＋1 mol/L (NH₄)H₂PO₄溶液中TiO₂纳米管直径为70～90 nm, 长度约2.2 μm, 在500 ℃的空气气氛下退火1 h, 纳米管薄膜以锐钛矿结构为主, 在该条件下所制备TiO₂纳米管的光电流密度达到3.2 mA/cm². 以该纳米管薄膜为光阳极, 施加0.45 V (vs. SCE)的外加偏压, 在125 W紫外光照射5 h后, 初始摩尔浓度为20×10^－6 mol/L的酸性红G (C₁₈H₁₃N₃Na₂₀₈S₂)在pH＝3时, 降解率达到92.4%.

Preparation of TiO2 Nanotubes by Anodization and Its Photocatalytic Performance

High density, well ordered, vertically aligned and uniform titanium oxide nano-tube arrays were fabricated on the surface of a pure titanium sheet by direct electrochemical anodic oxidation. The effect of different electrolytes on dimension and morphology has been studied. XRD and FE-SEM techniques have been used to characterize the titanium oxide nano-tube arrays. SEM shows that in an electrolyte of 0.5 wt% HF length of the nano-tubes did not increase after 20 mins. While in electrolyte of 0.5 wt% HF＋1 mol/L (NH₄)H₂PO₄, at 20 V anodizing voltage after 15 h, the average diameter of an nano-tubes was about 70～90 nm, and length of the nano-tubes was about 2.2 mm. XRD shows that after annealed for 1 h under 500 ℃ in air, the primary phase became anatase phase of TiO₂. Photo-electrochemical character curves have been measured in an electrolyte of 1 mol/L KOH under irradiation of a high-voltage mercury lamp, at photocurrent of about 3.2 mA/cm² for the nano-tubes of about 2.2 mm. Using the TiO₂ nano-tubes of about 2.2 μm in length as anode, under illumination of the high-voltage mercury lamp at 0.45 V (vs. SCE) bias potential, after 5 h, the degradation degree of an acid red G electrolyte was about 92.4%.