阳极氧化制备TiO2纳米管及其光催化性能

Preparation of TiO_2 Nanotubes by Anodization and Its Photocatalytic Performance

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.20V反应15h,0.5wt%HF+1mol/L(NH4)H2PO4溶液中TiO2纳米管直径为70～90nm,长度约2.2μm,在500℃的空气气氛下退火1h,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3.2mA/cm2.以该纳米管薄膜为光阳极,施加0.45V(vs.SCE)的外加偏压,在125W紫外光照射5h后,初始摩尔浓度为20×10-6mol/L的酸性红G(C18H13N3Na208S2)在pH=3时,降解率达到92.4%.

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 μm. 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/cm^2 for the nano-tubes of about 2.2 μm. 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%.