Ti^(3+)掺杂的TiO_2纳米管阵列制备及其电化学阻抗谱研究

Preparation of Ti^(3+)-doped TiO_2 nanotube array and its electrochemical impedance spectroscopic study

在质量分数为1.0%的HF溶液中,对纯钛片进行阳极氧化,获得了TiO2纳米管(TNTs)阵列。采用扫描电镜和X射线衍射表征了TNTs阵列的表面形貌及晶型结构。在450°C下热处理可以使TNTs由无定形态转化为锐钛矿型。将热处理后的TNTs阵列置于1.5 mol/L的(NH4)2SO4电解液中进行电化学还原,制备了Ti3+掺杂的TNTs阵列。利用电化学阻抗谱研究了掺杂时间对纳米管阻抗的影响。X射线光电子能谱显示,在-1.45 V(相对于饱和甘汞电极)下经过60 s电化学还原自掺杂,可以使TNTs表面42.19%的Ti4+转化为Ti3+,从而有效降低了晶型转变后TNTs的阻抗。

A TiO2 nanotubes （TNTs） array was obtained on pure titanium substrate by anodic oxidation in 1.0wt% HF solution. The surface morphology and phase structure of the TNTs array were characterized by scanning electron microscopy and X-ray diffraction. The heat treatment at 450 ~C changes the TNTs from amorphous structure to anatase form. A Ti3＋-doped TNTs was prepared by electrochemical reduction of the heat-treated TNTs array in 1.5 mol/L （NH4）2SO4 electrolyte. The influence of self-doping time on conductivity of the TNTs was studied by electrochemical impedance spectroscopy. The results of X-ray photoelectron spectroscopy showed that nearly 42.9% Ti4＋ in TNTs was reduced to Ti3＋ after electrochemical self-doping at -1.45 V （vs. saturated calomel electrode） for 60 s, thus efficiently decreasing the impedance of TNTs after the formation of anatase phase.