水热处理锐钛矿TiO_2纳米管阵列及其增强的光电催化活性

Hydrothermal Treatment and Enhanced Photoelectrocatalytic Activity of Anatase TiO_2 Nanotube Arrays

在含氟溶液中,通过电化学阳极氧化钛片成功制备了高度有序的TiO2纳米管阵列,先在450℃下煅烧使其晶化为锐钛矿相,再在不同温度下水热处理了这些锐钛矿阵列。用XRD、SEM和XPS表征了所制备的样品。通过在氙灯光照下光电催化降解对氯苯酚水溶液来检测样品的活性。以对苯二甲酸作为探测分子,用荧光光谱检测了在氙灯光光照下样品表面产生的羟基自由基(.OH)。通过线性伏安扫描的间隙光照实验,测定了样品的光电流响应。结果表明后水热处理对锐钛矿TiO2纳米管阵列的结晶度和形貌没有影响,但光电催化活性明显增强,而不同温度处理的样品的活性差别不大。水热处理后的TiO2纳米管阵列的光电催化活性增强的原因是,水热后TiO2纳米管阵列表面羟基含量明显增加,使得其在光电催化过程中生成的.OH增加。

Highly ordered TiO2 nanotube arrays（TNs） were prepared by electrochemical anodization of titanium foil in a mixed electrolyte solution containing fluorions,and then calcined at 450 ℃ to transform them from amorphous to anatase,followed by hydrothermal treatment at different tempertures.The as-prepared samples were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）.The photoelectrocatalytic（PEC） activity of the samples was evaluated by degradation of p-chlorophenol aqueous solution under xenon lamp irradiation.The production of hydroxyl radicals（·OH） on the surface of xenon lamp irradiated samples was detected by a photoluminescence（PL） technique using terephthalic acid（TA） as a probe molecule.The transient photocurrent response is measured by several on-off cycles of intermittent irradiation.It was found that hydrothermal treatment exhibited no influence on the crystallization and morphology of anatase TNs,but the photocurrent density and PEC activity of anatase TNs after hydrothermal treatment were enhanced.There is little difference on the PEC activity ot samples after hydrothermal treatment at fifferent tempertures.The enhanced PEC activity of the anatase TNs was attributed to the fact that the increasing number of hydroxyl groups on the surface of anatase TNs after hydrothermal treatment,which enhanced the increasing of ·OH in the PEC process.