Cu掺杂TiO2纳米管可见光催化矿化甲苯

采用低温水热法制备氢钛酸管, 通过吸附-煅烧法制备Cu掺杂TiO₂纳米管(Cu-TNT)催化剂. 利用X射线衍射(XRD)、电感耦合等离子体-原子发射光谱(ICP-AES)、X射线光电子能谱(XPS)、透射电镜(TEM)、紫外-可见漫反射光谱(UV-Vis-DRS)和电化学测试手段对样品进行表征, 并进行平面波赝势密度泛函理论(DFT)计算. 结果表明, 样品中Cu/Ti原子比接近理论值, Cu掺杂进入TiO₂晶格内部, 诱发催化剂可见光活性. 掺Cu后,Cu 3d轨道和O 2p轨道杂化形成价带顶, 价带负向偏移, 样品禁带宽度减小为2.50-2.91 eV, 具有可见光响应.以甲苯为模型污染物研究催化剂对挥发性有机化合物(VOCs)的催化去除和矿化效果. 未掺杂的TNT可见光催化活性较差; Cu掺杂量超过0.1%(Cu/Ti原子比)时, 样品催化活性也减弱; Cu掺杂量为0.1%的催化剂具有最佳可见光催化氧化能力, 7 h内甲苯的去除率达77%, 甲苯的矿化率达59%.

Cu-Doped Titania Nanotubes for Visible-Light Photocatalytic Mineralization of Toluene

Based on hydrogen titanate nanotubes prepared by a low-temperature hydrothermal technique, Cu-doped titania nanotube (Cu-TNT) catalysts were prepared using absorption-calcination methods. They were characterized by X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectroscopy (ICP-AES), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis-DRS), and electrochemical techniques. Density functional theory (DFT) was used to calculate the nanotube band structure and density of states. Cu/Ti atomic ratios in the synthesized powders were very close to the nominal values, and the Cu-doped TiO₂ lattice exhibited improved visible-light absorption. This was because the valence band, formed by hybridization of O 2p states with Cu 3d states, was negatively shifted. Thus, the band gap was reduced to 2.50-2.91 eV and the samples exhibited visible-light responses. Toluene was chosen as a model pollutant to evaluate the removal capacity and the CO₂ mineralization rate of volatile organic compounds under visible light. Pure TNT displayed poor visible-light activity, and the activities of samples with >0.1% Cu doping were also weak. Samples doped with 0.1% Cu exhibited optimumvisible-light photocatalytic oxidation activity, with a 77%toluene degradation efficiency and a 59%mineralization rate in 7 h.