采用电化学阳极氧化法, 在纯Ti表面一步制得原位生长的F掺杂TiO2纳米管阵列. 对煅烧后样品进行扫描电镜(SEM)、X射线多晶衍射(XRD)表征. 结果表明,所得TiO2纳米管排列整齐、平均管径约40nm, 平均管长约700nm. XPS蚀刻分析发现, 少量F原子以F-Ti-O键的形式掺杂进了TiO2晶格, 同时产生活性物质Ti3+. 可见光照射下,在0.25V(vsSCE.)外加阳极偏压下,673K煅烧后F-TiO2具有最高瞬态光电流密度(Iph)8.2μA/cm2, 这与光电极表面的Ti3+有关. 进一步的电子结构分析也表明,F掺杂未明显改变TiO2带宽.
Nanosized TiO2 has excellent photocatalytic activity to degrade most of pollutants.The most important focus has been on the improvement of photocatalytic activity and the efficiency of utilizing solar energy. The researches has proved that nonmetal-doping can activate its visible-light activity.Self-organized F-doped TiO2 nanotube arrays were fabricated by a one-step electrochemical anodization process on a Ti sheet. The prepared samples were annealed in air and detected by SEM, XRD and XPS. SEM images The results show that the well ordered TiO2 nanotube arrays with the average tube diameter of 40 nm and the average tube length of 700 nm are successfully fabricated. The substitutional F atoms that occupied oxygen sites in the TiO 2 crystal lattice cause the appearance of active spices Ti3+ , as evidenced by from XPS. The sample annealed at 673 K exhibits the highest photocurrent intensities under visible light irradiation, w hich may be attributed to the Ti3+ .The removal efficiency reaches 37.2% of AO7 at 180 min and the photoelectrocatalytic synergetic factor is 1.33. DFT study calculations suggests s that the valence and conduction band of F-TiO2 consist of the electrons of O2 p and Ti 3 d, while the small amount of electrons of F 2 p do not change the band gap of TiO2.
参考文献
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