Bi2O3 /TiO2复合纳米颗粒的可见光光催化性能

采用溶胶与水热相结合的方法合成了具有可见光光催化活性的复合纳米颗粒Bi2O3/TiO2,并对其进行了X射线衍射、透射电镜、X射线光电子能谱、紫外-可见漫反射谱、红外光谱、低温N2吸附脱附及电子顺磁共振分析。结果表明,复合少量的氧化铋可显著抑制TiO2由锐钛矿到金红石的相转移过程,并将光吸收范围扩展到可见光区。可见光照射下(λ>420 nm),利用电子顺磁共振技术检测到明显的羟基自由基(.OH)信号。铋的最佳掺杂量为Bi/Ti质量比2.0%,适量铋的掺入能显著改善锐钛矿TiO2的结晶度,抑制光生电子-空穴对的复合,提高光催化量子效率。通过可见光照射下,4-氯酚的降解实验测试Bi2O3/TiO2复合纳米颗粒的可见光光催化活性。同时,利用气-质联用仪对4-氯酚降解过程的中间产物进行了测定,并提出可见光照射下的Bi2O3光敏化机理。

Visible Light Photocatalytic Performance of Bi2O3 /TiO2 Nanocomposite Particles

Visible-light photoactive Bi2O3/TiO2 catalysts were prepared by sol-hydrothermal process. The as-prepared samples were characterized by XRD, TEM, XPS, UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), FTIR,N2 adsorption-desorption and ESR. Compounding with low amounts of Bi2O3 could effectively inhibit the phase transformation from anatase to rutile. UV-Vis DRS showed an extension of light absorption into the visible region.ESR results indicated that the active species (·OH) was generated with visible illumination (λ＞420 nm). It was found that the optimal dosage of bismuth was 2.0wt%. Proper amount of bismuth species compounded on the TiO2 surface could improve the anatase crystallinity, which could inhibit the recombination between photoelectrons and holes, leading to enhanced photocatalytic quantum efficiency. Meanwhile, the enhanced visible-light activity was tested by the photocatalytic degradation of 4-chlorophenol (4-CP). Furthermore, the generated intermediates were identified using gas chromatograph-mass spectrometer and Bi2O3-photosensitization mechanism under visible light illumination was proposed.