La掺杂Bi2O3的制备、表征与可见光催化活性

采用浸渍法制备了La掺杂Bi2O3(La-Bi2O3)光催化剂,利用X射线荧光光谱(XRF)、X射线衍射(XRD)、扫描电子显微镜(SEM)、傅立叶变换红外光谱(FT-IR)、X射线光电子能谱(XPS)、紫外-可见吸收光谱(UV-Vis)和光致发光谱(PL)等分析测试手段对样品的La掺杂量、晶体结构和光谱特征等进行了表征,并以2,4-二氯苯酚(2,4-DCP)水溶液的降解作为探针反应,考察了样品的可见光催化性能.结果表明,适量的La掺杂能有效抑制Bi2O3由四方相向单斜相转变,并将光吸收范围拓展到550 nm以上.掺杂的La可取代Bi2O3晶格中部分Bi,形成Bi—O—La键,并生成了少量镧铋复合氧化物(La0.176Bi0.824O1.5),它们的存在能有效抑制光生电子-空穴对的复合,从而提高光催化量子产率.可见光照射下2,4-DCP的光催化降解实验表明,La-Bi2O3具有良好的可见光催化性能,并且当La的掺杂量为3%(摩尔分数)时,催化剂的可见光催化效率最高.

Preparation, Structural Characterization and Visible-Light- Responsive Photocatalytic Performance of Lanthanum-doped Bismuth Oxide

Lanthanum doped Bi2O3(La-Bi2O3) photocatalysts were prepared by impregnation method.The doping quantity of lanthanum,crystalline phase structures and spectral properties of as-prepared photocata-lysts were characterized by X-ray fluorescence(XRF),X-ray powder diffraction(XRD),scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FT-IR),X-ray photoelectron spectroscopy(XPS),ultraviolet-visible spectrophotometry(UV-Vis) and photoluminescence spectroscopy(PL).The en-hanced visible-light activity was tested by the photocatalytic degradation of 2,4-dichlorophenol(2,4-DCP).Results of XRD show that appropriate amounts of lanthanum adulteration can effectively prevent the phase transformation of Bi2O3 from tetragonal to monoclinic.UV-Vis DRS results indicate an extension of light absorption into the visible region(higher than 550 nm).The doped lanthanum partially substitutes bismuth in the lattice of Bi2O3,which exists in the form of Bi—O—La chemical bond.And a new complex metal oxide compound(La0.176Bi0.824O1.5) appears in the catalysts,which could inhibit the recombination between photoelectrons and holes,leading to enhanced photocatalytic quantum efficiency.Furthermore,it is found that Bi2O3 doped with lanthanum of 3%(in mole ratio) has the superior photocatalytic performance for 2,4-DCP.