氮铋共掺杂TiO2的合成及其可见光催化性能研究

以纳米管钛酸为钛的前驱体,Bi(NO₃)₃·5H₂O为N源和Bi源,采用水热法制备了N、Bi共掺杂的TiO₂;并以甲基橙为目标降解物考察了所制备样品的可见光催化性能(λ≥420 nm).利用XRD、XPS、UV-Vis DRS、TEM等技术对不同条件下制备的产物进行了表征.结果表明,所得样品主要为锐钛矿型,粒径20 nm左右,掺杂的Bi主要以Bi₂O₃和BiONO₃两种形式存在.N元素除了以NO₃^-的形式存在于BiONO₃中,还有少量N以间隙氮掺杂于TiO₂中形成Ti-O-N键.N、Bi共掺杂的TiO₂在可见光下表现出了优越的光催化性能,其中水热温度为130 ℃,Bi/Ti摩尔比为1%时,催化活性最高.催化活性的提高源于N和Bi的掺杂增加了样品对可见光的利用效率,降低了光生电子空穴的复合速率.

Study on the Synthesis of N,Bi-codoped TiO_2 Nanoparticles and Their Visible Light Photocatalytic Performance

N, Bi-codoped TiO₂ samples were prepared by hydrothermal method using nanotubube titanic acid as the precursor of Ti and Bi(NO₃)₃·5H₂O as the bismuth and N source, respectively. The photodegradation of methyl orange (MO) was tested as a model pollutant to evaluate the photocatalytic activity of N, Bi-codoped TiO₂ under visible light irradiation (λ≥420 nm). The photocatalysts were characterized by X-Ray diffraction (XRD), transmission electron microscope (TEM), diffused reflectance spectra (DRS), X-ray photoelectron spectroscopy (XPS). The results indicated that the main phase of the samples was anatase, and the average grain size was 20 nm. The doped-Bi existed in the form of Bi₂O₃ and BiONO₃. As for the doped-N species, a part of N element existed in the form of NO₃^- of BiONO₃, and another existed in the interstitial position of the TiO₂ lattice to form the Ti-O-N bond in codoped samples. N, Bi-codoped TiO₂ exhibited remarkable photocatalytic activity under visible light irradiation. The codoped-TiO₂ prepared at 130 ℃(Bi/Ti=1%,molar ratio) showed the highest photocatalytic activity. The enhanced photocatalytic activity of N, Bi-codoped TiO₂ was more likely ascribed to the fact that doped-N and Bi increased the utilization efficiency of visible light, and while decreased the recombination rates of photogenerated electrons and holes.