金属Cd^(2+)掺杂TiO_2纳米颗粒的制备及能级结构的影响机理

Preparation of Cd^(2+) -doped TiO_2 nanopaticle and influence mechanism of their energy level structure

采用溶胶-凝胶法制备了Cd2+掺杂改性TiO2纳米颗粒,利用XRD、TEM、XPS和UV-Vis光谱对掺杂前后颗粒的结构和性能进行了表征。结果表明,溶胶-凝胶法制备的Cd2+掺杂TiO2纳米颗粒主要为锐钛矿相,粒径尺寸在20nm左右,掺杂前后TiO2的尺寸和形貌没有明显变化;结构表征和光谱测试结果发现,Cd元素在TiO2纳米颗粒中部分取代TiO2晶格中的Ti元素,以Cd2+的形式存在,形成Cd—O键,使TiO2纳米颗粒的吸收带边红移,降低了TiO2的禁带宽度。并且采用基于密度泛函理论的第一性原理对Cd掺杂TiO2进行了能级结构的模拟计算,发现理论结果与实验结果有较好一致性。

Cd^2＋ -doped TiO2 nanoparticles were prepared via sol-gel methods.These samples were characterized by X-ray diffraction（XRD）,transmission electron microscopy（TEM）,X-ray photoelectron spectroscopy（XPS）,and UV-Vis diffuse reflectance spectroscopy（DRS）.The results indicate that all the resultant undoped TiO2 nanoparticles consist of anatase crystallites with a size of 20nm,which the mothology and size were not significantly affected by doping at low doping concentration.XPS results showed that Cd replaced Ti in the crystal lattice and formed Cd-O bong,and absorption edge of TiO2 nanoparticles exhibit obvious red shift with a reduced band gap because of doping Cd^2＋.First-principles based on the density functional theory（DFT）was employed to investigate influence mechanism for the energy level structure of Cd^2＋ -doped anatase TiO2.The theoretical results are identical to the experimental results.