铜铬双过渡金属共掺金红石相TiO_2的电子特性及引起的光谱红移效应

Electronic Properties and Spectrum Redshift Effect of Rutile TiO_2 Co-doped with Double Transition Metal Copper and Chromium

提高TiO2光催化活性已成为近年研究的热点。选取第一过渡金属Cu与Cr共同掺杂金红石相TiO2,运用基于密度泛函理论体系下的平面波超软赝势方法探讨了Cu-Cr共掺杂对金红石相TiO2电子特性和光学性质影响的微观机制。结果表明:Cu-Cr共掺杂TiO2在禁带中形成了5条新的杂质能级,其中价带顶的一条杂质能级主要是Cu3d轨道的贡献,而费米面附近的4条亚稳态杂质能级主要由Cr3d轨道和O2p轨道相互作用产生,有效减小了电子的跃迁能,改善了TiO2的光催化活性。Cu-Cr共掺杂也改善了TiO2的光学性质,使光谱红移,反射率增大,对可见光的吸收和反射能力比单掺杂更稳定。

Recently, it is becoming a research hotspot to improve photocatalytic activity of TiO2. The first row transition metal Cu and Cr are selected to be co-doped rutile TiO2. The effect micromechanism of electronic properties and optical properties of Cu-Cr co-doped rutile TiO2 are discussed by using the plane wave pseudopotential method based on the density functional theory. The results show that there are five new impurity levels formed in band gap of Cu-Cr co-doped TiO2. In which, one of impurity levels on valence band maximum is mainly contribution of 3d orbit of Cu, and another four metastable impurity levels are formed by interaction of 3d orbit of Cr and 2p orbit of O. Cu- Cr co- doped TiO2 is beneficial to decrease the transition energy of electron and largely improve photocatalytic activity of TiO2. The optical properties of Cu-Cr co-doped TiO2 is also improved, which has a red shift in visible region. And the reflectivity of TiO2 is increased. The visible light absorption ability and reflection ability of Cu-Cr co-doped TiO2 is more stable compared with these of Cu doped and Cr doped TiO2.