摘要:
采用第一性原理平面波超软赝势方法,系统研究了Mn,N共掺杂对锐钛矿相TiO2的晶体结构、缺陷形成能、电子结构、光学性质以及氧化还原能力的影响.研究表明：Mn,N共掺杂锐钛矿相TiO2后,TiO2晶格发生了畸变,导致晶体八面体偶极矩增加,有利于光生电子-空穴对的有效分离;在TiO2带隙中出现了杂质能级,使锐钛矿相TiO2的光学吸收带边红移,可见光区的吸收系数明显增大,有利于光催化效率的提高;在不考虑杂质能级的情况下,与纯TiO2相比,Mn,N共掺杂锐钛矿相TiO2带边的氧化还原势只有微小的变化.这些结果很好地解释了Mn,N共掺杂TiO2在可见光下具有优良的光催化性能的内在原因.
Abstract:
The effects of Mn and N codoping on the crystal structure,defect formation energy,electronic structure,optical property and redox ability of anatase TiO2 are investigated by first-principles calculations of plane-wave ultrasoft pseudopotential.The calculation results show that the octahedral dipole moment of anatase TiO2 increases due to its lattice distortion after Mn,N codoping,which is favorable for effective separation of photogenerated electron-hole pairs.Some impurity bands appear in the band gap,which leads to the red-shift of optical absorption edge and to the increase in coefficient of light absorption,thereby facilitating the enhancement of the photocatalytic efficiency.If the impurity band is not taken into account,the band edge redox potential of codoped TiO2 is only slightly changed compared with that of pure TiO2.All of these results can explain the better photocatalytic performances of Mn,N codoped anatase TiO2 under visible-light irradiation.
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