四价离子M（M=Mn,Pr,Sn,Zr,Se,Te）掺杂对CeO_2氧化还原性能的影响

于考虑了Ce-4f电子之间强关联作用PBE＋U方案,采用第一性原理计算方法系统研究了掺杂Mn,Pr,Sn,Zr,Se和Te等对CeO2原子结构、电子结构和还原性能影响.针对形氧空位后掺杂离子对体系中电子转移影响,提出了两种不同制：对于Zr,Se和Te等掺杂CeO2,氧空位形能的降低主要是受到氧空位形后结构扭曲影响;而对于Mn,Pr和Sn等掺杂体系,氧空位形能受到结构扭曲和电子转移双重影响,因此,氧空位形后电子首先转移到掺杂离子上而不是通常的Ce4＋上.研究发现,当四价掺杂离子到电子后最外层电子全满或半满结构时,氧空位形时所产生的电子会优先转移到掺杂离子上.

Effects of Mn, Pr, Sn, Zr, Se and Te doping on redox properties of CeO2

The effects of M （M=Mn, Pr, Sn, Zr, Se, Te） doping on the redox thermodynamics of CeO2 have been investigated using the first-principles density-functional theory considering the on-site Coulomb interaction within the PBE＋U scheme. Two different mechanisms for the O-vacancy formation in doped CeO2 have been clarified. Compared with the case of pure CeO2, the decrease in the O-vacancy formation energy for the Zr-, Se-, Te-doped CeO2 is mostly caused by the structural distortion, whereas the decrease for Mn-, Pr-, or Sn-doped CeO2 originates from the electronic modification as well as from the structural distortion. It is found that the electronic modification occurs in those dopants whose uttermost atomic orbitals are half or fully occupied by the filling of the excess electrons left by the formation of the O vacancy.