Density Functional Theory Study Of Cerium Dioxide Modified By Heteroatom

Cerium dioxide catalyst has good oxygen storage and release capacity and has been widely used in many fields.The geometric structure,electronic structure and oxygen vacancy formation energy of metal-supported or doped CeO₂ catalysts were calculated by density functional theory,which can lay a theoretical foundation for the design of efficient catalysts.In this paper,the geometric structure,electronic structure and oxygen vacancy formation energy of Co modified CeO₂ catalyst were calculated by density functional theory.The Bridge site and Hollow site of Co loaded on the surface of CeO₂ catalyst and the surface of Co replaced Ce doped CeO₂ catalyst were investigated.The results show that Co doped CeO₂ catalyst can reduce the formation energy of oxygen vacancy on CeO₂ surface and increase the reactivity of oxygen on CeO₂ surface.The oxygen vacancy formation energy on CeO₂（110）surface can be reduced by Co loading in CeO₂（110）.When Co is loaded on the oxygen bridge site of CeO₂（100）,the formation energy of oxygen vacancy is negative,which is an exothermic process,which is more conducive to the oxygen defects on the surface of CeO₂（100）.For Co doped CeO₂（111）catalyst,the effect of M（3d,4d and 5d）doping on the oxygen vacancy formation energy near Co was investigated.It was found that the oxygen vacancy formation energy of MCo-CeO₂（111）was volcanically correlated with the number of electrons in the outermost d and s orbitals of the second metal,which provided a theoretical basis for screening the highly efficient MCo-CeO₂（111）catalyst.The geometric structure,electronic structure and oxygen vacancy formation energy of Cu and Ag modified CeO₂catalysts were calculated by density functional theory.The oxygen bridge site and vacancy of Cu or Ag on the surface of CeO₂ catalyst and the substitution of Ce doping on the surface of CeO₂ catalyst were investigated.The results show that Cu or Ag supported on the surface of CeO₂（100）catalyst is conducive to the formation of oxygen vacancy,and can improve the surface oxygen reactivity.In addition,for CeO₂（111）and CeO₂（110）crystal planes,Cu or Ag doping can lead to negative oxygen vacancy formation energy,which is an exothermic process,which is very conducive to the generation of oxygen defects on the catalyst surface.