贵金属原子掺杂的CeO2（111）表面模型催化剂的理论研究

摘要

The geometric structures and electronic properties of MxCe1-xO2-δ(111) (M=Au, Pd, Pt or Rh) were systematically studied using density functional theory method. Results suggested that the structures of CeO2(111) surface change due to the doping of noble metal atoms. The surface oxygen vacancy formation energies of Au, Pd, Pt and Rh were 0. 32, 0. 41, 1. 04, and 1. 42 eV, which were much lower than that of the stoichiometric CeO2(111) surface. Therefore, the noble metals doped in ceria can promote the formation of oxygen vacancy, which significantly increased the catalytic activity. The density of state analysis results showed that the doping peaks appeared near the Fermi energy level. The charges of the doped atoms increased as the order of Au, Pd, Pd, and Pt, correspondingly. When forming oxygen vacancy, the charges of doping metal atoms were less than those of Mx Ce1-x O2 without oxygen vacancy.%通过DFT(密度泛函理论)的方法，详细的计算了不同贵金属原子，金( Au)、钯( Pd)、铂( Pt)与铑( Rh)在CeO2(111)表面掺杂模型催化剂的几何结构与电子性质情况。计算表明：掺杂贵金属原子将会使CeO2(111)几何构型发生不同程度的改变，将贵金属金、钯、铂与铑掺杂到二氧化铈中，形成模型催化剂。该类催化剂的氧空位形成能为0.32、0.41、1.04和1.42 eV比体相CeO2(111)表面的氧空位形成能大幅减小，有利于促进了氧空位的形成，掺杂体系的催化活性得到大幅提高。对态密度计算结果进行分析，在二氧化铈体相中掺杂贵金属原子，在费米能级处出现所掺杂的贵金属的电子锋，这充分说明，贵金属掺杂与CeO2(111)的相互作用明显大于贵金属吸附与CeO2(111)的相互作用。依照Au、 Pd、 Pt和Rh的次序，在CeO2(111)面掺杂金属原子失去电子的数目在明显的增多，在CeO2(111)面出现氧空位时，掺杂金属原子的电荷比相应化学计量模型电荷低。