Al掺杂CeO_2体系结构和电子性质的第一性原理研究

First-principles Studies on Electronic Structure and Chemical Properties of Al-doped Ceria

CeO_2因具有较高的储氧/释氧能力、较强的氧化-还原性能,受到人们极大关注,并在工业催化领域其有重要应用。杂质对CeO_2性能具有重要影响,用基于密度泛函理论的第一性原理方法和具有三维周期性边界条件的超晶胞模型,计算并分析了金属Al掺杂对CeO_2原子结构、电子结构和化学特性的影响。在计算中,用DFT+U方法描述Ce4f电子的强关联效应,用基于GGA的PAW势描述芯电子与价电子的相互作用。计算结果表明,Al掺杂降低还原能,使形成氧空位更容易,并从原子结构和电子结构等方面对掺杂降低还原能的机理进行了分析。

The geometric and electronic structures of the unreduced and reduced Al-doped ceria are systematically studied using the first principle method based on the density functional theory（DFT） within generalized gradient approximation（GGA） and with the inclusion of on-site Coulomb interaction（DFT＋U）. The projector-augmented wave method（PAW） is applied to treat the interaction of the core electrons with the valence electrons. It is shown that Al-doping substantially reduces the reduction energies, i. e. makes the reduction easier. The mechanisms that the Al dopant lowes the reduction energies are studied in detail from atomic and electronic structure analysis.