Pt/Ce4O8团簇催化活性的第一性原理研究

基于密度泛函理论的第一性原理计算程序包VASP(Vienna ab-initio Simulation Package), 采用投影缀加平面波(Projector augmented wave, PAW)方法和具有三维周期性边界条件的超原胞模型, 对Pt在Ce4O8团簇上的吸附特性进行了研究. 结果表明Pt在Ce4O8团簇上的吸附作用很强，其吸附能大于Pt在CeO2晶体表面的吸附能. 所得吸附构型可分为三类：单键类, 双键类和多键类. 对其中最稳定吸附构型的电子结构分析表明：Pt的吸附诱导出了间隙态. 该态距离费米能级很近，使Pt/Ce4O8团簇活性很强. Pt与Ce4O8团簇发生了部分电荷转移, 从而使其中的一个Ce4+还原为Ce3+. 这些结果有助于理解在纳米尺度范围内Pt与CeO2的协同作用.

First-Principles Study on the Catalytic Activity of the Pt/Ce4O8 Nanocluster

The adsorption properties of Pt on the Ce4O8 nanocluster are studied using the first-principles projector-augmented-wave (PAW) method based on density functional theory (DFT) within local density approximation (LDA) and with the inclusion of on-site Coulomb interaction (DFT+U). The adsorption structures are classified into three types: the single-bond, the double-bond and the multi-bond structures. By a systematic analysis on the most stable configuration, it is found that: (1) there exists a strong interaction between the Pt atom and the Ce4O8 nanocluster with a lager adsorption energy than that on the CeO2 (111) surface; (2) The Pt atom loses electrons (0.42 e), resulting in the reduction of a Ce4+ to Ce3+; (3) A new gap state is induced in the gap between the O2p and Ce4f states, which is very close to the Fermi level and makes the Pt/Ce4O8 cluster more active. The results are helpful in understanding the synergistic effects of the Pt-CeO2 interaction at the nanoscale.