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Pt-Pd合金纳米粒子相对于Pt及Pd单晶纳米粒子均具有更好的催化活性和选择性,研究它的稳定结构对进一步了解催化性能具有重要意义.本文采用粒子群算法和量子修正Sutton-Chen多体势对不同尺寸、不同组成比例的二十四面体Pt-Pd合金纳米粒子的结构稳定性进行研究.结果表明:Pt-Pd合金纳米粒子中Pt原子趋向于分布在纳米粒子内层,而Pd原子趋向于分布在纳米粒子外层,且Pt,Pd原子的分布越对称有序,其能量越低,结构越稳定;随着Pt原子比例的增加,三种不同尺寸的合金纳米粒子的Warren-Cowley化学短程有序值都逐渐升高,即纳米粒子更趋向于偏聚分布状态;在相同比例下,小尺寸纳米粒子的偏聚程度比大尺寸纳米粒子的大.
Pt-Pd alloy nanoparticles have better catalytic activity and selectivity than Pt and Pd single crystal nanoparticles, and its stable structure is of great significance to further understand the catalytic performance.In this paper, particle swarm optimization and quantum correction Sutton- Chen Multi-body potential Stability analysis of tetragonal Pt-Pd alloy nanoparticles with different size and composition ratio The results show that the Pt atoms in Pt-Pd alloy nanoparticles tend to distribute in the inner layer of nanoparticles , While the Pd atoms tend to be distributed on the outer layer of nanoparticles, and the distribution of Pt and Pd atoms is symmetric and orderly. The lower the energy is, the more stable the structure. With the increase of Pt atomic ratio, three different sizes of alloy nanoparticles Warren-Cowley chemical short-range order values gradually increased, that is, the nano-particles tend to segregation distribution; in the same proportion, the small-size nano-particles segregation degree than the large size nanoparticles.