Pt纳米颗粒几何特征与结构稳定性的原子尺度研究  

Atomistic study of geometric features and structural stability of Pt nanoparticles

作　　者：胡红远 邓磊[1] 陈方来[1] 魏小平[1] 戴震[1] 汤剑锋[1] 

机构地区：[1]湖南农业大学理学院,湖南长沙410128

出　　处：《湖南文理学院学报（自然科学版）》2014年第1期10-15,共6页Journal of Hunan University of Arts and Science(Science and Technology)

基　　金：湖南省大学生研究性学习和创新性实验计划项目(SCX1212);湖南农业大学引进人才科学基金项目(12YJ04)

摘　　要：基于金属纳米颗粒的几何特征及其幻数结构构建了一系列不同粒径和形貌的Pt纳米颗粒,利用改进分析型嵌入原子势与淬火分子动力学模拟研究了其结构稳定性.一方面揭示了各表面位比例、比表面积、平均配位数与粒径、形貌的定量关系;另一方面预测了晶体结构Pt纳米颗粒的平均原子结合能与颗粒尺寸的线性关联;二十面体形貌具有最密排的表面,尺寸较小时表面能的贡献使之成为首选结构,但大尺寸时应变能使之最不稳定;由于应变能的释放,晶态截切多面体小颗粒的稳定性与二十面体相仿,尺寸增大时具有最高稳定性.Based on the typical morphologies of metal nanoparticles（NP） and the magic numbers, a sierias of NPs were consturcted. The influence of particles’ sizes and morphologies on structural stability of Pt NPs have been investigated by using quench molecular dynamics simulations based on modified analytic embedded atom potentials. It is shown that average coordination number, surface-to-volume and site-to-surface ratio are all morphology- and size-dependent. Using energetic analyses as a guide, it is found that the average cohesive energy decreases linearly with the increasing particles’ sizes. As a result of the minimization of the strain energy and the surface energy, icosahedral NP is the most favorable morphology at small size but the least favorable one at large size. Better truncated decahedral or octahedral NPs are comparable with icosahedral at small sizes, and the most favorable at a range of particle sizes. These atomic-level understanding of the geometric features and structural stability of Pt NPs shed new light on the intelligently design of active and durable nanocatalysts.

关 键 词：纳米催化剂 几何特征 结构稳定性 分子动力学模拟 

分 类 号：O469[理学—凝聚态物理]