金属单原子模型催化剂热稳定性的反应力场(ReaxFF)分子动力学研究
Thermal Stability of Single Atom Metal Catalysts: ReaxFF Molecular Dynamics Study
作者单位E-mail
杨文琦 南开大学化学学院, 先进能源材料化学教育部重点实验室, 化学科学与工程协同创新中心(天津), 天津 300071  
汪杰 南开大学化学学院, 先进能源材料化学教育部重点实验室, 化学科学与工程协同创新中心(天津), 天津 300071  
乔园园 南开大学化学学院, 先进能源材料化学教育部重点实验室, 化学科学与工程协同创新中心(天津), 天津 300071 yuanyuanqiao@nankai.edu.cn 
王贵昌 南开大学化学学院, 先进能源材料化学教育部重点实验室, 化学科学与工程协同创新中心(天津), 天津 300071 wangguichang@nankai.edu.cn 
摘要: 金属催化剂的催化活性与其配位不饱和度密切相关,配位不饱和度越高,其催化活性一般也越高。单原子催化剂(SAC,或ad-atom)模型在金属表面上具有最小的配位数,因而往往表现为高的催化活性,但其热稳定性值得深入的研究。在本工作中,我们基于反应力场(ReaxFF),运用LAMMPS(large-scale atomic/molecular massively parallel simulator)软件包进行大尺度分子动力学模拟,研究单原子模型的热稳定性。模拟结果表明,只有Fe1/Fe(100)单原子催化模型可以在较高温度下稳定存在,而其他金属单原子表面分散结构则随温度升高而发生单原子聚集形成大的纳米颗粒或沉降的现象。同时我们也研究了在H2和O2气氛下Ni1/Ni(111)催化剂的动态行为,发现与真空环境相比,H2和O2气氛在一定程度上提高了催化剂的稳定性。
关键词: 金属单原子催化剂模型  热稳定性  反应力场(ReaxFF)  分子动力学  H2和O2气氛
基金项目: 国家自然科学基金(No.2173123)资助项目
Abstract: The catalytic activity of metal catalysts is closely related to its coordination unsaturation:The higher coordination unsaturation is, the better catalytic effect is in general. The single-atom catalyst (SAC or ad-atom) model has the smallest coordination number on metal surface and thus exhibits high catalytic activity, but the stability of SAC still need to be studied in detail. In this work, we used LAMMPS (large-scale atomic/molecular massively parallel simulator) for large-scale molecular dynamics simulation based on Reactive Force Field (ReaxFF) to study the thermal stability of the single atom model. The simulation results show that only Fe1/Fe(100) catalyst can be stable at high temperature (>500 K), while other SAC models will occur that single atom aggregates to form large nanoparticles or moves to subsurface as temperature increases. In the meanwhile, the dynamic behavior of Ni1/Ni(111) catalyst under H2 and O2 atmosphere was also studied was found that compared with simulation results in vacuum, the H2 and O2 atmosphere improved the stability of the catalyst to some extent.
Keywords: Single-atom catalyst model  Thermal stability  Reactive force field(ReaxFF)  Molecular dynamics  H2 and O2 atmosphere
投稿时间:2019-07-23 修订日期:2019-10-10
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杨文琦,汪杰,乔园园,王贵昌.金属单原子模型催化剂热稳定性的反应力场(ReaxFF)分子动力学研究[J].无机化学学报,2019,35(11):2078-2082.
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