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采用分子动力学方法, 模拟了金属原子存在条件下缺陷石墨烯的自修复过程. 模拟采用了Ni和Pt两种金属原子作为催化剂, 通过改变系统温度, 得到了多组模拟结果. 观察对比了模拟结束时获得的原子构型图, 并通过计算修复过程中石墨烯内5, 6, 7元环的数量变化, 研究了不同金属原子对缺陷石墨烯的催化修复效果, 发现在适当的温度(1600 K和2000 K)下, 与无金属原子条件下的修复结果相比, 两种金属原子都表现出了一定的催化修复能力, 且Ni表现出的催化修复能力要优于Pt. 为了探究其背后的机理, 我们模拟了部分典型的结构演变. 发现Ni和Pt原子分别会导致“环内跳出”和“断环”的局部结构转变, 并且在不同温度下均表现出不同程度捕获碳链的能力. 此外, 观察了两种金属原子在平面内外的不同迁移行为, 并通过绘制金属原子的迁移路线, 计算其迁移量, 进一步研究了两种金属原子不同的催化修复机理. 研究结果有利于认识不同金属原子具有的不同催化修复效果, 理解不同金属原子的催化作用机制, 有助于针对缺陷石墨烯的修复选择合适的催化剂.Single-atom catalysts play a crucial role in repairing defective graphene, but the existing research on the single-atom catalysts focuses on the reduction of energy barriers. The unique repairing behavior of the single-atom catalysts in the graphene-healing process and the different repair mechanisms between different catalyst atoms have not been studied in depth. In this paper, the molecular dynamics simulation is used to study the the self-repairing process of defective graphene in the presence of Ni and Pt atoms. By changing the system temperature, multiple sets of simulations are obtained. By observing the atomistic structure obtained at the end of the simulations, the different catalytic repair effects are studied. We calculate the variation of 5, 6 and 7-member rings of graphene in the repair process, it is found that at the appropriate temperatures (1600 K and 2000 K), Ni atom shows stronger catalytic repair capability than Pt atom, and as the temperature increases, the repair effect on defects is also improved. By comparing with the repair process without metal atoms, we find that the effect of metal atoms is significant especially in repairing the carbon chain. To figure out the reason, some typical structure evolutions are simulated. The simulations show that when Ni atom can capture carbon chains at 1600 K, Pt atom needs higher temperature at least 2000 K. Apart from that, Ni and Pt atoms respectively lead to local structural transformations of " jump from the ring” and " bond breakage”. This may be the reason why the 5, 6, and 7-membered rings in the final structure of Pt catalytic system are less than those of Ni catalytic system at 1600 K and 2000 K. In addition, we map the migration route of metal atoms and calculate the migration distance. By observing the different migration behaviors of the two metal atoms in and out of the plane, the different catalytic mechanisms are further studied. The research results in this paper conduce to understanding the catalytic mechanism of metal atoms in the repair of defective graphene. It is of theoretical significance for selecting the external conditions and catalysts for the repairing of defective graphene.
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温度/K 1000 1600 2000 2500 催化剂类型 Ni 碳链 (5) 空缺 (1) 空缺 (0) 空缺 (0) 碳链 (1) Pt 碳链 (5) 空缺 (4) 空缺 (4) 空缺 (1) 碳链 (4) 
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