Mechanism of Graphene Formation via Detonation Synthesis: A DFTB Nanoreactor Approach
Mechanism of Graphene Formation via Detonation Synthesis: A DFTB Nanoreactor Approach
复制标题
通过爆炸合成形成石墨烯的机制：DFTB 纳米反应器方法
DOI：
10.1021/acs.jctc.9b00158
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发表时间：
2019-06-01
影响因子：
5.5
通讯作者：
Wen, Xiao-Dong
中科院分区：
文献类型：
--
作者：
Lei, Tingyu;Guo, Wenping;Wen, Xiao-Dong
随着理论和计算化学以及高性能计算的发展，分子模拟现在不仅可以用作解释实验结果的工具，还可以用作发现或预测的手段。量子化学纳米反应器是这样一种方法，它可以自动探索化学过程的基础上的基本力学没有先验知识的反应。本文提出了一种结合半经验量子力学密度泛函紧束缚（DFTB）方法和纳米反应器分子动力学（NMD）方法的新方法，模拟了不同氧/乙炔摩尔比下爆轰合成石墨烯的反应过程.石墨烯的形成是通过乙炔（C2 H2）分子通过碰撞断裂成诸如H原子、乙炔基（HC C中心点）和亚乙烯基（H2 C =CO自由基）的碎片而引发的。随后形成长直碳链与一些分支碳链，然后变成由碳环组成的二维框架。微量氧可以在石墨烯形成过程中调节环的大小，并促进具有稠合六元环的规则石墨烯的形成，如我们所见，但高氧含量的添加使得更多的含C物种氧化成小氧化物分子而不是聚合。与从头算纳米反应器相比，DFTB纳米反应器的计算速度大大提高，这使得它成为模拟大尺寸和长时间尺度的化学过程并帮助我们发现“未知的未知”的有价值的选择。
With the development of theoretical and computational chemistry, as well as high-performance computing, molecular simulation can now be used not only as a tool to explain the experimental results but also as a means for discovery or prediction. Quantum chemical nanoreactor is such a method which can automatically explore the chemical process based only on the basic mechanics without prior knowledge of the reactions. Here, we present a new method which combines the semiempirical quantum mechanical density functional tight-binding (DFTB) method with the nanoreactor molecular dynamic (NMD) method, and we simulated the reaction process of graphene synthesis via detonation at different oxygen/acetylene mole ratios. The formation of graphene is initiated by the breaking of acetylene (C2H2) molecules by collision into pieces such as H atoms, ethynyl (HC C center dot), and vinylidene (H2C=CO radicals. It is followed by the formation of long straight carbon chains coupled with a few branched carbon chains, which then turned into a 2-D framework made of carbon rings. Trace oxygen could modulate the size of the rings during graphene formation and promote the formation of regular graphene with fused six-membered rings as we see, but the addition of high oxygen content makes more C-containing species oxidized to small oxide molecules instead of polymerization. The calculation speed of the DFTB nanoreactor is greatly improved compared to the ab initio nanoreactor, which makes it a valuable option to simulate chemical processes of large sizes and long time scales and to help us uncover the "unknown unknowns".