Abstract Pyrolysis dynamics of graphene oxide (GO) is critical for composite material design, and a few experimental evaluations were conducted so far since extremely high temperature condition is needed. In this work, with help of ReaxFF reactive molecular dynamics simulations, the pyrolysis mechanisms of GO were investigated from two aspects: (1) the structural evolutions of the carbon skeleton and (2) the desorption of the superficial functional groups. At low temperature, desorption of functional groups is dominant, and little point defects or vacancies are introduced to the carbon skeleton. Meanwhile, generation of a number of pyrolysis products was confirmed at higher temperatures. Accordingly, the carbon skeleton is significantly disordered, resulting in an amorphous transformation. Analysis of bonds breaking ratio, hybridization types of carbon atoms and pyrolytic fragments indicated that the restored sp2-hybridized carbons increase with the increasing annealing time, and structure of final products are controlled by hydroxyl and oxygen dangling bonds. Finally, annealing process of GO with different oxygenal group density (R) and OH/O ratio are quantitatively analyzed and found pyrolysis is R and OH/O ratio dependent. These results uncover the pivotal role of oxygen and hydrogen in pyrolysis, and provide a guidance for heat resistant composite designs.

中文翻译：

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ReaxFF分子动力学模拟揭示氧化石墨烯的热解机理

摘要 氧化石墨烯 (GO) 的热解动力学对于复合材料设计至关重要，由于需要极高的温度条件，因此迄今为止进行了一些实验评估。在这项工作中，借助 ReaxFF 反应分子动力学模拟，从两个方面研究了 GO 的热解机制：（1）碳骨架的结构演变和（2）表面官能团的解吸。在低温下，官能团的解吸占主导地位，碳骨架中引入的点缺陷或空位很少。同时，证实在较高温度下产生大量热解产物。因此，碳骨架显着无序，导致无定形转变。断键率分析，碳原子和热解碎片的杂化类型表明，随着退火时间的增加，恢复的 sp2 杂化碳增加，最终产物的结构受羟基和氧悬空键控制。最后，定量分析了具有不同氧基团密度 (R) 和 OH/O 比的 GO 的退火过程，发现热解依赖于 R 和 OH/O 比。这些结果揭示了氧和氢在热解中的关键作用，并为耐热复合材料设计提供了指导。定量分析了具有不同氧基团密度 (R) 和 OH/O 比的 GO 的退火过程，发现热解依赖于 R 和 OH/O 比。这些结果揭示了氧和氢在热解中的关键作用，并为耐热复合材料设计提供了指导。定量分析了具有不同氧基团密度 (R) 和 OH/O 比的 GO 的退火过程，发现热解依赖于 R 和 OH/O 比。这些结果揭示了氧和氢在热解中的关键作用，并为耐热复合材料设计提供了指导。