Studies of the Reactivity of Graphene Driven by Mechanical Distortions
Studies of the Reactivity of Graphene Driven by Mechanical Distortions
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DOI：
10.1021/acs.jpcc.2c05261
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发表时间：
2022-10
期刊：
影响因子：
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通讯作者：
Nathaniel Hawthorne;Sayanti Banerjee;Quentarius Moore;A. Rappe;J. Batteas
中科院分区：
文献类型：
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作者：
Nathaniel Hawthorne;Sayanti Banerjee;Quentarius Moore;A. Rappe;J. Batteas
在机械化学中，控制作用力的应用是改变反应速率和直接产物收率和选择性途径的关键。然而，在机械驱动反应的原子尺度上发生的事情与由此产生的宏观尺度结果之间存在着基本的知识差距。二维（2D）材料，如石墨烯，提供了一个模型系统来研究机械力（如应变）对化学反应性的影响，因为力分布可以应用于由单层C原子组成的组织良好的原子尺度结构。在这里，我们利用拉曼显微光谱和第一性原理计算，研究了石墨烯在不同应变程度下与4-硝基苯二氮鎓四氟硼酸盐（4-NBD）的反应。我们发现只有增加面外扭曲（将石墨烯的C原子从sp2电子态转移到sp3电子态）才能增加反应性，更大的面外扭曲产生更大的反应性。密度泛函理论（DFT）计算表明，石墨烯曲率的增加降低了4-NBD功能化的激活势垒，提高了反应的热力学有利性。此外，我们发现曲率会影响石墨烯2位轨道的取向，然后我们将4-NBD功能化的热力学可行性与轨道取向联系起来。这些研究指出了如何精确地应用力来指导石墨烯的官能化以进行C-C键形成反应，这对于以明确定义的方式控制其相应的电子结构具有重要意义。
In mechanochemistry, the application of controlled forces is key to altering reaction rates and pathways to direct product yields and selectivity. However, a fundamental knowledge gap exists between what is occurring on the atomic scale in mechanically driven reactions and the resulting macroscale outcomes. Two-dimensional (2D) materials, such as graphene, proffer a model system to study the impact of mechanical forces, such as strain, on chemical reactivity, as force distributions may be applied across a well-organized atomic-scale structure comprising a single layer of C atoms. Here, using Raman micro-spectroscopy and first-principles calculations, we have investigated the reaction of graphene, under varying degrees of strain, with 4-nitrobenzenediazonium tetrafluoroborate (4-NBD). We find that only with increased out-of-plane distortion (shifting the C atoms of graphene from sp2toward sp3electronic states) would the reactivity be increased, with larger out-of-plane distortions yielding greater reactivity. Density functional theory (DFT) calculations reveal that increasing the curvature of graphene decreases the activation barrier of 4-NBD functionalization and enhances the thermodynamic favorability of the reaction. Furthermore, we find that curvature affects the orientation of the graphene 2pzorbitals, and we then relate the thermodynamic feasibility of 4-NBD functionalization with the orbital orientation. These studies point to how the precise application of forces can be used to direct the functionalization of graphene for C–C bond forming reactions, which has significant implications for controlling its corresponding electronic structure in a well-defined fashion.