Thermodynamic stability of nitrogen functionalities and defects in graphene and graphene nanoribbons from first principles
Thermodynamic stability of nitrogen functionalities and defects in graphene and graphene nanoribbons from first principles
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DOI：
10.1016/j.carbon.2019.06.019
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发表时间：
2019-11-01
期刊：
影响因子：
10.9
通讯作者：
McEwen, Jean-Sabin
中科院分区：
文献类型：
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作者：
Ayiania, Michael;Hensley, Alyssa J. R.;McEwen, Jean-Sabin
石墨烯的氮官能化显著增强了石墨材料的物理和化学性质，增加了它们作为吸附剂、非均相催化剂和电子元件的适用性。能够通过处理条件选择性地诱导不同的氮官能度是设计和优化此类材料的关键。在这里，我们使用密度泛函理论来研究三种石墨烯结构中氮官能团的热力学稳定性，作为温度和压力的函数，为最有利的官能化配置提供原子学见解。相图表明，氮掺入是最放能在石墨烯边缘，与吡啶基团占主导地位的大多数条件下研究。对于所有氮官能团，较低的温度和较高的压力导致氮更多地结合到石墨烯结构中。态密度分析表明，稳定的吡啶氮结构诱导新的电子态，其能量是可调的，通过氮浓度，因此处理温度和压力低于费米能级。总的来说，我们已经表征了石墨烯和石墨烯纳米带内的氮官能团的热力学稳定性，允许通过实验对这种氮基团进行定向调节，并能够构建更现实的氮化石墨烯结构模型。(C)2019爱思唯尔有限公司版权所有。
Nitrogen functionalization of graphene significantly enhances the physical and chemical properties of graphitic materials, increasing their applicability as sorbents, heterogeneous catalysts, and electronic components. Being able to selectively induce different nitrogen functionalities via treatment conditions is key to the design and optimization of such materials. Here, we use density functional theory to study the thermodynamic stability of nitrogen functionalities in three graphene structures as a function of temperature and pressure, providing atomistic insight into the most favorable functionalized configurations. Phase diagrams show that nitrogen incorporation is most exergonic at graphene edges, with pyridinic groups dominating under the majority of conditions studied. For all nitrogen functionalities, lower temperatures and higher pressures result in the greater incorporation of nitrogen into the graphene structures. A density of states analysis shows that the stable pyridinic nitrogen structures induce new electronic states just below the Fermi level whose energy is tunable via nitrogen concentration and hence treatment temperature and pressure. Overall, we have characterized the thermodynamic stability of nitrogen functionalities within graphene and graphene nanoribbons, allowing for the directed tuning of such nitrogen groups experimentally and enabling the construction of more realistic models of nitrogenated graphene structures. (C) 2019 Elsevier Ltd. All rights reserved.