On the Thermal Stability of Aryl Groups Chemisorbed on Graphite
On the Thermal Stability of Aryl Groups Chemisorbed on Graphite
复制标题
石墨化学吸附芳基的热稳定性研究
DOI：
10.1021/acs.jpcc.9b09808
复制
发表时间：
2020
期刊：
影响因子：
--
通讯作者：
De Feyter Steven
中科院分区：
文献类型：
--
作者：
Gorp Hans Van;Walke Peter;Teyssandier Joan;Hirsch Brandon E. Uji-i Hiroshi;Tahara Kazukuni;Tobe Yoshito;Van der Auweraer Mark;De Feyter Steven
通过芳基重氮化学对碳基材料进行共价功能化已成为物理化学性质改性的有力工具。然而，传统上用于评估任何修饰的稳定性的表征技术，如热重分析(TGA)，不允许将共价脱离与物理吸附材料的损失区分开来。在这里，我们提出了一种将扫描探针显微镜和拉曼光谱相结合来区分这两个过程的一般方法。利用共价键修饰的高取向热解石墨(HOPG)，我们证明了通过这种组合方法可以直接监测芳基和HOPG表面之间的热致共价键断裂。此外，依赖于温度的拉曼光谱可以研究这种键断裂的动力学。因此，可以初步估计含有不同取代基的芳基的脱附活化能。最后，我们强调，可以在相对较低的温度下恢复原始的HOPG结构，为可逆的共价修饰开辟了道路。我们的结果提供了一种全面表征共价修饰碳材料的一般方法。
The covalent functionalization of carbon-based materials through aryldiazonium chemistry has emerged as a powerful tool for physicochemical property modification. However, the characterization techniques traditionally used to assess the stability of any modification, such as thermogravimetric analysis (TGA), do not allow covalent detachment to be discriminated from the loss of physisorbed material. Here, we present a general method to differentiate these two processes by combining scanning probe microscopy with Raman spectroscopy. Using covalently modified highly oriented pyrolytic graphite (HOPG), we show that the thermally induced covalent bond breaking between the aryl groups and the HOPG surface can be directly monitored through this combined approach. Moreover, temperature-dependent Raman spectroscopy allows the kinetics of this bond breaking to be studied. Desorption activation energies can thus be initially estimated for aryl groups bearing different substituents. Finally, we highlight that the pristine HOPG structure can be restored at a relatively low temperature, opening the way for reversible covalent modification. Our results alight on a general methodology for the full characterization of covalently modified carbon materials.