N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, pr. ak. Lavrentyeva 9, Novosibirsk 630090, Russia.
Phys Chem Chem Phys. 2018 May 30;20(21):14740-14752. doi: 10.1039/c7cp08411k.
Graphene quantum dots (GQDs) are important for a variety of applications and designs, and the shapes of GQDs rely on the energy of their boundaries. Presently, many methods have been developed for the preparation of GQDs with the required boundaries, shapes and edge terminations. However, research on the properties of GQDs and their applications is limited due to the unavailability of these compounds in pure form. In the present computational study, the standard enthalpy of formation, the standard enthalpy of formation of edges and the standard enthalpy of hydrogenation are studied for hexagonal GQDs with purely zigzag and armchair edges in non-passivated and H-passivated forms using the semiempirical quantum chemistry method pm7. The standard enthalpy of formation of the edge is found to remain constant for GQDs studied in the range of 1 to 6 nm, and the enthalpies of edge C atoms are 32.4 and 35.5 kcal mol-1 for armchair and zigzag edges, respectively. In contrast to some literature data, the standard enthalpy of formation of hydrogenated edges is far from zero, and the values are 7.3 and 8.0 kcal mol-1 C for armchair and zigzag edges, respectively. The standard enthalpy of hydrogenation is found to be -10.2 and -9.72 eV nm-1 for the armchair and zigzag edges, respectively.
石墨烯量子点（GQDs）在各种应用和设计中都很重要，而 GQDs 的形状则依赖于它们边界的能量。目前，已经开发出许多方法来制备具有所需边界、形状和边缘终止的 GQDs。然而，由于这些化合物无法以纯态存在，因此对 GQDs 的性质及其应用的研究受到限制。在本计算研究中，使用半经验量子化学方法 pm7 研究了非钝化和 H 钝化形式下具有纯锯齿和扶手椅边缘的六边形 GQDs 的标准生成焓、边缘的标准生成焓和标准氢化焓。研究发现，在所研究的 1 至 6nm 范围内，GQDs 的边缘标准生成焓保持恒定，扶手椅和锯齿边缘的 C 原子边缘焓分别为 32.4 和 35.5kcal/mol。与一些文献数据相比，氢化边缘的标准生成焓远非零，分别为 7.3 和 8.0kcal/mol C。对于扶手椅和锯齿边缘，氢化的标准焓分别为-10.2 和-9.72eV/nm。
