Li Xingyu, Han Dong, Qin Tianchen, Xiong Juanjuan, Huang Jianmin, Wang Tao, Ding Honghe, Hu Jun, Xu Qian, Zhu Junfa
National Synchrotron Radiation Laboratory, Department of Chemical Physics and Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, University of Science and Technology of China, Hefei 230029, P.R. China.
Nanoscale. 2022 Apr 21;14(16):6239-6247. doi: 10.1039/d1nr08136e.
Kagome nanoporous graphenes (NPGs) are fascinating due to their exotic electronic and magnetic properties. The emerging on-surface synthesis (mostly on metal surfaces) provides a new opportunity to fabricate Kagome NPGs with atomic resolution. Previously the Kagome NPGs synthesized on surfaces were largely heteroatom-doped and suffer from morphological defects (evidently on metal surfaces). The on-surface synthesis of pristine Kagome NPG with improved structural quality is extremely desirable. In this paper, using a halogenated precursor, we report a bottom-up fabrication of pristine NPG with Kagome topology on Ag(111) classic Ullmann coupling. The templating effect of organometallic (OM) intermediates for subsequent covalent coupling is determined by comparing the OM phase and resultant covalent product. The reaction parameters are found to have a significant impact on the topology and quality of OM intermediates. Specifically, a higher surface temperature and lower evaporation rate favor the growth of better-quality and higher-yield OM Kagome NPGs. The covalent Kagome NPGs obtained by further annealing of these OM networks are affected likewise due to the template effect of OM intermediates. Our work further confirms the generality of the OM template effect. It also offers a novel method to achieve the selective synthesis of Kagome lattice networks.
戈薇型纳米多孔石墨烯（NPGs）因其奇异的电子和磁性特性而备受关注。新兴的表面合成方法（主要在金属表面）为以原子分辨率制备戈薇型NPGs提供了新机会。此前在表面合成的戈薇型NPGs大多是杂原子掺杂的，并且存在形态缺陷（在金属表面尤为明显）。因此，非常需要通过表面合成制备出结构质量更好的原始戈薇型NPG。在本文中，我们使用卤化前驱体，通过经典的乌尔曼偶联反应，在Ag(111)上自下而上地制备了具有戈薇拓扑结构的原始NPG。通过比较有机金属（OM）相和最终的共价产物，确定了有机金属中间体对后续共价偶联的模板效应。发现反应参数对OM中间体的拓扑结构和质量有显著影响。具体而言，较高的表面温度和较低的蒸发速率有利于生长质量更好、产率更高的OM戈薇型NPG。由于OM中间体的模板效应，通过对这些OM网络进一步退火得到的共价戈薇型NPG也受到同样的影响。我们的工作进一步证实了OM模板效应的普遍性。它还提供了一种实现戈薇晶格网络选择性合成的新方法。
