德国德累斯顿工业大学的Xinliang Feng研究组取得一项新突破。他们合成了引入周期性锯齿状边缘段的凹边石墨烯纳米带。该项研究成果发表在2021年12月28日出版的《美国化学会杂志》上。

在此前研究的基础上，研究人员提出了一种具有周期性锯齿状短段的凹边石墨烯纳米带（GNR）。这种GNR家族的带隙可以通过锯齿形段的长度和沿相对边缘两个相邻凹单元的距离之间的相互作用来调节，可以从半导体转化为接近金属的带隙。通过由一种结构灵活的S型菲分子单体(1)在Yamamoto偶联后得到的一个独特的蛇形聚合物前体(10)之间的Scholl反应，研究人员合成了一种周期性锯齿状凸边纳米带的家族成员（N = 6 的zigzag-edged GNR,即6-CZGNR-(2,1)）。

通过FT-IR、Raman和UV-vis光谱以及对两种典型模型化合物(2和3)的研究，验证了聚合物10对6-CZGNR-(2,1)环脱氢反应的有效性。值得注意的是，合成的6-CZGNR-(2,1)在近红外区表现出扩展和宽吸收，在已有的溶液合成的GNR中，创下了有记录的窄带隙（0.99 eV）。此外，6-CZGNR-(2,1)具有较高的宏观载流子迁移率(~20 cm² V^-1 s^-1)，这主要是由于其本征有效质量小(m*e = m*h = 0.17 m0)，使其成为纳米电子学的候选材料。

据了解，结构精确的石墨烯纳米带由于其有趣且可调谐的电子结构而成为下一代纳米电子学的候选材料。具有混合边缘结构的GNR通常赋予它们独特的几何形状，与奇特的物理化学性质有关。

附：英文原文

Title: Cove-Edged Graphene Nanoribbons with Incorporation of Periodic Zigzag-Edge Segments

Author: Xu Wang, Ji Ma, Wenhao Zheng, Silvio Osella, Nicolás Arisnabarreta, Jrn Droste, Gianluca Serra, Oleksandr Ivasenko, Andrea Lucotti, David Beljonne, Mischa Bonn, Xiangyang Liu, Michael Ryan Hansen, Matteo Tommasini, Steven De Feyter, Junzhi Liu, Hai I. Wang, Xinliang Feng

Issue&Volume: December 28, 2021

Abstract: Structurally precision graphene nanoribbons (GNRs) are promising candidates for next-generation nanoelectronics due to their intriguing and tunable electronic structures. GNRs with hybrid edge structures often confer them unique geometries associated with exotic physicochemical properties. Herein, a novel type of cove-edged GNRs with periodic short zigzag-edge segments is demonstrated. The bandgap of this GNR family can be tuned using an interplay between the length of the zigzag segments and the distance of two adjacent cove units along the opposite edges, which can be converted from semiconducting to nearly metallic. A family member with periodic cove-zigzag edges based on N = 6 zigzag-edged GNR, namely 6-CZGNR-(2,1), is successfully synthesized in solution through the Scholl reaction of a unique snakelike polymer precursor (10) that is achieved by the Yamamoto coupling of a structurally flexible S-shaped phenanthrene-based monomer (1). The efficiency of cyclodehydrogenation of polymer 10 toward 6-CZGNR-(2,1) is validated by FT-IR, Raman, and UV–vis spectroscopies, as well as by the study of two representative model compounds (2 and 3). Remarkably, the resultant 6-CZGNR-(2,1) exhibits an extended and broad absorption in the near-infrared region with a record narrow optical bandgap of 0.99 eV among the reported solution-synthesized GNRs. Moreover, 6-CZGNR-(2,1) exhibits a high macroscopic carrier mobility of ～20 cm2 V–1 s–1 determined by terahertz spectroscopy, primarily due to the intrinsically small effective mass (m*e = m*h = 0.17 m0), rendering this GNR a promising candidate for nanoelectronics.

DOI: 10.1021/jacs.1c09000

Source: https://pubs.acs.org/doi/10.1021/jacs.1c09000