Hu Cheng, Chen Jiajun, Zhou Xianliang, Xie Yufeng, Huang Xinyue, Wu Zhenghan, Ma Saiqun, Zhang Zhichun, Xu Kunqi, Wan Neng, Zhang Yueheng, Liang Qi, Shi Zhiwen
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
Collaborative Innovation Center of Advanced Microstructures, Nanjing, China.
Nat Commun. 2024 Apr 25;15(1):3486. doi: 10.1038/s41467-024-47903-3.
Van der Waals (vdW) assembly of low-dimensional materials has proven the capability of creating structures with on-demand properties. It is predicted that the vdW encapsulation can induce a local high-pressure of a few GPa, which will strongly modify the structure and property of trapped materials. Here, we report on the structural collapse of carbon nanotubes (CNTs) induced by the vdW encapsulation. By simply covering CNTs with a hexagonal boron nitride flake, most of the CNTs (≈77%) convert from a tubular structure to a collapsed flat structure. Regardless of their original diameters, all the collapsed CNTs exhibit a uniform height of ≈0.7 nm, which is roughly the thickness of bilayer graphene. Such structural collapse is further confirmed by Raman spectroscopy, which shows a prominent broadening and blue shift in the Raman G-peak. The vdW encapsulation-induced collapse of CNTs is fully captured by molecular dynamics simulations of the local vdW pressure. Further near-field optical characterization reveals a metal-semiconductor transition in accompany with the CNT structural collapse. Our study provides not only a convenient approach to generate local high-pressure for fundamental research, but also a collapsed-CNT semiconductor for nanoelectronic applications.
范德华（vdW）组装低维材料已被证明能够创建具有按需特性的结构。据预测，范德华封装可诱导产生高达几吉帕斯卡的局部高压，这将强烈改变被捕获材料的结构和性能。在此，我们报告了由范德华封装引起的碳纳米管（CNT）的结构坍塌。通过简单地用六方氮化硼薄片覆盖碳纳米管，大部分碳纳米管（约77%）从管状结构转变为坍塌的扁平结构。无论其原始直径如何，所有坍塌的碳纳米管都呈现出约0.7纳米的均匀高度，这大致是双层石墨烯的厚度。拉曼光谱进一步证实了这种结构坍塌，其显示出拉曼G峰有显著的展宽和蓝移。局部范德华压力的分子动力学模拟完全捕捉到了范德华封装引起的碳纳米管坍塌。进一步的近场光学表征揭示了伴随碳纳米管结构坍塌的金属 - 半导体转变。我们的研究不仅为基础研究提供了一种产生局部高压的便捷方法，还为纳米电子应用提供了一种坍塌碳纳米管半导体。
