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.

低维材料的范德华 (vdW) 组装已证明能够创建具有按需特性的结构。据预测，vdW 封装可以引起几 GPa 的局部高压，这将强烈改变被捕获材料的结构和性能。在这里，我们报告了 vdW 封装引起的碳纳米管 (CNT) 的结构崩溃。通过简单地用六方氮化硼薄片覆盖碳纳米管，大多数碳纳米管（约77％）从管状结构转变为塌陷的扁平结构。无论其原始直径如何，所有塌陷的碳纳米管均表现出约 0.7 nm 的均匀高度，大致相当于双层石墨烯的厚度。拉曼光谱进一步证实了这种结构崩溃，拉曼 G 峰显示出显着的展宽和蓝移。局部 vdW 压力的分子动力学模拟完全捕获了 vdW 封装引起的 CNT 塌陷。进一步的近场光学表征揭示了伴随碳纳米管结构塌陷的金属-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，而且还为纳米电子应用提供了塌缩碳纳米管半导体。