Confined Growth of Few-Nanometer MoS₂ Nanoribbons with Optical Anisotropy in Insulating Nanotubes

One-dimensional (1D) nanoribbons of transition metal dichalcogenides (TMDs) are predicted to exhibit exotic quantum phenomena that make them attractive for use in nanoscale electronic and spintronic devices. However, exploring the potential of ultranarrow TMD nanoribbons remains a challenge due to the lack of a suitable platform. Here, we report the atomically precise growth of ultranarrow MoS₂ nanoribbons within boron nitride nanotubes (BNNTs). The insulating nature of BNNTs enables direct optical probing of the encapsulated species without perturbing their intrinsic properties. Atomic-resolution transmission electron microscopy reveals the preferential growth of bilayers along the zigzag direction. Raman spectra confirm that the encapsulated structures experience significant strain. Angle-resolved polarized Raman spectroscopy reveals strong optical anisotropy in the 1D geometry, markedly distinct from that of the isotropic 2D MoS₂ sheets. Our approach offers an ideal platform for exploring intrinsic optical properties and device applications in ultranarrow TMD nanoribbons.