In situ synthesis of large-area sixfold-oriented Mo₆Te₆ nanowires networks through hydrogen-assisted annealing of 2H MoTe₂ nanosheets

Phase transition and edge structure reconstruction of two-dimensional (2D) materials are critical for modulating their properties and applications. Here, we employ a hydrogen-assisted annealing method to accomplish the extensive transformation from a 2H MoTe₂ single crystal to Mo₆Te₆ nanowires and quasi-2D Mo₆Te₆ nanoribbons. Introducing hydrogen gas during atmospheric pressure annealing process generates a Te-poor chemical environment, which makes the transformations energetically favorable and is essential for the fast growth of Mo₆Te₆ nanowires. Mo₆Te₆ nanowires nucleate at the exposed edges of 2H MoTe₂ and grow along its [ $11\overline{2}0$], [ $\overline{2}110$], and [ $1\overline{2}10$] crystallographic directions, demonstrating long-range order and forming quais-2D nanoribbons with lengths up to 50 μm. Finally, nanoribbons align in sixfold oriented directions and form an array within 3 mm² area on SiO₂/Si substrate. Mo₆Te₆ nanowires display metallic behavior and have large charge transfer with Rhodamine 6G, making them excellent substrates for surface-enhanced Raman scattering. It shows a low detectable concentration of 10⁻¹³ mol/L for Rhodamine 6G and a Raman enhancement factor of 7 × 10⁸. Our findings provide an economic and efficient synthesis method for producing sixfold-oriented Mo₆Te₆ nanowires and nanoribbons networks, which can serve as platform for exploring low-dimensional physical properties, designing electronic devices, and applications in analytical chemistry.