Oriented Epitaxial\nGrowth of Mixed-Dimensional van\nder Waals Heterostructures with One-Dimensional (1D) Bi<sub>2</sub>S<sub>3</sub> Nanowires and Two-Dimensional (2D) WS<sub>2</sub> Monolayers\nfor Performance-En

The synthesis of mixed-dimensional van der Waals heterostructures\nwith controlled alignment by chemical vapor deposition (CVD) technique\nremains a big challenge due to the complex epitaxial growth mechanism.\nHerein, we report the epitaxial growth of mixed-dimensional Bi<sub>2</sub>S<sub>3</sub>/WS<sub>2</sub> heterostructures by a two-step\nCVD method. Bi<sub>2</sub>S<sub>3</sub> crystals grown on 2D WS<sub>2</sub> monolayers exhibit 1D feature with the preferred orientation,\nindicating a strong epitaxial growth behavior at the 1D/2D interface.\nFurthermore, the heterostructure was carefully characterized by transmission\nelectron microscopy, which reveals the preferential growth of Bi<sub>2</sub>S<sub>3</sub> nanowires along the zigzag edge of WS<sub>2</sub> monolayers. The experimental results are also consistent with the\ntheoretical calculations by DFT, where the preferred orientation possesses\nminimal surface energy. The strong interaction between Bi<sub>2</sub>S<sub>3</sub> and WS<sub>2</sub> enables efficient charge transfer\nof photogenerated carriers at the heterointerface, which leads to\na largely improved light harvesting capability with the highest responsivity\nof ∼48.1 AW<sup>−1</sup> and detectivity of ∼5.9\n× 10<sup>12</sup> Jones.