Synthesis of Rhombohedral WS₂/MoS₂ Nanoribbons with Enhanced Nonlinear Responses

One-dimensional (1D) transition-metal dichalcogenide (TMDC) nanoribbons are appealing for a plethora of emergent physics and innovative high-tech applications unattainable with their two-dimensional (2D) and bulk counterparts. Despite notable progress in synthesizing TMDC monolayer nanoribbons, the production of TMDC heterostructure nanoribbons, which can integrate the best characteristics of the constituent monolayers, remains elusive. Here, we realize the synthesis of rhombohedral, single-crystalline WS_2/MoS_2 nanoribbons through a multi-mechanism atomic manufacturing strategy combining vapour-solid-solid growth, vapour-liquid-solid growth, and self-etching. Over 90% of the as-produced rhombohedral WS_2/MoS_2 nanoribbons display an axial orientation parallel to the zigzag direction, evidencing excellent chiral homogeneity and controllability. Benefiting from the rhombohedral stacking order and 1D geometric structure, spatial inversion, out-of-plane mirror, and C_3 rotational symmetries are all broken, resulting in enhanced nonlinear optical responses and the emergence of a spontaneous photovoltaic effect. Our work establishes an effective and universal multi-mechanism route for implementing stacking-controlled TMDC nanoribbons, as well as other diverse 2D-material nanoribbons, potentially outlining a bright vision for a broad portfolio of emerging quantum, electronic, and optoelectronic devices.