Symmetry-broken MoS2 nanotubes through sequential sulfurization of MoO2 nanowires

Transition metal dichalcogenide (TMD) nanotubes are emerging quantum materials with distinctive symmetry-breaking properties, offering significant potential for energy conversion technologies. However, the direct synthesis of crystalline MoS 2 nanotubes remains challenging due to limited understanding of their high-temperature growth mechanisms. Here, we present a robust and controllable strategy for the direct growth of crystalline MoS 2 nanotubes with well-defined tubular morphology and high structural uniformity. This approach features two key innovations: first, the controlled introduction of hydrogen reduces MoO 3 into one-dimensional (1D) tetragonal MoO 2 (space group I4/m) chains via a vapor–liquid–solid (VLS) mechanism; second, precise temperature zoning ensures timely sulfur vapor infusion for complete sulfurization. The intermediate MoO 2 phase, with its singular crystallographic orientation, acts as an ideal template for nanotube formation. Tellurium (Te) serves as a fluxing mediator to promote the formation of uniform MoO 2 nanowires, which are subsequently converted into MoS 2 nanotubes. By systematically tuning the hydrogen concentration, we reveal its critical role in directing product morphology. The resulting MoS 2 nanotubes exhibit pronounced symmetry breaking and significant bulk photovoltaic performance, achieving a photoresponsivity of 510 A cm −2 under 1.88 × 10 4  W cm −2 illumination. This work advances both the fundamental understanding of nanotube growth and the development of symmetry-engineered optoelectronic materials.