Developing efficient noble-metal-free surface-enhanced Raman scattering (SERS) substrates and unveiling the underlying mechanism is crucial for ultrasensitive molecular sensing. Herein, we report a facile synthesis of mixed-dimensional heterostructures via oxygen plasma treatments of two-dimensional (2D) materials. As a proof-of-concept, 1D/2D WO_3-x/WSe₂ heterostructures with good controllability and reproducibility are synthesized, in which 1D WO_3-x nanowire patterns are laterally arranged along the three-fold symmetric directions of 2D WSe₂. The WO_3-x/WSe₂ heterostructures exhibited high molecular sensitivity, with a limit of detection of 5 × 10⁻¹⁸M and an enhancement factor of 5.0 × 10¹¹ for methylene blue molecules, even in mixed solutions. We associate the ultrasensitive performance to the efficient charge transfer induced by the unique structures of 1D WO_3-x nanowires and the effective interlayer coupling of the heterostructures. We observed a charge transfer timescale of around 1.0 picosecond via ultrafast transient spectroscopy. Our work provides an alternative strategy for the synthesis of 1D nanostructures from 2D materials and offers insights on the role of ultrafast charge transfer mechanisms in plasmon-free SERS-based molecular sensing.

开发高效的不含贵金属的表面增强拉曼散射（SERS）基底并揭示其潜在机制对于超灵敏分子传感至关重要。在此，我们报告了通过二维（2D）材料的氧等离子体处理轻松合成混合维异质结构。作为概念验证，合成了具有良好可控性和再现性的1D/2D WO _{3- x} /WSe ₂异质结构，其中1D WO _3-x纳米线图案沿着2D WSe ₂的三重对称方向横向排列。 WO _3-x /WSe ₂异质结构表现出高分子灵敏度，即使在混合溶液中，亚甲基蓝分子的检测限为5 × 10 ^-18 M，增强因子为5.0 × 10 ¹¹ 。我们将超灵敏性能与 1D WO _3-x纳米线的独特结构和异质结构的有效层间耦合引起的有效电荷转移联系起来。我们通过超快瞬态光谱观察到约 1.0 皮秒的电荷转移时间尺度。我们的工作为从 2D 材料合成 1D 纳米结构提供了一种替代策略，并提供了关于超快电荷转移机制在无等离子体 SERS 分子传感中的作用的见解。