Mixed-dimensional van der Waals heterojunction-enhanced Raman scattering

Van der Waals heterojunctions (vdWHs) provide an excellent material system for the research of heterojunction-enhanced Raman scattering (HERS) due to their complexity and diversity. However, the traditional two-dimensional vdWHs are not conducive to the full utilization of near-field light due to the limitation of single dimension. Herein, we fabricate T-shaped mixed-dimensional SnSe2/ReS2 vdWHs via chemical vapor deposition and wetting transfer method, and demonstrate that the mixed-dimensional vdWHs can be used as ultrasensitive HERS chips based on the effective photo-induced charge transfer. Besides, the radiative energy transfer effect enhanced by near-field light further magnifies the HERS signals, improving the detection limit of rhodamine 6G (R6G) to femtomolar level. Furthermore, we demonstrate that the ultrasensitive screening of crystal violet in multicomponent solutions adsorbed on SnSe2/ReS2 vdWHs can be achieved by adjusting the laser wavelength, which has not been achieved by noble metal materials. This work provides new insights into the mixed-dimensional vdWHs and demonstrates the great application potential of T-shaped heterojunctions.